Assessment of Mercurity Toxicity Hazard Associated with Former Cinnabar Mining and Tailings Disposal in Honda Bay, Palawan T M Williamd, J M Weeks, A Apostol, C Miranda British Geological Survey WC/96/31/R

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BRITISH GEOLOGICAL SURVEY
TECHNICAL REPORT WC/96/31/R
Overseas Geology Series
Assessmentof mercury toxicity hazardassociated
with formercinnabar miningand tailings disposal
in Honda Bay, Palawan,Philippines.
T M Williams', J M Weeks2, A Aposto13 & C. Miranda'
1:British Geological Survey, Keyworth,Nottingham, UK.
2: Institute of TerrestrialEcology,Monks Wood Station, Cambs. UK.
3: Mines and GeosciencesBureau, Diliman, Quezon City,Philippines
A report prepared for the OverseasDevelopment AdministrationEngineering
Division under ODA-BGScontractR6226:Mitigationof mining-related
mercury pollution hazards.
ODA classification
Subsector:Geoscience
Theme: Identify and ameliorateminerals-relatedgeochemicaltoxic hazards.
Project title:Mitigation of mining-related mercury pollution hazards.
Project Reference:R6226.
Bibliographic reference: T M Williams, J M Weeks, A Apostol and C
Miranda 1996:Assessmentof mercury toxicity hazard associatedwith former
cinnabarmining and tailings disposal in HondaBay, Palawan, Philippines. British
Geological Survey,Overseas Geology SeriesTechnical Report WC/96/31,
Keyworth, Nottingham, UK.
Key words: Mercury, mining, tailings disposal, human health, toxicology.
Cover illustration: Former Palawan Quicksilver Mining Inc. operation,
Santa Lourdes, near Puerto Princesa,Palawan,

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SYNOPSIS
An assessment of mercury (Hg) contamination and attendant human exposure associated with former
cinnabar mining activities on the Philippine island of Palawan was undertaken by the British Geological
Survey (BGS) in collaborationwith the UK Institute of TerrestrialEcology (ITE) and the PhilippinesMines
and Geosciences Bureau (MGB) in December 1995. The study followed a formal request from the
Philippines Department of Environment and Natural Resources (DENR) for assistance in investigating
media reports of human mercury poisoning near the former Palawan Quicksilver Mining Inc. (PQMI)
operation at Santa Lourdes. Funding for the work was provided by the UK Overseas Development
Administration(ODA) under TechnologyDevelopmentand Research (TDR) programme R6226: Mitigation
of Mining-Related Mercury Pollution Hazards.
The aims of the study were (i) to establishthe spatial extent and magnitude of Hg contamination within the
marine environment of Honda Bay, eastern Palawan, (ii) to evaluate temporal trends of Hg deposition in
marine sedimentswith particularreferenceto any flux adjustmentsassociatedwith the onset of mining, (iii)
to assess the risk posed to local populations as a consequenceof living on or near a mine-waste substrate,
(iv) to assess the extent of Hg bioassimilationand attendanttoxicological stress in marine biota, and (v) to
assess alternative(nonmining-related)sources of Hg exposureincludingpotable water.
Marine sedimentcores were used to assess spatial and temporal trends of Hg deposition in Honda Bay. The
averageHg concentration in surficialsediment at offshore sampling stations throughout the study area was
found to be c. 40pgkg, and is thus within the global backgroundrange. Downcore Hg profiles indicate no
significant adjustment of Hg influx over the past c. 100years.
Geochemical and mineralogical analyses of mine waste from the Sitio Honda Bay jetty structure were
undertaken to establish the total concentration and bioavailability of Hg. Profiles through the waste
characteristically display a depthward reduction of Hg concentration, from surficial values of up to 340
mgkg to basal concentrations of <40 mg/kg. The solid-phasespeciation of Hg in the <2mm fraction of the
waste is dominatedby inorganic non-sulphideHg-phases (generally constituting~90%of the total Hg mass
balance), These phases are of typically low bioavailability. Human Hg exposure through particulate
inhalation or hand-mouth ingestionis thereforeconsideredunlikely to be significant.
Analyses of aquifer- and stream water samples from the study area provided no evidence of Hg
contamination, with values typically below 40 ng/l. The role of potable water as a source of human Hg
exposure is thus likely to be negligible.
Mercury concentrationsin six speciesof fish from Honda Bay were found to fall within the ranges typically
encounteredfor analogousspecies worldwide.Median Hg values for all analysed species lie within the US-
EPA marketingthreshold of 0.5 mgkg. Mercury burden data for the shellfish P e w Viridis (green mussel)
highlightedsignificanttissue Hg enhancement (to 21 mg/kg dry weight) in samples collected from within
10-20m of the Sitio Honda Bay jetty. Concentrations in samples collected from a coral island c. 7 km
offshore were found to fall within the global background range (c3 mgkg dry weight). Attendant
toxicologicalstress in the Sitio HondaBay sampleshas been inferredfrom neutral-red biomarker assays.
Human Hg body burdens were appraisedfor 130Palawan subjectsthrough the collectionand analysisof hair
samples.The results indicate that all Palawan residents are subject to high Hg exposure,relative to a control
population from Manila. It is, however, unlikely that this is reflective of geological or mining influences.
Statisticalanalysis of data for five Palawan sub-groupsfailed to significantlydiscriminate those living on a
mine-waste substrate from and other populations. Estimated mean blood Hg values for the five sample
groups ranged from 8.8 - 17.6 ng/ml, with a maximum individual value of 74.1 ng/ml. Such values am
typical of populations consuming fish at a daily frequency. There i s virtually no evidence of appreciable
toxicologicalrisk at blood concentrationsof this magnitude.
The data presented in thisstudy do not substantiatethe claims made in the Philippine media during August
and September 1995 regarding the occurrence of a major mercury poisoning episode in Palawan. The
conclusions of this study are, however, based largely on a single field sampling programme. Longer-term
monitoring is recommended to gain a more comprehensive understanding of the sources, environmental
behaviour and toxicity of Hg on the island of Palawan and elsewhere.
1

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1: INTRODUCTION
Research into the environmental and human impacts of mercury (Hg) contamination in the
Philippines was initiated by the BGS in April 1995 as a component of an Overseas
Development Administration (ODA) Technology Development and Research (TDR)
programme R6226: Mitigation of Mining-Related Mercury Pollution Hazards. The
fundamental aims of the programme are (i) to design and test a protocol for monitoring the
spatialextent and magnitude of mining-related Hg contamination, (ii) to assess the human
and toxicological significance of such contamination and (iii) to examine the potential for
modifying mineral-processingtechnologiesto reduce environmentalHg fluxes.
At the project outset, Eastern Mindanao was jointly identified by staff of the BGS and the
Philippines Mines and GeosciencesBureau (MGB) as an appropriate focus for research due
to the extensive gold-rush which has occurred in the region during the last two decades,
with widespread utilisation of Hg for gold amalgamation. In August 1995, the MGB were,
however, forced to reappraise their priorities in the light of widespread media reports of
human mercury poisoning in an area of former cinnabar mining on the island of Palawan.
In response to a directive from Philippines President Fidel Ramos, the MGB commissioned
an inter-agency investigationinto the Palawan scare, and a formal request for the diversion
of BGS-ODA funds from Mindanao to Palawan was received by BGS in September 1995.
Although falling strictly beyond the remit of TDR project R6226 (which is primarily
concerned with Hg pollution associated with artisanal gold mining), the request was
consideredby BGS and ODA to constitute a strong case for demand-led TDR expenditure,
Accordingly, a preliminary BGS-MGB investigation of the extent of the Palawan Hg
problem was sanctioned in December 1995, and executed with assistance from the UK
Institute of Terrestrial Ecology (ITE).This report outlines the results of this survey and
their implicationsfor future policy development within the area of concern.
2: STUDY AREA:
The area of reported human Hg risk on the island of Palawan encompasses three barangays
(villages), Santa Lourdes, Sitio Honda Bay (SHB) and Tagburos (Fig. l), situated
approximately 14km north of Puerto Princesa (lat. 118"42'E, long. 09"JO'N). The area is
drained by the Tagburos River, which flows in a south-easterly direction into Honda Bay.
The coastal margin is characterised by low lying topography (e50 m),with an extensive
marsh area occupying the lower 1 km of the Tagburos River floodplain. The coastal
environment of Honda Bay is dominated by primary mangrove vegetation.
2

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Palawan, and the immediateprovision of centralgovernment funds to support one or more
of the following actions:- (i) detoxification of approximately 25%of the local population
(based on the 25%failure of subjects in the preliminary DOH survey to meet the ‘normal’
blood threshold of 20 ng/ml), (ii) provision of a laboratory facility at Puerto Princesa
Provincial Hospital for the analysis of Hg in blood, (iii) removal of the Sitio Honda Bay
jetty and safe disposal of the contaminated tailings, (iv) resettlement of the c. 200
population of Sitio Honda Bay, (v) dredging of sediments from contaminated sectors of
Honda Bay.
3.3: Areas of uncertainty:
By late 1995, the widespread publicity surrounding the Palawan mercury scare had
imposed a significant economic impact on the island, notably its fishing industry as a
consequence of concern over product quality amongst wholesale purchasers in Manila.
Prior to the BGS/ITE survey, however, little quantitative data existed to show the genuine
extent of ecotoxicological risk to populations living close to the PQMI mine, on the Sitio
Honda Bay jetty, or those consuming fish from Honda Bay. Particular uncertainty may
have arisen through the misrepresentationof the geochemical data of Benoit et al (1994) in
the media which, in failing to emphasise the extremely localised nature of the study,
inferred that anomalous Hg concentrations were characteristic of the entire Honda Bay
floor. In reality, the gradients reported by Benoit et al(1994) show concentrations declining
rapidly from 560mgkg on thejetty, to 38 mgkg at 25 m distance,and 2.3-18.8mgkg at a
distance of 200 m. Data for control sites 7-10 km offshore indicate the prevalence of
conditionswithin the global background range (0.03 -0.2mgkg).
Uncertainties in the preliminary biological and ecotoxicological datasets collated by the
EMl3 and DOH primarily reflect the small sample populations involved. For example, the
occurrence of ‘Minamata range’ Hg concentrations in fish and shellfish from Honda Bay
reported by the EMB (and subsequentlyby the Philippine media) was based on the analysis
of only 6 samples, collected in November 1994. Follow-up sampling of a further 6 fish
samplesby the EMB in May 1995 yielded Hg values at least an order of magnitude lower
than those reported in 1994. While seasonal factors were invoked to account for this
discrepancy, the inherent variability of trace metal concentrations in biological samples
could have been equally influential.
The conclusionsdrawn from the DOH human blood survey of 42 subjects from the Honda
Bay area could also be considered equivocal. Of the 12 subjects who yielded blood Hg
values exceeding the 20 ng/d threshold, 50% were former miners or roasting plant
operators. Data for these individuals do not therefore infer any wider exposure of the
8

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population via the food chain. Within this sub-group the highest recorded value (25 ng/ml)
can be regarded as low for individuals subject to long-term occupational exposure.
Although clinical symptoms of Hg poisoning have been observed in a limited number of
Honda Bay miners, it is unlikely that these could have been caused by blood Hg levels of
this magnitude. Reference data from a comprehensive UNEPNHO-endorsed Monitoring
and Assessment Research Centre (MARC) study indicate that the lifetime exposure
threshold required to induce symptoms of clinical Hg poisoning is 80 ng/ml, with effects
typically absent at levels of c200 ng/ml. Clinical damage in miners could, however, have
been caused by short-term exposure (no longer reflected in blood) up to several
decadespreviously.
4: AIMS OF BGS-MGB-ITE STUDY
In view of the paucity of geochemical, ecotoxicological or epidemiological data depicting
the extent or magnitude of Hg hazards in centraleastern Palawan, the central aims of the
BGSATE study were:-
1: Establishmentof the spatialextent and magnitudeof Hg contamination within the
sediments of Honda Bay
2:Evaluationof temporal trends of Hg deposition in the marine environment, with
particularreference to flux adjustments associated with the onset of mining and the
construction of the SitioHonda Bayjetty.
3: Assessment of the risk posed to populations of Sitio Honda Bay jetty and the
PQMI mine locality as a consequence of living on a mine-waste substrate (and
hence the need to re-house such populations).
4:Assessment of the extent of Hg bioassimilation and attendant toxicological stress
in marine biota (fish and shellfish) at various localitiesin Honda Bay, and appraisal
of the significanceof SitioHonda Bay as a contaminant sourcefor biota.
5: Assessment of alternativepotential sources of Hg exposure (eg. potable water)
6: Preparation of recommendationsfor remedial action, if appropriate.
5: METHODOLOGY AND RESULTS
3.1: Marine sediment study.
5.1.1: Sample selection: A survey incorporating 12 offshore gravity coring stations and
numerous additional coastal auger sites in HondaBay (Fig. 7) was undertaken by the MGB
research vessel Explorer in September 1995. Cores of up to 4 m length were split
lengthwise on return to the MGB laboratory in Manila, and sub-sampled to yield
contiguous 10cm stratigraphic sections. Analysis of total Hg in all core and auger samples
9

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CORE NO
2
7
9
25
served to provide both a more detailed record of Hg fluxes to Honda Bay during the past
century, and also an independentcorroborationof existingMGB analyticaldata through the
re-analysis of duplicatematerials at BGS, Keyworth.
LOCALITY
P.PrincesaBay
S.of Canon
Island
Bacungan
River
Central H. Bay
Of the coring stationsincluded in the BGS study, sites 7 and 9 were selected on account of
their proximity to Sitio Honda Bay and the Tagburos estuary (ie. the major postulated
sourcesof Hg contamination). Site 25, located c. 20 km offshoreat a water depth of 43 m,
was selectedto provide an indication of bay-wide impacts. Site 2 was selected as a control
site, as this Puerto Princesa Bay station receives sediment from unexploited cinnabar
deposits located in the upper Inawayan catchment (Fig. 7). Lithological information for
each core is given in Table 1.
LAT / LONG W.DEPTH
09'44.26N 23 m
Table 1: Core descriptions for BGS sampling stations in Honda Bay.
CORE LGH
4 m
118'42.89E I I
09'48.02N I 3 5 m I 0.4m
118'48.16E
09'53.47N
118'46.11E
09'52.06N 43 m
118'55.71E
LOG. DESC.
Homogeneousolive grel
silty clay.
0-24cm: olive-grey
silty clay with forams.
25-44cm:dark olive-
brown clay.
Dark grey clay with
forams. Sulphidic.
0-10cm: silty clay with
forams. 11-45cm: olive
grey silty clay with
forams. 48-69cm: olive
grey clay. 70-400:grey-
5.1.2: Analyticalprocedures: A total of 56 core sub-samples of c. 4 g mass analysed for
total and inorganic Hg analysis. All sub-samples were air-dried at low temperature
(<40°C), disaggregatedand ground to a fine powder using a milling procedure designed to
minimise heat generation. An appropriate mass of sample(c. 1g) was weighed into a 5Oml
graduated test-tube and digested with cold aqua-regia under air-reflux for 24 hours. The
tubes were then sealed (to avoid loss of volatile Hg) and heated to 140°Cfor two hours,
cooled and diluted to volume.
All sediment sample digests were analysed by cold-vapour atomic fluorescence
spectrophotometry (CVAFS), using an SP-Analytical Insts. Merlin AFS system. A
conventional method of cold vapour generation was utilised, involving the reduction of
Hg2+to Hgowith stannouschloride, and argon streamtransportation of the Hg vapour into
the AFS detector. The practical detection limit for Hg (in solution) by this method is 10
ngll.
1 1

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Data for two mangrove mud samples from the mouth of the Tagburos River show a Hg
concentrationof 8 mgkg (PW 9 & 10). This value is substantially higher than recorded n
offshoresediment,reflecting an ultrafine (clay-dominated)granulometry and high capacity
for Hg adsorption.
The proportion of the total Hg load carried in -150 pm sediments and heavy mineral
concentrates (HMC) varies significantlybetween the Tagburos River stations (PW4 & 5)
and the gulley incised into the PQMI tailings pile (station PW 1). In the former, the
concentrationof Hg in the HMC is greaterthan that in the sedimentby a factor of c. 2.5-7.
In the latter,the HMC yields a lower Hg value than the sediment, suggesting that much of
the Hg in the waste-pile is either ultra-fine cinnabar, or has been weathered from detrital
sulphides and repartitioned into secondary phases. Downstream of the confluence, in the
mid-reaches of the Tagburos River, this fine Hg-rich load does not significantly enrich the
bottom sediment (e.g. at station PW5), but remains largely in suspension under the flow
conditions prevailing. The deposition of this load in the very low energy environment of
the estuarinemangroves is, however, likely, to contribute to the 8 mgkg Hg concentration
recorded in this area.
Qualitativefield observationsof the flow regime of the Tagburos river suggest that the total
sediment discharge (and hence the total Hg flux) from this system into Honda Bay is
unlikely to be substantial. Compared to the larger Bacungan system to the north, the
Tagburosriver is small, sluggish and carries a bankful discharge of no more than 50 m3/S.
The lower reaches (within 0.5 km of the coast) are also characterisedby extensive marshy
areas and mangroves, which act as an effectivefilterfor suspended sediment.
5.3: Sitio Honda Bay mineralopicalassessment.
5.3.1: Methodology: Previous chemical analyses of superficial waste from Sitio Honda
Bay have indicated the presence of an average Hg concentrationof 560 mgkg (Benoit et
al., 1994).Such values have prompted speculation that the structure may be unsuitable for
habitation, and re-settlementhas been proposed for the c. 200 residents. To fully evaluate
the risk, quantitative data regarding residential Hg exposure (including dust or vapour
inhalation, hand-mouth ingestion or consumption of contaminated garden produce) are
required for this population, with any additionalexposurerelating to occupationalor dietary
factors carefully differentiated.
Geochemical and mineralogical data indicating the concentration, speciation and
bioavailability of Hg in mine tailingscan providea directinsightinto the likely toxicological
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Sizefraction
>SO0 um
constituting c. 30% of total sample mass). Weight-percentage data for the tail and HMC
components in each of the sub-500 pm fractions indicate that the HMC is only a
small component of the solid assemblage (max. 7% total mass) throughout the analysed
Wt. of tail Wt of HMC
37.81 1.037
size range.
Hg in tail
280
Table 3: Concentration of mercury (mg/kg) in Sitio Honda Bay waste.
Hg in HMC % balance in tail
210 98
PW21 A I Mangrovemud to SW of jetty I 57
PW21 B I As above. I 48
320
210
The proportion of the Hg mass-balance held within heavy minerals was found to be
generally small (~20%)in all analysed samples, indicating that cinnabar is of lesser
importance than secondary alteration products as a carrier of Hg in the waste. Data for
station PW6, however, suggest that the precise significance of the HMC varies
significantly with both depth and grain size. In the surficial sample PW6- A, the coarse
>SO0 and >250 pm fractions were found to hold ~ 4 %of total Hg in heavy minerals,
rising to over 35% in the <20 pm fraction. Cinnabar within the waste must, therefore, be
predominantlyfine-grained and prone to rapid weathering.
220 96
310 79
Table 4: Grain-size and gravimetric partitioning of Hg in Sitio Honda Bay
waste sample PW6A. All weight data are in grams. All concentration data are in
mgkg. HMC = heavy mineral concentrate.
>63 pm
>20 pm
<20 pm
EvaDorate
10.01 1.708
15.81 1.708
35.42 -
3.919 -
>250 um I 14.92 10.985
>120um 1 12.37 11.798
270 1_U "ll410 1360
800
e20 -
1 9

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>500 pm
>250 pm
>120 um
Table 5: Grain-size and gravimetric partitioning of Hg in Sitio Honda Bay
waste sample PW6B. All weight data are in grams. All concentration data are in
mgkg. HMC =heavy mineral concentrate.
29.32 0.998 80 60 98
14.57 0.697 80 80 96
9.724 0.581 80 90 94
>63 pm
>20 pm
c20 pm
EvaDorate
5.405 0.426 80 30 97
23.02 0.625 150 80 99
15.33 - 310 - -
1.201 - <20 - -
% balance in tailWt. of tail
28.57
9.417
Size fraction
>500 pm
>250 pm
>120 pm
>63 pm
>20 pm
c20 um
~
990.567
1.195 120 140 85
768.543 1.570
1.716
2.699 330 260
8.952
9019.76
I I
8.652
Evaporate i 2.458
Table 6: Grain-size and gravimetric partitioning of Hg in Sitio Honda Bay
waste sample PW6C. All weight data are in grams. All concentration data are in
mgkg. HMC = heavy mineral concentrate.
% balance in tail
99
96
94
94
97
Evaporate I 1.300 I- I <20 I -
Table 7: Grain-size and gravimetric partitioning of Hg in Sitio Honda Bay
waste sample PW6D. All weight data are in grams. All concentration data are in
mgkg. HMC =heavy mineral concentrate.
Sizefraction Iwt. of tail
I
Wt of HMC IHg in tail IHg in HMC I % balance in tail
I I
2 0

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The datasets for more deeply buried samples, PW6-C and D show the HMC contribution to
the Hg mass-balanceto remain below 6% across the entire grain-size range. Any cinnabar
originally present in waste forming these horizons must, therefore, have been
comprehensivelydegraded and the Hg repartitionedinto clays. The prevalence of maximum
Hg concentrationsof up to 550 mg/kg in the <20 pm (tail) componentsof PW6 B, C and D
is consistent with this hypothesis.
Microprobe analysis of the <20 pm fraction of sample PW6 A was undertaken to establish
the composition of secondary Hg compounds in the Sitio Honda Bay waste.This confirmed
that the Hg in the clay-dominated assemblage is primarily held as an inorganic impurity in
(or sorbedto) hydrous Fe oxide phases such as goethite and ferrihydrite.
In a previous study of Sitio Honda Bay waste and nearshore sediment geochemistry,
Benoit et al. (1994) noted a decline in the proportion of total sediment Hg held in sulphide
with increasing distance from Sitio Honda Bay, and proposed syn-dispersal dissolution
and conversionto more labile (bioavailable)forms as a plausible cause. From the evidence
now available regarding the presence of substantial concentrations of non-sulphide Hg
within thejetty waste, these seaward adjustments to the Hg totaVHgS ratio could possibly
be reinterpretedas a function of gravimetric sorting of cinnabar and secondary Hg carriers
in the fine-silt and clay size range following the erosion of waste from the jetty by wave
action. The role of methylation processes in the regulation the ratio can be specifically
discounted, as both the Sitio Honda Bay waste and the marine sediments of Honda Bay
hold Hg almost exclusively in inorganic phases.
5.4: Hvdrochemical survev;
5.4.1: Background: The potential for human Hg exposure through consumption of
contaminated water in the Santa Lourdes area has received considerable attention, but
existing datasetsyield no consistent trend. The MGB have previously collected two suites
of samples.Each included water from the PQMI open pit, samples from shallow tube wells
immediately south of the PQMI site and surface water from Tagburos River. The first suite,
analysed at the MGB Quezon City laboratory, yielded no values in excessof 0.2 pg/l. The
second suite was submitted to SGS (Philippines) Inc. who reported concentrationsan order
of magnitude higher, mostly in the range 2-4 pg/l.This discrepancymay reflect the fact that
both sample suites were unfiltered, and thus probably held variable suspended loads. In
addition, the analysisof waters by CVAAS in both laboratories may have resulted in poor
precision through operationclose to the limit of detection.
2 1

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5.4.2: Sampling and analytical methods: Water samples were collected from four surface
water localities, five boreholes and one thermal spring for full hydrochemical
characterisation,total Hg and inorganic Hg analysis. Surface water sampling stations (see
Fig. 9) included Tagburos River sites upstream and downstream of the PQMI mine, the
PQMI open-pit and drainage water from the adjacent tailings pile. Boreholes, ranging in
depth from 12- 45 m, were primarily located in SantaLourdes (proper),along the southern
flank of the PQMI site (Fig. 9).
At each station, three 30 ml samples were filtered through a 0.45 pm Millipore cellulose
acetate membrane into Sterilin storage tubes. One was then stabilised with 0.6 ml
50%HN0,+50%K2Cr0, for total and inorganic Hg analysis, a second was acidified with
0.3 mlconcentrated HNO, (Aristar) for major/trace cation analysis (by ICP-AES), and the
third was retained unacidified for anion analysis (by ion chromatography). Field
measurementsof pH, Eh, conductivity and temperature were taken during sampling, using
a series of Orion and Hanna Instruments meters and appropriatecalibration standards.
Water samples for Hg analyis were split into equal aliquots for the independent
determinationof total and inorganic Hg. Total Hg analyses were conducted following pre-
treatmentof one aliquot with a brominatingagent to oxidise all organo-mercury compounds
to inorganic species. The differencebetween the Hg value recorded for this sub-sample and
that for the corresponding non-brominated aliquot was assumed to constitute organo-Hg.
For both aliquots, the oxidant preservative (K,CrO,) was reduced using a dilute solution of
NH,.OH.HCl immediately prior to analysis. All determinations were made by CVAFS
using the methodology described in section 5.1.2.
5.4.3: Results: Data showing the concentration of total Hg, plus all other hydrochemical
parameters determined in the surface- and groundwater sample suite,are shown in Table 8.
Mercury was in all instances found to be present as >99% inorganic species, and
accordinglyorgano-Hg data have not been presented. In all surface waters (PQMI mine pit
and Tagburos River samples), Hg was present at concentrations below the CVAFS
detection limit of 20 ng/l (O.ooOo2mg/l). In the SantaLourdes groundwater suite one value
exceeding the 20 ng/l detection limit was recorded (40 ng/l at station PW 19), but can be
considered to fall within the global backgroundrange. A Hg concentration of 140 ng/l was
recorded in sulphidic spring water at station PW 15.
The basic hydrochemical signatures of all surface- and groundwater samples are
summarisedin Fig. 14, in which major cation, anion and TDS data are plotted on a Piper
2 2

26. e
e
a
a
e
e
a
0
e
a
a
a
a
e
e
a
a
0
e
a
a
e
e
0
0
a
e
0
a
a
e
0
PW18-G 0.012 0.02 2.995 0.05 24.1
PW19-G 0.002 0.03 0.640 0.01 31.7
PW20-G 0.001 0.10 0.025 0.05 21.7
Table 8: Multi-element data for surface- and groundwater samples from the
Santa Lourdes area. Suffixes indicate sample type: S = surface water; G =
groundwater; H = hot spring .All element concentration data are given in
mg/l. ND = NOT DETECTED.
ND 0.15 ND ND 0.02
ND 0.02 0.03 ND
ND 0.52 ND 0.01
Sample
PW2-s
PW3-s
PW4-s
PW5-s
PWlS-H
PW16-G
PW17-G
PW18-G
PW19-G
PW20-G
Hg pH
<0.00002 4.57
<0.00002 7.96
0.00014
<0.00002
<0.00002
6.02I
<0.00002 I 6.54
Eh (mV) Temp (C) Cond (US)
510 33 190
490 31 786
480 28 363
450 29 311
-295 80 6200
300 28 114
310 28 581
-50 31 506
260 30 664
310 31 794
Sample I H C 0 3 I C1 I SO4 1 NO3 I TOC I TIC I Mg
p w 2 - s I <20 10.62 121.2 I ~ 0 . 116.48 I 0.69 12.18
PW3-S I72 142.4 1245.0 I 1.11 I 13.3 I 13.6 158.6
P W ~ - s 233 4.9 4.41 ~ 0 . 17.84 44.2 28.9
PWS-s 188 6.4 24.9 0.38 12.5 36.8 27.6
PW15-H 2570 779.0 5.11 42.0 10.8 489.0 15.4I
PW16-G 35 14.1 545.0 ~ 1 . 010.5 I 7.63 93.7
PW17-G 210 37.4 29.9 CO.1 8.72 I 39.5 28.5
76.8 I 19.1 I 4.44
4 .4 4.8 1. 9
2 4

27. 5.5: Marine fish survev:
5.5.1: Background: Following the preliminary DOH assessment of human blood Hg
burdens in the Santa Lourdes-Tagburos area in 1995 (section 3.2), it was proposed that
contamination by mining activities of Honda Bay fish stocks may account for the
prevalenceof elevatedHg levels in a small number of individuals who had neither worked
at the PQMI mine, nor resided on or near any known mine-waste accumulation. This
hypothesis was further strengthenedby the preliminary conclusions placed on Hg data for
fish and shellfish sampled by the EMB in November 1994 (see sections 3.2 and 3.3),
showing drv weipht concentrations to range from c.005 mgkg for dalagang-bukid, to
10.96mgkg for the predatory species,lapu lapu. For shellfish, dry weight concentrations
for Perna viridis (mussel) were reported as 2.1 mgkg, while oyster concentrations of 36.9
mgkg were recorded. When compared uncorrected against the wet weight values for fish
and shellfish at Minamata (0.4 -30.0 mgkg and 1.3- 14.0 mgkg respectively), the Honda
Bay concentrations appear high. However, when expressed on a wet weight basis, the
values for all species sampled appear more moderate:- 1.78 mgkg for bisugo, <0.005
mgkg for dalagangbukid, 0.142 mgkg for galunggong, 2.00 mgkg for lapu lapu, 0.560
mgkg for matang baka and 0.684 mgkg for salay salay. A repeat survey of a similar
speciesrange in April 1995 yielded considerably lower Hg values, ranging from <0.0005
mgkg for danggit and salay salay to a maximum of 0.076 mgkg for lapu lapu (wet
weight). It is notable that both EMB surveys were based on a single analysis for each
species. Considerable inherent variability of Hg burden is likely to occur between
individualsof all species studied, and this may provide the most plausible explanation for
the contasting results obtained. In both surveys, the values presented for most elevated
species are analogous to those reported as ‘normal’for long-lived predatory fish worldwide
(see Piotrowski and Inskip, 1981,for a comprehensivesummary).
A subsequentstudy of fish Hg burdens in Honda Bay was conducted in 1995by a research
team from the University of the Philippines. Two sample suites were collected in
independent trawls, and representative numbers of 9 species (with widely varying
ecologies)analysed. The results showed only two speciesto carry mean burdens in excess
of the US-EPA marketing threshold of 0.5 mgkg Hg. Highest concentrations (mean
0.924 mgkg) were found to prevail in a predatory species (talakitok), for which such
values could be considerednormal (Piotrowskiand Inskip, 1981).
5.5.2:Methodology: In the present study, 6 species of fish were collected with nets from
both the inner and outer Honda Bay areas. The fish types taken are known only by local
name: malakapas, salmonete,tuko, taba-taba, sap-sap and mackerel (confirmation of genus
and species is awaited from the University of the Philippines). On the basis of morphology
2 5

28. 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
e
0
0
0
0
0
0
0
0
these species appear to reflect a broad spectrum of feeding guilds and trophic levels. Thus
the fish groups sampled would record potential Hg exposure through the full range of
detrital,algal and carnivorousfood chain pathways.
Muscle samples from ten individuals of each species were dried at 50°C within 6 hr of
collection (to facilitate transport to the UK without substantial decomposition) and the
weight loss assessed in each case. All samples were subsequently digested in HNO,,
diluted to an appropriatevolume and analysed for Hg by CVAFS using the instrumentation
described in section 5.1.2.
5.5.3: Results: Full analytical data (expressed as both dry weight and approximate wet
weight) and summary statistics depicting the Hg burden of all fish samples are given in
Table 9. The mean wet weight values reported for all species (0.09 - 0.33) are broadly
consistent with those previously produced by University of the Philippines researchers.
For the single species studied in both surveys (sap sap), the comparative wet weight mean
values are 0.27 (UPI) and 0.31 (BGSBTE). Statistical analysis (ANOVA followed by
Tukey HSD multiplecomparisons) of the data on an inter-species basis indicates that sap-
sap and mackerel have significantlyelevatedHg concentrationsrelative to all other species.
With respect to the mackerel,this distinctionis entirely consistent with the high position of
these species in the food chain. There is no statistically significant differentiationbetween
than the remaining groups.
Table 9 (a-f) : Mercury burdens in Honda Bay fish (mg/kg).
2 6

29. 0
0
0
0
0
e
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Table 9 (cont.)
I I I
RANGE IMalakapas 10.05 - 0.42 10.25 - 2.10 I
0
0
0
0
0
0
2 7

30. 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Taba Taba
Taba Taba
Taba Taba
Taba Taba
Table 9 (cont.)
0.05 0.24
0.07 0.32
0.09 0.45
0.05 - 0.32 0.22 - 1.64
Sample no.
12.01
12.02
12.03
12.04
12.05
12.06
12.07
12.08
12.10
MEAN VALUE
RANGE
2 8

31. 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Other
non-
Dredatorv
Table 9 (cont.)
Sample no.
14.01
14.02
14.03
14.04
14.05
14.06
14.07
14.08
14.09
14.10
MEAN VALUE
RANGE
0.08 - 0.27 0.07 - 0.09 0.02 - 0.16 0.10 - 0.30 0.09 - 0.19
Mackerel
Dry weight Hg
3.21
1.31
1.19
1.32
2.41
0.90
1.87
1.41
2.53
1.70
0.87 - 3.21
Comparison of the wet weight Hg burdens in Honda Bay fish with threshold values for
marketed fish in the USA (0.5mgkg, US-EPA), and with global average data for species
of varying ecologies (e.g. IRPTC, 1980; Table 10) indicates that the mean and, more
significantly, the median levels prevailing in the Honda Bay samples are not exceptional.
Separationand subsequent statisticalanalysisof data for individual specimenscaught in the
inner and outer sectors of HondaBay yielded no significantdifferentiation.Realistically,all
sampled species are extremely motile, hence significant differences across a continuous
area of open water could not be expected.
Table 10: Approximate average wet-weight mercury levels (mg/kg) in
muscle tissues of marine fish in major oceans worldwide.
2 9

32. e
a
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0
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a
0
0
a
0
0
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0
0
0
0
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0
a
0
0
0
0
0
c
0
0
0
0
0
0
5.6: Mussel (Permviridis) assessment
5.6.1: Mussel Hg assays: Bivalves are excellent indicators of heavy metal contamination,
due to both their capacity to accumulate metals from their environment (mainly in particulate
form), and their widespread distribution throughout the world. In many regions, bivalves
also form an important source of human nutrition, and may therefore constitute a significant
pathway for human metal exposure. On account of the biomagnification of metals which
typically occurs during assimilation by shellfish, any small increase in ambient metal
concentrationresulting from pollution will typically be reflected by a distinct increase in
mussel tissue concentrations.
During the BGS/ITE Honda Bay survey, samples of the species P e m viridis (green
mussel) were collected from two locations. The first was situated in shallow water
approximately 10m off the southernmargin of the Sitio Honda Bay jetty (near site PW 6,
Fig. 13). The second was located close to the western shore of Canon island,
approximately 6 km off the Tagburos - Sitio Honda Bay coast (see Fig. 7). All samples
were returned to the haematology laboratory of Puerto Princesa Hospital for preparation
and biomarker assessment within 8 hours of collection. All samples were purged in clean
water prior to sub-sampling.
The soft tissues of 15 mussels from Sitio Honda Bay (coded PW6) and 10 from Canon
Island (coded PW13) were air-dried at 50°C prior to transport to the UK for final weight
determination and analysis. The dry tissues were partially digested in cold HNO, at ITE
(Monks Wood) and forwarded to BGS for furtherreflux digestion and total Hg analysis by
CVAFS.
5.6.2: Results: Dry weight and approximate wet weight Hg data for all mussel samples
from Sitio Honda Bay and Canon Island are given in Table 11. The average wet weight
value (2.13 mg/kg) and range (0.86 - 4.37 mgkg) established for the Sitio Honda Bay
suite is almost an order of magnitude greater than that for Canon Island (mean 0.34
mgkg). The Sitio Honda Bay mean value falls within the lower quartile of the Minamata
shellfish range (1.3 - 14.0 mgkg), indicating that mussels and analogous filter feeders
from the immiediate vicinity of the jetty may be unfit for human consumption. The
contaminationof biota in this locality is entirely accordant with the high Hg concentrations
observed in sedimentfrom the same vicinity (seeBenoit et al., 1994; or MGB survey data,
September, 1995), and lateral concentration gradients for the two media are probably
analogous. Accordingly, it is plausible that bivalve Hg tissue burdens decline to
background within a few hundred metres of the Sitio Honda Bay source. The & Hg
concentrations recorded in P e m viridis from the Canon Island station is within the
3 0

33. a
0
0
0
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0
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a
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e
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0
0
0
0
0
e
0
0
0
0
0
0
Sample
PW13-1
PW13-2
PW13-3
PW13-4
PW13-5
internationalbackground range for shellfish, signifyingthat bivalves from the wider Honda
Bay may be suitable for human consumption.
Wet wt Dry wt Hg Sample Wet wt Hg Dy wt Hg
Hg
0.45 2.28 PW13-6 0.24 1.22
0.29 1.45 PW13-7 0.36 1.84
0.24 1.24 PW13-8 0.27 1.36
0.58 2.92 PW13-9 0.41 2.08
0.26 1.30 PW3-10 0.31 1.57
Table ll(a): Dry weight and approximate wet weight mercury
concentrations (mg/kg) in tissues from Honda Bay mussel samples (Perna
viridis).
Table ll(b): Mercury concentrations (mgkg) in Honda Bay mussel samples
(cont).
5.6.3: Neutral-red biomrker assessment. An ecotoxicological field test based on the
neutral-red retention (NRR) capacity of invertebrate cells has been successfully utilised to
assess metal-induced stressin a number of marine and terrestrial settings (e.g. Weeks and
Williams, 1995).In the present study, haemolymph (0.02-0.05 ml) was extracted from 25
mussel specimens from sites PW6 and PW13, and mixed with an equal volume of
temperature-adjusted physiological ringer using a 1 ml hypodermic syringe. Each
haemolymph suspension was transferred then to a siliconized Eppendorf (0.5 ml) for
subsequent (NRR) analysis,
3 1

34. a
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0
A neutral-red stock solution, comprising 20 mg of neutral-red dye dissolved in 1 ml of
dimethyl sulphoxide,was freshly prepared. Subsequently, 10 pl of the stock solution was
diluted with 2.5 ml of physiological ringer, giving a working concentration of 80 pg/ml.
To avoid crystallization of the neutral-red dye, the working solution was renewed every
hour during the measurement process. Haemolymph samples of 20 ~1were placed on a
microscope slide,and the cells allowed to adhere to the slide surface for 3 minutes before
the application of the neutral-red working solution (20pl) and a cover-slip.
Each slide was continuously scanned at random (by rapid haphazardous repositioning)
under a microscope (at constant magnification) to observe any temporal adjustments to the
condition of the cells. Each visualization was divided into 3 minute intervals, from which
the numbers of cells with fully stained and unstained cytosol were determined. Observation
was stopped at the interval when the ratio of stainedunstained cytosol was greater than
50% of the total number of cells counted. The midpoint of the interval was noted as the
NRR time.
5.6.4:Results: A statistically significant difference (P<O.OOl) was observed (based on a
Student’st-test two sampleanalysis, assuming unequal variances) between the NRR times
determined for mussels from the SitioHonda Bay and Canon Island locations. The former
had an averageNRR-time of 15min (+3.0), while latter consistently displayed at retention
of e. 45 min (f4.0). These trends are consistent with an increased level of toxicological
stress and attendant cell dysfunction in the Sitio Honda Bay sample population. While
alternative causes of stress (eg. between-site temperature, salinity or organic pollutant
variations)have not been specificallydiscounted,the close correlation between NRR times
and Hg tissue burdens at the two sample sites is most likely to be causal.
5.7: Assessment of human HPburdens:
5.7.1:Background The extent to which the populations of Santa Lourdes and Sitio Honda
Bay are exposed to Hg through residence on, or near, a mine waste substrate can be
inferredfrombioavailabilitydata derived from mineralogicalstudies of Hg speciation in the
waste material (section 5.3). Such studies, must, however, be supplemented by direct
monitoring of the potentially impacted populations (alongside one or more appropriate
control groups) to produce a comprehensive risk assessment. Hair analysis is
internationally recognised as suitable for this purpose (e.g. WHO, 1981). The method
holds advantagesover blood Hg analysis as it is non-invasive, and results are not prone to
short-term dietary influences. Hair Hg burdens are a direct function of average blood
3 2

35. e
0
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0
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0
0
a
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a
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a
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a
0
0
0
@
0
e
0
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0
0
0
0
concentration (section 5.7.4 below) and can thus be used to make crehble inferences
regardingblood burdens.
5.7.2: Methodology: An electoral list was acquired of individuals living in three selected
samplingareas:- (i) Sitio Honda Bay (a community living on a mine-waste substrate), (ii)
Santa Lourdes proper (a community living at the margin of the PQMI site) and (iii)
Tagburos (a coastal fishing community 1 km south of Sitio Honda Bay). Hair samples
were collected from the rear of the scalp (Fig. 15) from representive sub-groups totalling
35% of the SitioHonda Bay population and smallercomponents of the Tagburos and Santa
Lourdes (proper) communities. Data regarding age, sex, profession (including prior
involvementwith mining), body weight and residence history were collated by interview,
with the assistance of officials from Puerto Princesa hospital (see Appendix 1).
Following the completion of the survey, all Palawan subjects were classified into five
groups: (i) Sitio Honda Bay residents, (ii) Tagburos residents , (iii) Santa Lourdes
residents living adjacent to the PQMI site, (iv) other residents of Santa Lourdes (mainly
living west of the PQMI site), (v) ex-mineworkers from PQMI. A small control population
from Manila was also sampled for comparative purposes. Of the four ex-miners identified,
it is notable that two had previously been classified as having elevated blood Hg burdens
(c. 25 ng/ml) in the 1995 DOH survey, and had subsequently been 'detoxified at the
Puerto Princesa hospital. The age range and total number of individuals in each sample
group is shown in Figure 16.
Hair samplesof approximately2 g mass were prepared for analysis by washing repeatedly
in distilled water to remove dust and other surficialcontaminants.They were then air-dried,
cut into 1cm lengthsusing nylon scissors,weighed and transferred to 50ml graduated test-
tubes. Ten mg of V,O, and 5 ml of HNO, was added to each tube, and the samples were
left under air-reflux overnight. The following morning all samples were heated to 140°C
for 5 minutes, cooled and 2 ml of H,SO, added. After a further heating period of 15
minutes, all solid material was digested and the solutions were cooled and diluted to an
appropriate volume. An aliquot of each solution was used to determine total Hg content by
CVAFS.
Certified hair standards obtained from the EC (0.36 mgkg) and the Republic of China
(12.3mgkg) were digested in the fashion outlined above and analysed in conjunction with
the Palawan sample suite to ensure data accuracy. The Hg values obtained from 8
independent analyses of the EC reference standard were in the range 0.32 -
The corresponding range for 7 independent analyses of the Chinese standard
3 3
0.34 mgkg.
was 10.06 -

41. 0
0
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0
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0
transformation data indicatethat approximately 20%of subjects hold blood Hg burdens in
excessof 20 ng/ml. This trend is closely accordant with that previously derived from direct
blood Hg analysis of 42 subjects from Santa Lourdes and Tagburos by the DOH in 1995,
indicating an 25% exceedance of a this threshold.
5.7.5: Influence of dietary vs. residential Hg exposure: Derivation of the relative
importance of dietary, occupational and residential contributions to total Hg exposure is
critical for the accurate assessment (and, if necessary, amelioration) of toxicological risk.
From the datapresented in this study,there is no evidenceto suggest that residential factors
significantly influence the Hg body burdens of any Palawan population groups. In
particular, any exposure of the Sitio Honda Bay population as a consequence of their
residence on a mine-waste substrate can be considered negligible, given the statistical
comparability of hair Hg burdens for this group with those determined for the adjacent
coastal barangay of Tagburos. The limited significance of mining activities or mine waste
deposits on present-dav human Hg exposure is equally evident with respect to the Santa
Lourdes community living adjacent to the PQMI site, for which a mean hair Hg burden
substantially lower than that of the Tagburos coastal community has been derived. These
trends are, in turn, consistent with the mineralogical data for mine waste presented in
section 5.3, indicating that Hg in mine waste at the Sitio Honda Bay site is both
predominantlyinorganic, and held in species with extremely low bioavailability. Viewed in
conjunction,the mineralogicaland human body burden data currently available suggest that
there is no immediate requirement to re-locate the Sitio Honda Bay population (or to
otherwisemodify the structure) on grounds of Hg exposurelimitation.
In contrast to the strictly limited influenceof residentialfactors,there is strong evidencethat
diet exerts a first order control on Hg exposure within the Palawan population. The
predominanceof fish as a source of methyl Hg in the human diet has been recognised for
several decades (WHO, 1976), to the extent that up to 90% of spatial variations of Hg
burdens worldwide are explicable by reference to fish consumption (Piotrowski and
Inskip, 1981).This reflects the intense biomagnification of Hg in aquatic foodchains, often
producing enrichment factors of >30,000 in top-carnivores (shark, barracuda etc.) relative
to ambient water Hg concentrations.While the global averageHg concentrationin hair is of
the order of 2 mgkg (blood equivalent - 8 ng/ml), the ‘normal’ blood levels for high fish
consuming populations (including Italy, southern France, indigenous Canadian or
American Indians) can range from 20-80 ng/ml (e.g. Paccagnella and Prati, 1974;
Riodolfi, 1977; Clarkson, 1975;Health and Welfare of Canada, 1979).
3 9

42. 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
The WHO has provided guidelines for estimating likely hair Hg burdens in populations
with varying levels of (non-contaminated) fish consumption. These are:- consumption
once monthly = 1.4 mgkg, once weekly = 2.5 mgkg, and once daily = 11.6 mgkg.
Interviews with participants in the Palawan survey indicated that fish consumption is
generally of a daily frequency. Of the 130 subjects included in the Palawan survey, 128
displayed hair concentrations falling below the anticipated daily consumption threshold of
11.6 mgkg. The inferred body burdens of virtually all subjects can be thus be considered a
predictable and direct function of diet.
The temporal fluctuations of Hg body burden evident in one ex-mineworker sampled
during the hair survey are particularly significant with respect to the influence of dietary
vs. occupational factors. The subject concerned was detoxified at the Puerto Princesa
hospital in 1995 following the determination of a blood Hg concentration of 25 ng/ml
during the DOH survey. On treatmentthis level is likely to have fallen substantially,but has
since risen once again to >20 ng/ml (inferred from a scalp-interface hair concentration of
5.3 mgkg). This rapid post-treatment elevation of blood Hg concentration is fully
consistent with a dietary burden, with equilibrium re-established rapidly following
departurefrom hospital. This does not, in itself, raise doubt over the diagnosis of clinical
symptomsin the subject, as these are likely to be manifestationsof historical (occupational)
exposureof a much greater magnitude.
5.7.6:Toxicological implications of the recorded Hg burdens: There is no international
consensus regarding the practical ‘risk’ threshold for methyl Hg in humans. The precise
blood concentrationbeyond clinical damage occurs (often followinga long latent period) is
dependenton a complexity of factors including age, exposure duration and nutrient status
(with respect to elements such as Se). In practice, it is therefore unlikely that any single
value will prove universally applicable. Despite these uncertainties, evidence from clinical
and epidemiological studies undertakenworldwide suggeststhat the 20 ng/ml ‘action level’
currently proposed by the DOH (for use in the identification of subjects for remedial
treatment) is unusually low. Such an ultra-cautious approach may have severe cost-benefit
implications for subsequent treatment programmes, as a large percentage of the total
population will be encompassed. As noted previously (section 5.7.5), the proposed 20
ndml threshold fallswithin the ‘normal’blood concentrationrange for sizeable populations
in Europe and North America (e.g. Paccagnella and Prati, 1974; Riodolfi, 1977; Clarkson,
1975;Health and Welfare of Canada, 1979),with no toxicological effectsobserved.
Any revised blood Hg threshold or action value for use in Palawan should ideally be based
on local- and/or regional-scale dose-response datasets. In the absence of such data, the
guidelines provided in the WHO Health Criteria Document (1976), subsequently revised
4 0

43. 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
under the UNEP GEMS and MARC programmes (1981), may be of value. The latter
incorporatesdose-response data from over 300 studies conducted in Iraq, Japan, Canada,
USA and southern Europe. It concludes that an increased risk of mild non-specific
neurological damage may result from life-long exposure beyond a blood Hg threshold of
80 ng/ml. Assuming shorter exposure, risk is generally apparent beyond a higher
threshold of 200 ng/ml. Pregnant women constitute a special case, for whom a threshold
of <100 ng/ml may be more appropriate. In a 1996 Science of the Total Environment
Special Volume on mercury pollutionin Latin America, a risk threshold of 50 mg/kg in hair
(blood equivalent = 200 ng/ml) is routinely utilised.
While the determination of a toxic threshold is important with regard to the isolation of
individualsor groups at risk, it is equally critical that amelioration strategies fully account
for the Hg exposurepathways involved. Detoxification procedures (typically involving the
use of a sulphydrylreceptor) are potentially applicable for the treatment of acute exposure.
To be fully successful, however, clinical treatment must be coupled with subsequent
removal of the subject from the contaminantsource. The approach is thus inherently suited
to the treatment of occupational rather than dietary exposure, and is unlikely to provide a
long-term mechanism for reducing the imact of dietary Hg exposure in the coastal
communitiesof Palawan. In the literaturereview undertaken as a component of this study,
no instance has been recorded in which clinical detoxification has been proposed, or
applied, for the treatment of individuals/populationsexposed via fish consumption. A more
common ameliorationstrategyunder suchcircumstances involves progressive modification
of the diet (notably methods of fish preparation) through community education.
Programmes of this type have been successfully deployed among native American Indian
populations in Canada and the USA.
6: SUMMARY AND CONCLUSIONS.
From the evidence available, the declarations by the Philippine media in September 1995
regarding the occurrence of a major mercury poisoning episode on Palawan cannot be
substantiated.On the basis of the data presented in this study, the following conclusions
can be drawn:-
1:The Sitio Honda Bay jetty exerts a marked localised influence on sediment quality. The
datasets of Kapuan (1982), Benoit et al. (1994) and the MGB/BGS (1995) are accordant
in noting sedimentary Hg concentrations in excess of 100 mgkg within 100 m of the
structure. The concentrationgradients around thejetty are, however, relatively steep, and
Hg values declineto background within a distance of 400-800 m.
4 1

44. 0
e
e
0
0
e
e
0
0
0
0
0
0
e
e
0
0
e
0
e
0
0
e
a
e
e
e
0
0
e
0
0
e
2: Sediment Hg concentration data acquired by the MGB and BGS for the wider Honda
Bay environment highlight no evidence of contamination. The average interfacial Hg
concentration in Honda Bay sediments (c. 40 pgkg) lies within the global background
range. Downcore Hg profiles indicate no significant adjustment of Hg influx during the
past c. 100 years. Outwith the strictly limited zone noted above, the impact of mining
andor coastal tailings disposal can be considerednegligible.
3: Data produced by the MGB and BGS for waste material from the Sitio Honda Bay
structure indicate that the total Hg content is variable, with values ranging from 30-340
mgkg. The down-profile distribution of Hg is characterised by a systematic decline of
concentration with depth. There is unsubstantiated evidence that garden topsoil imported
onto the Sitio Honda Bay jetty (with a relatively high organic content) may actively
accumulateHg to levelsexceedingthose of the underlying waste.
4: The speciationor geochemicalform of Hg in the SitioHondaBay waste (and in the Hg-
enriched sediments adjacent to the structure) is overwhelmingly dominated by inormnic
Hg-phases. Onshore and nearshore methylation rates for Hg appear low. Cinnabar is not
the sole inorganic host, as c. 90%of the total Hg present resides in fine particulates of low
specific-gravity. Microprobe analyses of the <20 pm fraction of one Sitio Honda Bay
waste sample have shown a substantial proportion of this non-sulphide Hg to occur in
ferric oxyhydroxide complexes which, in turn, are stronglybound to clay mineral surfaces.
The bioavailabilityof Hg (and other heavy metals) in this form is extremely limited.
5: Analysis by CVAFS of filtered (0.45 pm) surface- and groundwater samples from the
Tagburos-Santa Lourdes area (including the PQMI site) has indicated no detectable Hg
contamination. All aquifer and stream water samples yielded Hg values of 40 ng/l or
below, and thus fall within the global background range. Such low concentrations are
surprising given the highly mineralised, geothermally active setting involved. The
sporadicallyelevated Hg values (up to 4 pg/l) reported for Santa Lourdes groundwaters in
certain previous studies (notably the dataset supplied to the MGB by SGS Laboratories) are
of doubtful credibility due to the samplingand analyticalproceduresinvolved.
6: The Hg burdens of 60 fish samples (10 each of six species) from the inner and outer
sectors of Honda Bay fall within the ranges typically encountered for comparable species
worldwide. The mean Hg burdens for all species fall below the US-EPA marketing
threshold of 0.5 mgkg. No recorded value approaches the Minamata range. The values
recorded show accordance with data acquired for Honda Bay fish by EMB and University of
4 2

45. 0
e
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
e
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
the Philippines researchers. All depict low or moderate Hg burdens when expressed on a
common (ie. wet weight)basis. To date, no evidence has been provided to justify any bay-
wide restriction of fishing activities(or fish consumption).
7: Samples of Pernu viridis (green mussel) recovered from a site 10 m off the Sitio Honda
Bayjetty exhibit Hg enhancement in soft tissues to levels within the Minamata range (max.
21 mg/kg dry weight). Attendant toxicological stress has been inferred from a low NRR
capacity in individual cells from these samples. Comparative analyses of Perm viridis
specimens from Canon Island (5-6 km offshore) showed tissue Hg burdens to lie
exclusively within the global background range (1-2 mg/kg dry weight). Ecotoxicological
tests for this populationproduced no evidence of cell dysfunction. These trends concur with
sediment-based evidence (1 & 2 above) indicating the strictly localised impact of the jetty
structureon the marine environment.
8: A comprehensive survey of Hg body burdens in 130 Honda Bay subjects based on hair
analysis has highlighted a universally high level of Hg exposure relative to a small control
population from Manila. It is, however, extremely unlikely that this exposure level is
reflective of geologicalfactors or mining activities.Statistical comparison of the Sitio Honda
Bay, Tagburos and Santa Lourdes (proper) populations failed to significantly discriminate
the former two groups, from which it can be concluded that the Sitio Honda Bay population
is not subject to elevated Hg exposure as a consequence of residence on the Hg-enriched
substrate. Population resettlement on health grounds is therefore probably unwarranted.
Estimated mean blood Hg values for the five Palawan sample groups range from 8.8-17.6
ng/ml, with a maximum individual value of 74.1 ng/ml. The mean and median values for all
groups are typical of populations consuming fish at a daily frequency. No alternative
mechanism of exposure need be invoked. Data regarding the precise blood Hg threshold
associated with the onset of toxicologicalrisk are equivocal. There is, however, virtually no
evidenceof appreciablerisk at blood concentrations of e80 ng/ml, irrespective of exposure
duration.
9: Strategies for ameliorating Hg-induced health hazards must take account of both the
clinical symptomspresentedand the mechanism of exposure involved. In cases of acute Hg
exposurefrom a residential or occupationalsource (for example, through former employment
in a mine), post-exposure detoxificationmay be beneficial. The approach has strictly limited
applicability,however, in instances of dietary exposure, for which a strategy of progressive
food supply modification is routinely adopted.
10: The above conclusions are substantially based on a single field sampling programme,
conducted in December 1995. This short survey constitutes no adequate substitute for longer
4 3

46. term monitoring, which will inevitably provide the key to a more comprehensive
understanding of the sources,environmentalbehaviour and toxicity of Hg in Honda Bay and
beyond.
7: ACKNOWLEDGEMENTS
This study was funded by the UK ODA through the diversion of resources from
Engineering Division Technology Development and Research (TDR) programme R6226
(Mitigation of Mining-Related Mercury Pollution Hazards). Logistic support and field
guidance was provided by staff of the Philippines Department of Environment and Natural
Resources (Mines and Geosciences Bureau) and the Puerto Princesa Hospital, Palawan.
University of the Philippines researchers Ms. Grace Doming0 and Mr Mike Reyes
participated enthusiastically in all aspects of the field programme. Discussions with Dr
G.S. Jacinto (Universityof the Philippines)and Dr A. Socrates (Provincial Health Officer,
Palawan) were invaluable throughoutboth the design and execution phases of the survey.
8: REFERENCES:
Benoit, G., Schwantes, J.M., Jacinto, G.S. and Goud-Collins, M.R. 1994: Preliminary
study of the redistribution and transformation of HgS from cinnabar mine tailings
deposited in Honda Bay, Palawan,Philippines.Marine PollutionBull. 12,754-759.
Clarkson T.W. 1975:Exposure to methyl Hg in Grassy Narrows and White Dog reserves.
Interim-report., US-EPA.
Health and Welfare of Canada. 1979: Task force on organic mercury in the environment.
Grassy Narrows and White Dog reserves,Ontario.Dept. National Health and Welfare,
Ottowa, Canada.
Kapuan, A.F., Kapuan, P.A., Tan, E.C. and Vercelez, F. 1982: Total mercury in water
and sediments from the Honda Bay area in Palawan, Phil. J. Sci. 3, 135-144.
Kershaw, T.G., Clarkson, T.W. and Dhahir, P.H. 1980: The relationship between blood
levels and dose of methylmercury in man. Arch. Environ. Health, 35,28-36.
Krauskopf, K.B. 1979: Introductionto Geochemistry.McGraw Hill, 617 pp.
Paccagnella, B., Prati, L. and Bigoni, A. 1973: Studio epidemiologico sur mercurio nei
pesci e la salute unama in un isola Italianadel Metiterraneo. Ig. Mod. 66,479-503.
4 4

47. 0
0
0
0
0
0
e
0
0
0
0
0
0
0
a
0
0
0
0
0
0
0
0
a
0
0
e
a
0
0
0
0
Paccagnella, B. and Pratti,L: 1974:Total mercury in blood and hair of Italian people. Ig.
Mod. 67, 369-30.
Piotrowski, J.K. and Inskip, M.J. 1981: Health effects of methylmercury. MARC,
University of London. 82 pp.
Riodolfi. M. 1977: Further epidemiological study of Hg levels in fish and human blood
and hair. Ig. Mod. 70, 169-186.
United Nations Development Programme: 1986: Geology of Central Palawan, Technical
Report no. 6, DP/UN/PHI-79-004-6. UNDP, New Uork, 56 pp.
Weeks, J. and Williams, T.M: 1995: A simple ecotoxicological field test to determine
mining-related heavy toxic trace element stress.Ecotoxicology-(inpress).
World Health Organisation 1976:Environmental Health CriteriaDocument 1:Mercury.
WHO, Geneva.
World Health Organisation 1981: Revised Health Criteria Document: Mercury, WHO,
Geneva.
4 5

48. 0
e
0
0
0
0
a
0
0
0
0
0
0
0
0
0
0
a
0
0
0
0
0
0
0
a
a
0
0
0
0
0
0
0
APPENDIX 1:
Descriptive information for all subjects of Manila and Palawan groups from
whom hair samples were collected for Hg analysis. Note that the code JP is
utilised in place of SHB to depict the SitioHonda Bay group.
4 6

49. S I T 1 0 HOflDA B A Y
C H I L D R E H C O D E J r
f l l 3 U E S E X
1 R d r i a n D e l a C r u r n
Z L a a r n i B o j o s F
3 J c r r l c E r c o b a n c z n
f J n y b n l d o C a p a c h o n
S n a r l a n o K a t h i r i n e R l F
6 n a r i a n o K r i r t c n c R l l F
7 D a u i d X r i s t i n c
B U n i c o 6 i r l i c
fiDULT C O D E
9 E l c n a h g u i l a r
l e ~ o g e i i oU l l l a n u e u a
1 1 K z i h i l l n V i l i h n u c v a
lZ 6 i n a F c U i l l a n u c u a
1 3 R a n d y V i 1 l a n u c u a
1 4 ~ n n a l f z a n a y o l i n o
1 S f i l f r t d a K a g o l i n o
1 6 H i c o l a s A l a r o
1 7 s i r n A l n r o
1 8 J u d i t h A l n r o
1 9 L o l i t a R e y c r
2 8 P c d r o G r a p a n
Z l A r s e n i a R c q u i n t o
Z Z L o c t l y n D a n a o
2 3 F r c d D a n a o
Z t F o r d i u t s D a n n o
2 5 4 n g e l i t a G c j o n
2 6 T i t o G c j o n
27 B l o r i a C o r t e r
Z R V i c t o r i o H o r c n o
2 9 J o c p n n U n i c o
3 0 J o c e l y n U n i c o
3 1 U a l e n t f n a U n i c o
3 2 J o s i c B u n g a r
3 3 F e l l n a U a l l r d o r
3 4 J u l l t o 6 o n n a l r r
3 5 R y a n U u l l a g
36 J a y h p o l i n a r
3 7 R o l a n d o H a r a p a o
3 8 E r l l n d a n a r a p a o
3 9 F c r n a n d a f i p o l i n a r
i i i i i a r i t c s i i c i a C r u z
1 1 R n i t a D t l a C r u z
- -. - .. .
F
F
J P
F
n
F
F
tl
F
n
n
€
F
F
K
€
F
n
tl
F
n
F
n
n
F
F
F
P
n
n
n
n
F
rr
t
P
-
R 6 E
7
6
7
7
6
b
6
2
5 7
5 1
3 4
17
1 5
2 4
6 7
O C C U P A T I o n U T . K B . h D D R E S S
S i t i o H o n d a B a g )
S I t i o H o n d a B a y
S i t i o H o n d a B a y
S i t i o H o n d n B a y
S i t i o H o n d h B a g
S i t i a H o n d a B a y
S i t i o H o n d a B a y
S i t i o H o n d a B a y
S t o r e O u n c r 5 8 . 8 S i t i o H o n d a R a y
F i s h e r m a n 19.0 S i t 1 0 H o n d a B a y
H o u s c k c c p c r 5 2 . B S i t i o H o n d a B a y
H o u r c k c c p c r S B . 0 S i t i o H o n d a Hay
F i f h r r u a n 5 2 . 0 S i t i o H o n d a R a y
H o u s e k e e p e r 5 0 . B S i t f o H o n d a B a y
F i s h e r m a n 5 5 . 0 S i t i o H o n d a B a y
2 5
2 7
4 8
Z B
7 t
3 1
10 m o s
2
2 5
2 6
5 3
5 R
3
29
5 s
2 5
5 3
1 2
7
2 1
3 6
3 1
Z t o r r O u n c r
S t o r e O u n e r
H o u s r k e e p c r
f i s h c r n r a n
H o u s r k c c p c r
H o u s e k e e p e r
6 6 F a r a c r / K i n c U o r k 7 8 . 0 S i t i o H o n d a B a y
H o u s c k t c p c r
F i n l i t r n a n
S t o r e O u n e r
F i s h t r n a n
S t o r e O u n e r
H o u s c k c c p c r
H o u s r k c c p c r
S t o r e O u n t r
f i s h c r m a n
f l r h c r a a n
H o u n e k e e p r r
* 3 . 8 S i t i o
3 8 . 6 S i t i o
4 6 . 9 S i t j o
5 1 . 5 S i t i o
3 3 . 2 S i t i o
5 4 . 5 S f t i o
18.0 S i t i o
1 3 . 8 S i t i o
l B . 9 S i t l o
s4.5 S i t i o
6 8 . 8 S f t i o
5 i i . R S i t i o
1 2 . 5 S i t i o
50.0 S i t i o
5 1 . 8 S i t i o
4 9 . 8 S i t i o
58.0 S i t 1 0
18.0 Sitio
16.6 Sitio
* 6 . 0 S i t i o
b 0 . B S i t i o
5 1 . 5 S l t i o
H o n d n
n o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
2 2 P u m p B o a t O p e r n t 5 6 . 8 S i t i o H o n d a B a y
i i S t u d e n t 45.6 S i i l o ~ o n d aB a y
5 B . B S i t l o H o n d a B a y58 H o u r c k c e p t r
... . - . .

50. 0
ni z n a r l o n D a g a n t a
0 13 J o h n l J n i c o
n
ni i f l l c h a c l n a n a l o
0 i 5 B c n J i e Q u i u a r
4 6 f i b n c r Q u l u a r
n
n
1 7 D i o n i t o G o n r a l e r n
+ 0 n a r i s s a H c r r c r a F
5 3 R l d r l n f i s t a c a a n n
5 8 J e f f c r r o n O t r a r a n n
5 1 J a m e s f i r c h i c O t s a r a n n
0
S Z C h r i s t o p h c r C a ~ ~ a c h oH
5 3 f i l b e r t h l u t a y a F
0 5 1 E l y B c r a m c n
2 4
1 6
9
8
1 2
b
1 8
1 1
1 2
9
1 3
1 0
1 0
F i s h e r r a n
S t u d e n t
S t u d c n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
5 5 n a r i t e s H e r r c r a F 1 2 S t u d e n t
5 6 K r i s t i n a n a n a b a t F 1 2 S t u d e n t
0 5 7 n a r i a l e n B c r a r c F 9 S t u d e n t
5 8 S h e e n a A f c a t a a n F 1 0 S t u d e n t
F - l e D a y C a r e U o r k c r
0
I 0 1 E l f r a b c t h P u l a n c o
1 8 2 F c d c r i c o T u ~ n o g n 8 5 f a r r e r / S k i n L e s s
o n L e g s
O S A t t T R L G U R D E S
I C h r i s t i a n A l o n s a g a y n
0 Z E r u i n J a m a n d r c n
~i R o s a l i e A l o n s n y a y F
0 4 e l l a n ~ l l o n s a g a y n
5 S a 1 u a d o r A n a n o n
0 6 n a r i c c l D u c o r i n F
0
7 E ~ i l y nC e l e d o n i o F
8 R u s s c l l P a l a c s K
0 9 K a t r i n a h i o n s a g a y F
1 0 J a k c D o r r c r o n
0 1 1 n a r y J a n c S i n o y F
0
0 1 4 J c s r a n f I l o n s a g a y F
0 1 8 P i a n o n i s
0 1 9 T e r e r a f I m a n o F
0 ~ i i i u i yj a g i i a s n a r i n a s
1 2 B e n j i c B o q u c n a n
13 G l c n d a B o q u e n a F
1 5 D o n n a D o r r e r o F
1 6 ~ e c e i y n~ a c o s a F
1 7 B l e n d c l C a s u p a n a n F
F
2 8 C a t h e r i n c B o n t o g o n F
-
2 2 R u b y l y n F u c g o
0
F
9
a
1 1
12
1 1
12
1 2
8
1 2
1 2
1 1
1 2
1 0
1 1
1 4
1 1
9
9
8
1 1
i i
1 1
S t u d e n t
S t u d c n t
S t u d e n t
S t u d e n t
S t u d c n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d c n t
S t u d e n t
S t u d e n t
S i t u d e n t
S t u d e n t
S 0 . B S l t i o
5 5 . 0 S i t i o
3 6 . 0 S f t l O
2 5 . 8 S i t t o
3 0 . 0 S i t 1 0
1 6 . 6 S i t i O
2 5 . t 3 i t i o
2 7 . 0 3 l t i o
3 3 . 8 S i t i o
2 5 . 9 S i t i o
3 7 . 0 S f t i o
2 2 . 0 S i t i o
2 5 . 0 S i t t o
3 0 . 0 S i t i o
3 S . 0 S i t i o
2 1 . 0 S l t i o
z1.0 S i t i o
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
H o n d a
7 2 . e H a i n i t
5 5 . 0 H a i n i t
2 3 . 6 S t a L o u r d c s
2 7 . 8 S t a L o u r d r s
2 s - 3 S t a L o u r d e r
2 3 . 6 S t a L o u r d c s
2 7 . 7 S t a L o u r d c s
3 3 . 0 S t a L o u r d e s
2 5 . 8 S t a L o u r d e r
S t a L o u r d c s2 2 . e
2 7 . 0 S t a L o u r d c s
3 0 . 0 S t a L o u r d c r
2 2 . ? S t a L o u r d e s
S t a L o u r d c s
2 5 . e S t a L o u r d c s
2 6 - 0 S t a L o u r d e s
4 0 . 0 S t a L o u r d e s
2 6 . 0 S t a L o u r d e s
t a . 6 S t a L o u r d c s
1 9 . s S t a L o u r d e s
20.9 S t a L o u r d e s
3 3 . 6 S t a L o u r d e s
4 3 . 6 S t a L o u r d r s
S t a L o u r d e s3 0 . 0
2 a - 0
0
0

51. ~ , H * L O U R D E S ( C o n ? C O D E S L
*
0 2 , R o s a F e L a n t r c l l a F 1 1
0 2 7 C h e r y l H l c g a r t- 1 2
0 2 9 R o b c r t o 6 a b r i c l n 1 2
F 1 3z 3 ~ p r l ~ y n~ a c o s a
Z S n a r l c c l n c j o l l o F 1 3
R c z c l E a r l a s F 1 2
28 J r f f r c y L a u c r o n i l l a K 1 2
3 8 ti i n o D a s n a r 1 n a s n 1 3
F 5 0
S t u d c n t
S t u d e n t
S t u d c n t
S t u d c n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d e n t
2 0 . 6
2 8 . 6
3 0 . 0
3 2 . 7
5 3 . 6
4 0 . 0
2 5 . 8
3 0 . 0
5 6 . 0
S t a L o u r d c s
S t a L o u r d c s
S t a L o u r d c r
S t a L o u r d c r
C c n t r o
n a t a h i m ik
n a t a h ie ik
C c n t r o
C c n t r o
S T A L O U R D E S n f 3 T h H I t l I K ( N E A R H I H E )
.C O D E S L n
n
Z n e l u l n D a n a r o n
3 H a r c o L a g p a n n
4 6 c r a l d L a n g o r a y a n n
6 S u s a n T a y l o r F
5 J o b c r I y L a u r o n l l l a n
7 J o b e r l y L a n g o r a y a n F
8 n a r y firm S c r a l d c F
a
9 J o h n n n u r i c c U h n y n
0
S E D a n i e l T a y l o r n
. i t b C U R O S - S I T 1 0 A P L A Y R
C O D E T G
1 0
1 8
1 8
1 1
1 0
1 0
Y
3
S Z
S Z
S t u d c n t
S t u d e n t
S t u d e n t
S t u d c n t
S t u d e n t
S t u d e n t
S t u d e n t
S t u d c n t
S t u d c n t
S t u d e n t
2 5 . 0
2 5 . 0
2 4 . 0
2 6 . 0
2 7 . e
2 3 . 0
2 s . 0
2 3 . 0
2 0 . 0
3 1 . 0
n a t a h i n t k
n a t a h ia I k
n a t a h i m i k
R a t a h i s ~ i k
n a t a h i a i k
n a t a h i n i k
t l a t a l ~ l n i k
H a t a h I n i k
n a t a h l a 1 k
n n t a h i m i k
1 D n n t c G a l l c g o
0 2 A r i c l G u h c l d c
3 R c r e l T a m p o n
4 J o c g G a l l c g o
0
5 R a n i 1 J U n n n
0 7 T c o f e i a G a i i c g o F
6 J e n u e G a l l e g o F
8 E l c o t c r i o S e u a s i o n
n
l e F l o r e n c i a P a l o r o P
1 1 C r i s t i n a S u r d i l l a F
0 1 2 C o n c c p c i o n S u r d i l l a P
1 3 n a r i a n c B c n t i r o s o F
1 4 n i c a B e n t i r o s o F
Z B F i s h c r n a n
2 8 F l r h c r a a n
1 8 F i r h c r n a n
1 8 F i s h e r m a n
1 6 F I s h c r e a n
z
4 s H o u s e k e e p e r
67 f i r h e r m a n
6
* 0 H a u s e k e e p e r
5
3 2 H a u s c k c c p c r
1
2
2 5
st, H o u s c k c c p c r
5 S t u d c n t
6 1 . 0
6 5 - 8
s s . a
6 8 . 8
6 0 - 0
5 . 9
S 0 . B
6 0 - 6
1 6 . B
4 8 . e
1 7 . 0
s a .e
9 . 0
1 2 - 0
5 0 . 0
5 0 - 0
2 8 : 0
T ~ g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o r
T ~ g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o s
T a g b u r o r
T a g b u r o s
T a g b u r o s
T ag b U r o r
L e n g t h
S t a y
S / B
S / B
8 y r s .
S / B
7 y r s .
S / B
S / B
1 0 y r s
S / B
8 y r r .
S / B
1 6 y r s
6 1 0 s .
6 m o p .
6 m o p .
1 0 y r s
3 / B

52. 0
0
0
0
0
e
0
0
e
0
0
0
0
0
0
0
e
0
0
0
0
0
0
e
0
a
0
0
0
0
0
0
Name
TG (cont)
18 VicenteLapis
19 Pedro Lapis
20 Feliza Rolano
21 Petra Lapis
22 AmbrosiaMaratas
23 EmmaDopeno
24 Ma. April Luna
25 CrisantaOruta
EX
1 FedericoMumar
2 FedericoVejana
3 Unknown
4 AidoMedina
CON
1 ShirlinaOreas
2 James Oreas
3 Bettina Gonzales
4 Jocelyn Domingo
5 MichelleDomingo
6 Nelsie Garcellan
7 RamonSingh
Sex
M
M
F
F
M
F
F
F
M
M
M
M
F
M
F
F
F
F
M
Age Occupation Wt
56
46
28
55
55
9
8
48
65
70
70
65
36
4
12
34
3
19
36
fisherman
fisherman
housekeeper
housekeeper
fisherman
student
student
housekeeper
ex-miner
ex-miner
ex-miner
ex-miner
dentist
-
-
housewife
-
mechanic
52
59
45
46
60
18
17
43
-
-
-
-
-
25
30
65
20
40
65
Residence Period
Tagburos
Tagburos
Tagburos
Tagburos
Tagburos
Tagburos
Tagburos
Tagburos
(detoxified)
(detoxified)
(wheelchair)
-
Manila
Manila
Manila
Manila
Manila
Manila
Manila
12yrs
11yrs
8 yrs
10yrs
15yrs
4 yrs
2 yrs
9 yrs

53. 0
0
a
0
0
a
0
a
0
0
0
0
0
e
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
I,
APPENDIX 2:
Total Hg concentration data for all subjects included in the Palawan hair
survey. Note that the code JP is utilised in place of SHB to depict the Sitio Honda Bay
group.
4 7

54. O A G G LAB NO. 8942
4
JP 12 ~ 0.1024 5.68 6.04
JP13 1 0.1023 6.16
JP 14 0.1398 3.77
JP 15 0.1016 6.55
JP 16 0.1022 2.78
JP17 I 0.1373 0.40
~
SAMPLE , WEIGHT] PPM repeat value
JP 1 ' 0.1110 1.39
JP 2 0.1059 2.40
JP 3 1 0.0721 4.34 i
JP27 j 0.1057
JP28 ~ 0.1118
IJP 4 i 0.1015 I 6.69 I
3.61 1
8.32
IJP 5 j 0.1047 1 3.28 I 1
JP32 ~ 0.1159
JP33 1 0.1174
IJP 6 1 0.1092 ~ 3.56 1 1
2.14
3.14 1
IJP 7 ~ 0.1444 1 6.77 1 1
JP 35
JP 36
IJP 8 ~ 0.0903 1 2.49 1 1
0.1209 ~ 6.53
0.1150 i 7.55
IJP 9 ~ 0.0547 ~ 1.07 1 1
JP 39 1 0.1286 2.38
JP40 j 0.1047 1.16
IJP 10 ! 0.1124 1 10.93 1 1
~~
IJP 11 1 0.1128 1 3.78 1 1
JP 41 0.1201
JP 43 1 0.1243
~ ~ 4 2i 0.1040
JP44 1 0.0119
1.64
3.97
2.87
<0.10
lJP18 j 0.1157 I 0.72 1 1
2.65
JP20 1 0.1164 ~ 10.28
IJP 21 1 0.1007 1 2.35 I 1
IJP 22 0.1042 1 2.00 1 1
IJP 23 1 0.0692 1 3.01 1 1
IJP24 i 0.1017 1 2.77 1 1
IJP25 ~ 0.1102 ~ 3.36 1 1
1JP26 I 0.1259 1 10.02 1 1
IJP38 1 0.1131 1 4.04 1 1

55. AGG LAB NO.8942
JP 52 0.1012 18.54
JP 53 0.1 287 6.92
JP 54 0.1102 , 7.45
SAMPLE 1 WEIGHT/ PPM 1 repeat value
JP 45 0.0461 1 4.18 i
JP 56
JP 57
i
JP46 ! 0.0878 1 6.09 1
0.1250 ' 4.91
0.1 073 5.67
JP 47 1 0.0146 1 3.83 1
JP 102 1 0.0506- I
I
JP 48 1 0.1072 1 3.24 1
2.88
JP49 i 0.1063 1 1.67 1
JP50 1 0.1152 1 16.58 1
JP 55 1 0.1135 I 3.70 1
I I
JP 101 1 0.1028 1 2.35
SAMPLE ! WEIGHT^ PPM i
1
GSH-1 1 0.10041 0.32 ,
GSH-1 ~ 0.101OI 0.32 I
GSH-1 j 0.1OOOI 0.34 I
GSH-1 I 0.1006/ 0.32 ~
GSH-1 ~ 0.09981 0.32 I
GSH-1 I 0.101OI 0.32 I
GSH-1 ~ 0.09951 0.34 1

56. e
AGG LAB NO. 8942
e
e
0
e
0
0
e
e
0
0
0
e
0
0
0
0
I,
0
0
0
0
0
0
0
0
0
0
0
0
I)
0
SL 2 1 0.1020
SL 3 i 0.1072
SAMPLE I WEIGHT i PPM I reDeat value I
3.17
1.46
CON 1 i 0.0506 1 1.07 1 i
SL 4
SL 5
CON2 ~ 0.0737 1 0.70 1 1
0.1051 ~ 1.78
0.1463 1 0.98
CON 3 I 0.1280 1 0.49 1 1
SL 6 1 0.1528
SL 7 j 0.1030
CON 4 i 0.1005 1 0.37 1 1
3.83
2.98
CON 5 j 0.1010 1 0.33
CON 6 1 0.1073 I 0.98
SL 21
SL 22
SL 23
CON 7 ~ 0.1094 1 0.48 1 1
0.1 502 1.69
0.1 003 1.50
0.1 554 2.97
I I !
EX 1 I 0.1264 1 5.29
EX 2 1 0.1089 1 5.31 1 5.94 1
EX 3 1 0.1170 1 1.05 I 1
EX 4 I 0.1115 1 1.51 1 1
SL 1 I 0.1091 1 1.31 1 1
SL 8 i 0.1143 1 1.76 1 1
SL 9 ~ 0.1224 1 1.28 1 1I
SL 10 1 0.1148 j 3.62
SL 11 1 0.1363 1 3.95
SL12 I 0.1232 1 3.45 I
SL 14 1 0.1643 1 1.91 1 1
SL15 i 0.1215 1 3.92 1 1
SL16 I 0.1094 1 3.34 1 1
SL17 ~ 0.1128 1 1.44 1 1
SL18 I 0.1012 ~ 1.06 1 1
sL19 i 0.1142 I 1.22 I 1
SL20 I 0.1096 1 2.09 I 1
SL 24 0.1223
0.1 008
SL 26 0.1 124
SL 27 0.1261 1 0.92
SL28 1 0.1579 1 2.10 1 1
SL29 1 0.0665 1 3.25 1 1
3L30 ~ 0.1162 1 2.46 1 1
3L31 ~ 0.1048 1 2.09 1 2.68 1

57. 0
0 AGG LAB NO. 8942
TG 11
TG 12
0
0
0
0
0
0
a
a
0
0
0
0
0
0
0
0
e
0
0
0
0
0
0
0
0
0
0
rn
rn
D
0.1140 j 3.58 ~
0.1138 4.58 j
SLM 2 0.0759 1 2.30 ~
TG 13
TG 14
TG 15
SLM4 1 0.0922 I 2.93 I 1
0.1232 1 0.72 I
0.1180 1 0.78 ~
0.1445 j 1.86 ~
SLM5 1 0.1159 I 2.27 ~ 1
TG 17
TG 18
SLM 6 I 0.1097 1 2.46 I 1
0.0782 ~ 2.91 ~
0.1113 1 5.74 ~
SLM7 I 0.1445 1 1.83 1 1
SLM 10 0.1 336 3.54
TG 1 I 0.1199 1 2.08 1 1
TG 2 1 0.0593 1 5.97 1 1
TG 3 1 0.1171 1 5.52 1 1
TG 4 I 0.0386 I 1.87 i 1
TG 5 1 0.1084 1 3.25 1 1
TG 6 I 0.1040 1 8.00 1 1
TG 7 1 0.1142 I 5.58 1 1
TG 8 1 0.1291 1 7.25 1 1
TG 9 1 0.1054 1 5.08 1 1
TG10 1 0.1170 1 3.02 1 1
11
TG16 1 0.1104 1 2.87 ~
11.12
TG 21 0.1 322
TG 22 I 0.1209 5.51
TG23 I 0.1356 1 1.92 1 1
TG 24 1 0.1094 I 1.91 i 1
TG 25 I 0.1239 1 4.63 1 1