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Sergeant Phil Cannings, Wildlife Officer with poisoned red kite – a rare bird of prey. During 1998 there were 10 confirmed
pesticide poisonings of these birds, of which four involved the abuse of agricultural chemicals.
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Metaldehyde slug pellets have killed another twelve dogs, five cats and an unknown number of wild mammals and birds, but, according to a senior MAFF scientist, approval for the pesticide is unlikely to be revoked. ‘It can’t be’, says Dr Mark Fletcher, of the Central Science Laboratory, and one of the authors of this year’s Wildlife Incident Investigation Scheme report. ‘Since the burning of straw was prohibited there have been a lot of slugs around. Farmers have no choice but to use slug pellets, and methiocarb is more toxic than metaldehyde’.
Metaldehyde is second only to carbofuran, a carbamate, as a cause of death to non-target animals – it is implicated in 26 confirmed incidents – and it could be killing numerous wild birds and mammals whose carcases are never found.
This year’s report concludes that ‘agricultural chemicals, if used in an approved manner, are apparently not causing major problems to wildlife and other animals’. It does acknowledge, however, that wild animals ‘are likely to skulk in cover once affected, unlike dogs that are in close proximity to humans’.
‘Wild animals like badgers and foxes often go underground to die’, says Dr Fletcher. ‘There may be more problems with the approved use of metaldehyde, but we never see them.’
Part-funded by a levy on the agrochemical industry, the Scheme is designed to provide a system of post-registration product surveillance: data from it is supplied to the Advisory Committee on Pesticides (ACP) so that the risks of a product can be re-evaluated if necessary, and changes made to its status or approval conditions.
But, if metaldehyde is anything to go by, institutional acceptance of the toxic costs of pesticides is all too clear. The ACP stated, in its review of the compound in 1996 that metaldehyde poses risks to small mammals and birds, and to companion animals from misuse. It recommended that manufacturers should:
Supply the product for garden use in containers designed so that no skin contact is necessary
Include a repellent, so as to reduce palatability to dogs
Improve labelling
The ACP also required the Wildlife Incident Information Scheme (WIIS) to gather the following information when incidents involved metaldehyde poisoning of companion animals:
Full details of the animal involved and its feed
Full details of the product implicated
Analysis of the repellent content
But the latter recommendation, crucially, has not been carried out. ‘We haven’t done it’, says Dr Fletcher. ‘We don’t have a method for detecting repellent’.
A further aim of the Scheme, to provide evidence for use in prosecutions under pesticide control legislation, seems unfulfilled. In 1998, of 14 incidents of suspected pesticide abuse investigated so far by MAFF, no prosecutions have ensued.
Instances of ‘misuse’ have risen sharply this year: 26% of incidents, compared with only 12% in 1997. ‘Misuse’ is defined as ‘careless, accidental or wilful failure to adhere to the correct practice’, for example, when a user spills the product, or does not store it properly.
But to include the accidental consequences of using pesticides in ‘misuse’ is prejudicial. The most scrupulous user who follows instructions precisely can still have accidents. For example, in one of the metaldehyde incidents, slug pellets fell off equipment when it was turned round. Only 10 of the 26 incidents involving metaldehyde are confirmed as ‘abuse’, in which the product has been illegally used with the intention of killing animals.
Twice as many incidents are confirmed as having been caused by pesticides by the WIIS than by the equivalent scheme for humans, run by the Health & Safety Executive’s Pesticide Incident Appraisal Panel report. So why are laboratory analyses not used more effectively in cases of human exposure?
‘We can confirm more incidents because we have dead animals to examine and the chemical analyses’, says Denise Lamb of the Pesticides Safety Directorate. ‘With people, you’re just trying to get them better. Very few tests have been developed to test for pesticides in people and in most cases they’re unnecessary.’
Omission of unconfirmed and negative data will distort any overall picture. The WIIS tends to accept only ‘likely’ cases, arguing that their resources are limited. And a current PSD review of the criteria for acceptance of incidents is likely to make their inclusion even more difficult.
Currently, incidents will only be accepted if there is strong evidence that a pesticide has been involved, so, for example, carcases found near a road or telegraph wire will be rejected. This could mean that badgers illegally poisoned and dumped on a road would not be included. The WIIS will prioritise species of conservation interest, such as birds of prey, and carcases found in sensitive areas, such as the red kite re-release areas. Any reports must be discussed by the Farming and Rural Conservation Agency officer with colleagues, and cases where there is already a history of poisonings, or rumours of it, will be considered. If a veterinary opinion, or diagnosis, or post-mortem, is available, or where there is information from other organisations such as the police or RSPCA, carcases will be accepted.
A key statistic is missing from the WIIS reports: how many incidents are reported to them in the first place? Whereas in the PIAP report it is possible to calculate how many cases have been rejected, WIIS does not include the carcases reported to the ‘hotline’ telephone number. This figure would provide a benchmark against which problems of bias within the criteria could be detected and corrected. It might also reveal a considerably higher number of possibly pesticide-related deaths to wild animals than is given here.
(AC)
Dr Mark Fletcher, E A Barnett (Central Science Laboratory, MAFF, York), and K Hunter and E A Sharp (Scottish Office Agriculture, Environment and Fisheries Department), Pesticide Poisoning of Animals 1998, published 2000, 54pp.
[This article first appeared in Pesticides News No. 48, June 2000, page 14]