Chemical Safety is achieved by undertaking all activities involving chemicals in such a way as to ensure the safety of human health and the environment. It covers all chemicals, natural and manufactured, and the full range of exposure situations from the natural presence of chemicals in the environment to their extraction or synthesis, industrial production, transport use and disposal.
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Chemical safety has many scientific and technical components. Among these are toxicology, ecotoxicology and the process of chemical risk assessment which requires a detailed knowledge of exposure and of biological effects.
Through the International Programme on Chemical Safety (IPCS), WHO works to establish the scientific basis for the sound management of chemicals, and to strengthen national capabilities and capacities for chemical safety.
There are more than 1000 pesticides used around the world to ensure food is not damaged or destroyed by pests. Each pesticide has different properties and toxicological effects.
Many of the older, cheaper (off-patent) pesticides, such as dichlorodiphenyltrichloroethane (DDT) and lindane, can remain for years in soil and water. These chemicals have been banned by countries who signed the 2001 Stockholm Convention – an international treaty that aims to eliminate or restrict the production and use of persistent organic pollutants.
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The toxicity of a pesticide depends on its function and other factors. For example, insecticides tend to be more toxic to humans than herbicides. The same chemical can have different effects at different doses (how much of the chemical a person is exposed to). It can also depend on the route by which the exposure occurs (such as swallowing, inhaling, or direct contact with the skin).
None of the pesticides that are authorized for use on food in international trade today are genotoxic (damaging to DNA, which can cause mutations or cancer). Adverse effects from these pesticides occur only above a certain safe level of exposure. When people come into contact with large quantities of pesticide, this may cause acute poisoning or long-term health effects, including cancer and adverse effects on reproduction.
Scope of the problem
Pesticides are among the leading causes of death by self-poisoning, in particular in low- and middle-income countries.
As they are intrinsically toxic and deliberately spread in the environment, the production, distribution, and use of pesticides require strict regulation and control. Regular monitoring of residues in food and the environment is also required.
WHO has two objectives in relation to pesticides:
- to ban pesticides that are most toxic to humans, as well as pesticides that remain for the longest time in the environment.
- to protect public health by setting maximum limits for pesticide residues in food and water.
Who is at risk?
The most at-risk population are people who are directly exposed to pesticides. This includes agricultural workers who apply pesticides, and other people in the immediate area during and right after pesticides are spread.
The general population – who are not in the area where pesticides are used – is exposed to significantly lower levels of pesticide residues through food and water.
Prevention and control
Nobody should be exposed to unsafe amounts of pesticide.
People spreading pesticide on crops, in homes, or in gardens should be adequately protected. People not directly involved in the spread of pesticides should stay away from the area during and just after a spread.
Food that is sold or donated (such as food aid) should comply with pesticide regulations, in particular with maximum residue limits. People who grow their own food should, when using pesticides, follow instructions for use and protect themselves by wearing gloves and face masks as necessary.
Consumers can further limit their intake of pesticide residues by peeling or washing fruit and vegetables, which also reduces other foodborne hazards, such as harmful bacteria.