EXPERIMENT 4: Environmental Toxicity TestBy: Marlisa Sau Nur Hayati Yusoff Norfarrahdilah Amir Siti 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
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.
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
Observation Fishes at 0.05 MFishes at 0.004 M Fishes at 0.03 M
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
Graph 1 Number of fish died against Concentration of Malathion 120 100 80 LD50Number 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
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?
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.
CONCLUSIONAfter 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 ValuesPLEASE LOVE THE ENVIRONMENT & KEEP THE BEAUTY OF AQUATIC LIFE ….THANK YOU…