Pesticides - friend or foe?

Abstract

Pesticides, where used correctly, can save up to 40% in crop losses; however, when pesticides are mal-, mis-or over-used the environmental and public health consequences can be very considerable. The United Nations has issued a list of chemicals that are banned or severely restricted in use; many of the chemicals on this list are pesticides. Whilst the use of highly persistent pesticides such as DDT has proved very effective in the eradication of diseases such as malaria, the adverse effects to the natural environment have been devastating - whole populations of birds have been eliminated. Within the former Soviet Union, the use of highly persistent pesticides was widespread; this has resulted in contamination of both crops, with pesticide residues well in excess of internationally acceptable maximum residue limits, and water resources to such high level that remediation through natural processes will take decades, or by xenobiotic or physicochemical processes will be extremely costly. This is an extraordinary situation as the former Soviet Union had one of the most stringent of environmental regulation - the GOST regulations; unfortunately these were not pragmatic and rarely applied. When in the Ukraine in 1994, I heard that farmers where paid for every application made; the result was crops, soil, water and the environment were highly contaminated, and in some cases the land became barren. Currently, the situation in some countries is that no pesticides are being applied because under the new market conditions farmers cannot afford to purchase pesticides. In Armenia in July 1995, one could not purchase fruit which was not diseased. The effects of mis-use of pesticides are known to cause very serious adverse effects to human health: in some countries children are exhibiting excessive cancer incidences; crops found to be highly contaminated with up to five different pesticides are being condemned, often being burnt in the fields. As these crops in all probability contained now banned and highly persistent pesticides, mere burning at low temperatures is producing even more toxic dioxins, furans, etc. This leads to both air and soil contamination. One answer would be for the farmer to be obliged to pay for high-temperature incineration in a high-tech incinerator in a developed country, which, subject to prior informed consent, could cost US $5000/tonne. However, the application of modern pesticides in accordance with manufacturers' specifications can incur none of these problems; this presentation will outline how pesticides can be used judiciously.