WHAT WE KNOW ABOUT PESTICIDE RESIDUES IN FOODPesticides are used to selectively control a variety of biological pests such as insects, weeds, rodents and moulds. Although they are not meant for human consumption, their pattern of use and distribution in the environment means they find their way into food and water. The main pesticides of concern are the organochlorines such as DDT, dieldrin, and lindane (because of their extreme persistence and accumulation in the environment and food) and the organophosphorus compounds such as malathion and parathion (because of their high toxicity).
Health authorities have established maximum limits on the level of individual pesticide
residues in the diet that are considered to be safe for the general population. These limits
take account of the joint need to provide an adequate, economical and wholesome food
supply. The health risk to the consumer from trace levels of pesticides in the diet is small.
Even if an occasional food is in excess of the acceptable limit, there is a sufficient built-in
margin of safety to ensure that there is still little likelihood that it will pose a threat to
health. It must be recognised that some older pesticides when re-evaluated using
contemporary safety standards may be identified as potentially carcinogenic or in some
other way hazardous to humans or the environment and that prompt action by regulatory
bodies to reduce such risks needs to be taken.
Australia has been monitoring pesticide residues in food since 1970. When pesticides are
used in the manner and quantities recommended on their labels, any residues should be
within acceptable health limits. However, crude 'bucket and shovel' methods, inappropriate
application rates and shortening of withholding periods can result in unacceptably high
residues in food. A thorough program of monitoring is essential if such foods are to be
detected. Since monitoring began, developments in analytical chemistry have resulted in the
detection of residues in ever decreasing amounts. Residues once not detectable are now
being found using newer, more sensitive analytical methods. However, the ability to detect
these minute amounts has outstripped the ability of toxicologists to predict the health
significance of such low levels of exposure.
There may be some people in the community who are sensitive to a pesticide or who are exposed to higher amounts because they have unusual diets or consume large amounts of particular foods. It would be prudent for such people to minimise exposure by washing fruits and vegetables or removing peel, outer leaves or excess fat before consumption. Cooking may lower the pesticide load even further. Where food is produced in home gardens using pesticides, it is important that all instructions on their use be followed, particularly the time between its application and harvesting in order that any residue is minimised.