Skip to 0 minutes and 10 seconds The positive effects of using pesticides include crop protection, preservation of food and materials and prevention of vector-borne diseases. However, pesticides are designed to be toxic. Improper use of pesticides can be harmful to pesticide workers and can cause pesticide residue contamination in food. Environment and ecosystems are also affected by using pesticides. The next point I am going to talk about is Health Risk Assessments of Pesticides. In order to minimize the health risk of pesticides, current regulations require that new pesticides must be evaluated before they can enter the market and existing pesticides must be re-evaluated periodically to ensure that they continue to meet the appropriate safety standard. Risk is dependent on toxicity and exposure.
Skip to 1 minute and 19 seconds Pesticides can enter the body through the mouth, the eyes, the skin, or the nose. So toxicity tests are carried out to determine the health effects by different routes of exposure. Acute toxicity of a pesticide refers to the chemical’s ability to cause injury to a person or animal from a single exposure. The results of acute toxicity test is usually expressed as LD50 lethal dose 50
Skip to 1 minute and 58 seconds From this table, we can see that pesticides are categorized on the basis of their relative acute toxicity. The LD50 values are based on a single dosage and are recorded in milligrams of pesticide per kilogram of body weight of the test animal. The LD50 values are useful in comparing the toxicities of different active ingredients. WHO established five Toxicity Categories for acute hazards of pesticide products by use of lethal dose data. The lower the LD50 of a pesticide, the greater its toxicity to humans and animals.
Skip to 2 minutes and 48 seconds The five toxicity categories, from Ia to U are category Ia is extremely hazardous, category Ib is highly hazardous, category II is moderately hazardous, category III is slightly hazardous, and category U is unlikely to present acute hazard. Extremely hazardous pesticides have already been prohibited to use in many countries including Taiwan. So pesticides used now should be relatively safe to humans. Most health problems caused by pesticides are due to mis-use, abuse or over-use.
The benefits & risks of pesticides
We know that pesticides kill bugs. However, would they be harmful to humans or the environment?
Toxicity of pesticides vary. In many countries, pesticides evaluation are required by law or regulations. In this video, Prof. Hou will introduce the basics of health risk assessments of pesticides.