1. EXPERIMENT 4:
Environmental Toxicity
Test
By: Marlisa Sau
Nur Hayati Yusoff
Norfarrahdilah Amir
Siti Salwa Abdullah
2. Objective
To understand the concept of dose and
response
To determine ED50 for this pesticides
Become aware of toxicity potential from the use
of chemicals such as pesticides and other toxic
household products
4. Methods
The flask was labeled with eight different concentrations of each chemical solution.
The volume of chemical solution needed was calculated to make final volume of solution to
200ml with first concentration which is 0.004M using the formulae M1V1=M2V2
Each of the solutions were calculated using the same formulae for the other concentration.
Then, 10 fishes are put into the prepared flasks.
The condition of fishes are observed for 15 minutes.
The fishes that died are calculated within 15 minutes.
The data was recorded at tabulated data.
The graph of number fishes died against concentration of chemical solution was plotted.
The dose at which the biomass is 50% of the control value was determined. This is called ED50.
5. RESULT :
Calculation
Initial Volume (Vi) = ?
Final Volume (Vf) = 200ml
Initial Concentration (Mi) = 0.1 M
Final Concentration (Mf) = 0.004 M
Using this fomulae to calculate Vi :
MiVi = MfVf
(0.1M)(Vi) = (0.004M)(200ml)
(Vi) = (0.004M)(200ml)
(0.1M)
(Vi) = 8ml
6. Observation
Fishes at 0.05 M
Fishes at 0.004 M
Fishes at 0.03 M
7. Table 1
Concentration of Volume of Total fishes Total fishes that
chemical solution Malathion died within 15
(Malathion) needed (Vi) minutes
0.004 M 8 ml 10 0
0.006 M 12 ml 10 3
0.008 M 16 ml 10 1
0.010 M 20 ml 10 5
0.020 M 40 ml 10 5
0.030 M 60 ml 10 10
0.040 M 80 ml 10 5
0.050 M 100 ml 10 7
8. Graph 1
Number of fish died against Concentration of Malathion
120
100
80 LD50
Number of fish died (%)
60
Total fishes that died within 15 minutes
40
20
0
1 2 3 4 5 6 7 8
Concentration of Maklathion
9. Discussion
In this experiment, we are carried out
toxicity test in order to examine the sensitivity
of common aquatic life to different
concentration of perticides.
This test relies upon biomass production over
time in the presence of increasing
concentrations of the selected pesticides.
10. The LD50 is a crude approximately of a
chemical’s toxicity.
The dose at which 50% of the population die
is called the lethal dose 50 (LD50).
From the data result, we can said
that, increase in concentration of Malathion
solution, the more fishes was died in short
period within 15 minutes.
We estimated the value of LD50 is 0.01 to
0.02 M.
11. QUESTIONS
1. Which chemical shows the highest toxicity?
The chemical that shows the highest toxicity
is when the concentration of Malathion in
0.03 M.
2. How does the tested chemical can enter
human body?
Tested chemical can enter the human body
via skin contact, ingestion and inhalation
exposure.
12. 3. Do you think the chemicals will give a similar toxicity
response if tested to human? Why?
13. 4. Do you think the toxicity of the chemicals is
similar in the real situation outside the
laboratory? Why?
No, this is because only small water volume
used in the laboratory while in real situation
outside, the Malathion enter into river water
through infiltration and ground water. The
process is not in constant rate and the river
water is always flowing.
14. CONCLUSION
After doing this experiment, we got better
understanding about the concept of dose and
response.
Each concentration of chemical perticides give
effects to aquatic life.
As the concentration of Malathion used
increase, the more faster the fishes was died
within 15 minutes.
As the more toxic concentration, the more
number of fishes will died.
