Remediating Indoor Pesticide Contamination from Improper Pest Control Treatments: Persistence and Decontamination Studies

The improper and excessive use of pesticides in indoor environments can result in adverse human health effects, sometimes necessitating decontamination of residential or commercial buildings. A lack of information on effective approaches to remediate pesticide residues prompted the decontamination and persistence studies described in this study. Decontamination studies evaluated the effectiveness of liquid-based surface decontaminants against pesticides on indoor surfaces. Building materials were contaminated with 25-2,400 mu g/100cm(2) of the pesticides malathion, carbaryl, fipronil, deltamethrin, and permethrin. Decontaminants included both off-the-shelf and specialized solutions representing various chemistries. Pesticides included in this study were found to be highly persistent in a dark indoor environment with surface concentrations virtually unchanged after 140 days. Indoor light conditions degraded some of the pesticides, but estimated half-lives exceeded the study period. Decontamination efficacy results indicated that the application of household bleach or a hydrogen peroxide-based decontaminant offered the highest efficacy, reducing malathion, fipronil, and deltamethrin by > 94-99% on some surfaces. Bleach effectively degraded permethrin ( > 94%), but not carbaryl ( < 70%) while the hydrogen peroxide containing products degraded carbaryl (>71-99%) but not permethrin (<54%). These results will inform responders, the general public and public health officials on potential decontamination solutions to remediate indoor surfaces.