EXPERIMENT 4: Environmental Toxicity

Test

By: Marlisa SauNur Hayati YusoffNorfarrahdilah AmirSiti Salwa Abdullah

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

Procedure

Aquatic animal (fishes)

12 conical flask (250ml) Shaker

Balance Chemical solution Fresh water

Tweezers

Materials

Methods

The dose at which the biomass is 50% of the control value was determined. This is called ED50.

The graph of number fishes died against concentration of chemical solution was plotted.

The data was recorded at tabulated data.

The fishes that died are calculated within 15 minutes.

The condition of fishes are observed for 15 minutes.

Then, 10 fishes are put into the prepared flasks.

Each of the solutions were calculated using the same formulae for the other concentration.

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

The flask was labeled with eight different concentrations of each chemical solution.

RESULT :

Calculation

Initial Volume (Vi) = ?Final Volume (Vf) = 200ml

Initial Concentration (Mi) = 0.1 MFinal 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

Observation

Fishes at 0.004 M

Fishes at 0.03 M

Fishes at 0.05 M

Concentration of chemical solution

(Malathion)

Volume of Malathion

needed (Vi)

Total fishes Total fishes that died within 15

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

Table 1

Graph 1

1 2 3 4 5 6 7 80

20

40

60

80

100

120

Number of fish died against Concentration of Malathion

Total fishes that died within 15 minutes

Concentration of Maklathion

Num

ber o

f fish

die

d (%

)

LD50

DiscussionIn 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.

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.

QUESTIONS1. 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.

3. Do you think the chemicals will give a similar toxicity response if tested to human? Why?

No. this is because mammals have greater carboxylesterase activity relative to levels in insects. This enables mammals to degrade malathion more quickly than it is oxidized to the malaoxon form. Higher vertebrates therefore detoxify and excrete malathion more readily than do insects. This accounts for the relatively low toxicity of malathion to mammals. Greater carboxylesterase production with consequent increased detoxification of malathion appears to be the underlying mechanism in resistant insect pests.

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.

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.

Moral Values

PLEASE LOVE THE ENVIRONMENT & KEEP THE BEAUTY OF AQUATIC LIFE

….THANK YOU…