Atrazine and Simazine: 
Restrictions now effective

The UK ban on atrazine and simazine use in non-agricultural situations came into force on 31 August 1993. From this date, local authorities, railway and road maintenance authorities and other non-agricultural users of herbicides may not use atrazine or simazine even if they have remaining supplies.

The ban was imposed by Ministers on the advice of the  Advisory Committee on Pesticides (ACP) because of the continued detection of the two herbicides in drinking water sources at levels which exceeded the legal limits. In addition to totally banning atrazine and simazine use in non-crop environments, aerial spraying of atrazine and simazine has been banned and doses applied to agricultural land restricted to one application, or its equivalent in a number of reduced doses per year. Home garden use of atrazine and simazine continues to be permitted.

    The government also announced that atrazine and simazine use will be banned on crop land falling within ground water protection zones which might be designated in the future, and users of the herbicides should be advised to plant six metre grass strips around their land to prevent soil run-off carrying residues into water.

Still in use and still in water

A total of 80 products containing atrazine and 101 containing simazine are listed as registered for use in Pesticides 1993, the published list of approved pesticides. In last year’s edition 122 and 117 products containing atrazine and simazine respectively were registered. While home garden use is still permitted, this is a market which only uses very small quantities of pesticides, and an increase in the number of products in this sector does not necessarily imply increased use of chemicals. Ciba Agriculture, a basic manufacturer of atrazine and simazine (as opposed to a formulator) suggests that its atrazine sales in the UK will apparently not be affected by the ban since it is used in maize whose planted area has increased in the UK from 23,000 ha. in 1988 to 50,000 ha. last year. Simazine use is however, expected to decline. Ciba claims to have pre-empted the restrictions on atrazine by recommending reduced applications on its product labels, and is now not replacing products for the amenity market. Many pesticide manufacturers who previously sold formulations containing atrazine and simazine to the amenity sector are now promoting alternative chemicals such as dichlobenil, paraquat, glyphosate and diuron, which has recently also been found in drinking water sources.

    According to the Drinking Water Inspectorate, atrazine and simazine continued to be found in public water supplies throughout 1992, and by their chemical nature are expected to be found in water for some time to come.

Not a risk to human health

In July 1993 the ACP published two further reports on atrazine and simazine documenting the review of data relating to their toxicity to mammals and to the environment. Their conclusion was that the chemicals presented “little risk to terrestrial species except quail chick where some hormonal effects were detected.”

    In fact, throughout the evaluation process, the ACP and the Ministry of Agriculture have made a point of stressing that restrictions imposed on atrazine and simazine are not the result of any health risk, but only to keep residue levels in water within the legally imposed EC limit of 0.1 µg/l for any single pesticide.

    Some evidence of carcinogenicity was found in laboratory tests with both atrazine and simazine, and some evidence of birth defects in rabbits fed relatively high doses of simazine. However, human exposure to the chemicals through food residues or direct exposure of spray operators was deemed by the ACP to be below levels which might cause any toxic effects. Interestingly the reports do not seem to look at consumer exposure via drinking water carrying residues despite their presence in water being the main concern which led to the restrictions on their use. (MD)

Evaluation No.71: Evaluation on atrazine (2), July 1993, MAFF, Pesticides Safety Directorate.

Evaluation No.72: Evaluation on simazine (2), July 1993, MAFF, Pesticides Safety Directorate.

[This article first appeared in Pesticides News No.21,September 1993, page 19]