Evaluation of Pesticide Incident Report 2011-2674

This content was archived on June 24, 2013.

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 2011-2674

A report was received by the PMRA for an incident that occurred on May 25, 2011, involving the death of farmed Atlantic salmon (Salmo salar) that were treated in a well boat with Interox-Paramove 50 (PCP Registration Number 29783), which contains 50% of the active ingredient hydrogen peroxide. The incident occurred on Grand Manan Island, New Brunswick.

The incident report indicates that of 34,625 fish that were treated, several fish exhibited abnormal bevahiour, 4,984 fish were immediately harvested post treatment and 9,000 dead fish were removed from the cage the following day.

According to the incident report, the water discharge screen aboard the well boat became plugged with kelp and other seaweed when flushing was attempted. This resulted in delayed flushing of the hydrogen peroxide from the well and an extended exposure time of the fish to hydrogen peroxide.

In accordance with the Pest Control Products Incident Reporting Regulations classification system, this incident was classified as Domestic Animal Death. This incident report is available through the PMRA electronic Public Registry on the Health Canada Web site.

Health Canada Evaluation

In New Brunswick, Nova Scotia and Newfoundland, Interox-Paramove 50 was granted a one year emergency registration for the control of sea lice in farmed Atlantic salmon residing in contained well boats. Non-target wild fish were not harmed during the treatment. The PMRA assessment is based on effects to the Atlantic salmon host crop.

When used according to label directions, Interox-Paramove 50 is not known to cause mortality to the farmed Atlantic salmon host crop. Based on the information provided for this incident, the product was applied according to label directions. However, due to a technical complication during the chemical flushing process of the exposure tank, the target host crop was exposed to Interox-Paramove 50 for a period of time which exceeded the exposure time under the directions for use on the product label. The abnormally high number of fish that died was expected given the application rate, the exposure time and the concentrations of hydrogen peroxide known to result in fish mortality. Interox-Paramove 50 has been used in New Brunswick under the emergency registration in many other instances according to the directions on the product label without abnormally high fish mortality.

Health Canada Conclusion

Based on the measured concentration, prolonged treatment duration, the high percentage of reported mortality and the toxicity profile of hydrogen peroxide to the Atlantic salmon host crop, the PMRA concluded that it is highly probable that exposure to hydrogen peroxide caused the Atlantic salmon host crop mortality.

The causality of this incident was assessed based on evaluated information present at the time of the review. The PMRA has concluded that no additional regulatory action is required by Health Canada at this time. Consideration was given to the fact that this incident was caused by a temporary equipment malfunction which resulted in prolonged exposure time, and that hydrogen peroxide has been used successfully in numerous treatments without resulting in high numbers of fish deaths. It should be noted that any additional information regarding this incident that is provided to the PMRA will be taken into consideration and may change this conclusion.

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.