In 1995 the US EPA and the
manufacturers DuPont agreed to phase out the herbicide cyanazine over a
four year period because of possible human carcinogenicity. EPA also
proposed to cancel most uses of the OP dichlorvos because of a risk of
cancer from dietary exposure. The Pesticides Trust [now PAN UK] wrote to the UK
Advisory Committee on Pesticides for their views on those pesticides in
the UK. The following is a summary of the reply.
Cyanazine
Firstly cyanazine will be reviewed as part of
the EC review programme ‘in the not too distant future’, and for the
reasons that follow, real issues of human or environmental safety do not
seem to be involved. Cyanazine is not widely used in the UK. Secondly,
EPA display a ‘low level of concern’—the period from beginning to
phase out production to the final phase out of use is seven years in
total. And thirdly, the ACP has recently reviewed the compounds atrazine
and simazine, and takes the view that they are similar compounds and no
safety concerns were evident in their cases. Both compounds caused
tumours in rats, but ACP concluded that the rat strain used was
predisposed to develop the mammary tumours observed. A hormonal
mechanism that might have accounted for the tumours in rats was not
relevant for humans, and overall the increased levels of tumours were of
questionable significance for humans and did not indicate an
unacceptable risk.
Dichlorvos
Most uses of dichlorvos are non-agricultural
in the UK. The ACP reviewed non-agricultural uses and concluded that
dichlorvos was not carcinogenic in the rat and the weight of evidence
suggested it did not present a carcinogenic risk to humans or a risk to
fertility or reproduction. Agricultural uses will fall to be reviewed by
the EC in due course.
[This article first appeared in Pesticides News No. 32, June 1996, page 22]