Swimming emissions from dogs treated with spot-on fipronil or imidacloprid: Assessing the environmental risk.

BACKGROUND

Fipronil and imidacloprid are increasingly recognised as contaminants of concern in aquatic environments. This study aimed to quantify swimming emissions from dogs treated with spot-on fipronil or imidacloprid, assess the associated environmental risks and evaluate whether current label instructions on swimming restrictions are adequate.

METHODS

Emissions from swimming were measured for 49 dogs treated with spot-on fipronil or imidacloprid on days 5, 14 or 28 post-application. The environmental risk was assessed by calculating risk quotients, dividing the predicted environmental concentrations by the predicted no-effect concentrations for freshwater ecosystems.

RESULTS

Mean washoff ranged from 4% to 0.4% of the applied dose for fipronil and 10% to 1.4% for imidacloprid across the 5-28-day period. Risk quotients indicate a risk to aquatic ecosystems throughout the products' duration of action.

LIMITATIONS

The results may underestimate emissions for fipronil, as swimming is permitted from 3 days post-application and measurements began on day 5.

CONCLUSION

This study highlights clear ecological risks from spot-on parasiticides and provides evidence that current label instructions on swimming do not provide sufficient environmental protection. Risk-based parasite control strategies and extended swimming restrictions are recommended. Regulatory review of environmental risk assessments and mitigation measures is warranted to protect aquatic environments.