Evaluation of Pesticide Incident Report 2009-1099

Background

Pest control products are only registered by Health Canada's Pest Management Regulatory Agency (PMRA) for use if there is reasonable certainty that no harm to human health or the environment will result from exposure to, or use of the product as directed on the label. Health Canada collects incident reporting data under the authority of the Pest Control Products Act. If a pesticide manufacturer receives information about an incident involving one of their products, they are required by law to submit that information to Health Canada. Members of the public may also submit information about an incident directly to Health Canada. It is important to note that the information presented in incident reports reflects the observations and opinion of the person reporting it, and does not include any assessment by Health Canada, nor does it confirm an association between the pesticide and the effects reported.

Health Canada considers the reported information to determine if there are potential health or environmental risks associated with a pesticide and, if necessary, takes corrective action. Such action could range from minor label changes to discontinuation of the product.

Incident Report 2009-1099

According to the incident report, 24 crows, 2 starlings and 1 opossum were found dead in Chilliwack, BC.  There were no visible signs of trauma that would indicate that the cause of death for the birds was due to attempted predation; observations regarding the condition of the opossum carcass were not reported.  The carcasses of 16 crows and 2 starlings were submitted to the BC Ministry of Agriculture and Lands Animal Health Centre for post-mortem examination; the dead opossum was not collected.

Exposure of the crows and starlings to methomyl was confirmed by multi-residue pesticides analysis of the stomach contents/lining; no other pesticide residues were detected. Measures of cholinesterase activity in crow and starling brain tissue were consistent with exposure to a carbamate pesticide. The source of methomyl to the birds is unknown.

In accordance with the Pest Control Products Incident Reporting Regulations classification system, this incident was classified as Environment Moderate. This incident report can be requested through the PMRA electronic Public Registry on the Health Canada website.

Health Canada Evaluation

The PMRA reviewed the information submitted for this incident report. Site of application and end-use product information are unknown.  Therefore, the evaluation of the incident was based on the results of a multiresidue tissue analysis, cholinesterase levels, and assessment of the toxicity profile of methomyl. Methomyl is known to be highly acutely toxic to birds. Multi residue pesticide analysis showed that methomyl was the only pesticide detected in crow and starling stomach contents/lining, and measure of cholinesterase in brain tissue were consistent with exposure to a carbamate pesticide. Residue analysis and/or cholinesterase activity were not measured in the opossum, and therefore, exposure cannot be confirmed.

Health Canada Conclusion

Based on the toxicity profile of methomyl, residues found in the dead birds, and brain cholinesterase levels consistent with exposure to a carbamate pesticide, it is highly probable that exposure to methomyl caused the bird mortality.

It is possible that the death of the opossum was the result of methomyl poisoning since methomyl is toxic to mammals, and the opossum was found dead in the vicinity of the crows and starlings which contained methomyl residues and exhibited cholinesterase activity consistent with exposure. 

The PMRA has evaluated this incident and concluded that no regulatory action is required by Health Canada at this time.  The PMRA is currently re-evaluating methomyl, and this information will be taken into consideration in the environmental review.  The causality of this incident was assessed based on information present at the time of the review. Any additional information that may be provided to the PMRA will be taken into consideration, and may change the conclusions.

More information about the Pesticide Incident Reporting Program is available on the Health Canada Web site. Should you require further information please contact the Pesticide Incident Reporting Program.