Variability of pyrethroid concentrations on hard surface kitchen flooring in occupied housing

Area of Science:

• Environmental Chemistry
• Toxicology
• Occupational Health

Background:

• Pyrethroids are widely used neurotoxic insecticides with potential human exposure routes in homes.
• Estimating indoor pyrethroid concentrations often relies on wipe sampling, but temporal variability is poorly understood.
• Accurate exposure assessment requires understanding how pesticide concentrations change over time due to human activities.

Purpose of the Study:

• To assess the temporal variability of eight pyrethroids and six degradation products in occupied housing.
• To determine the minimum number of wipe samples needed for reliable estimation of indoor pyrethroid concentrations.

Main Methods:

• Collected two hard surface kitchen floor wipe samples from 50 occupied residences across three time points over six weeks.
• Participants maintained pesticide use diaries for one month prior to and during sample collection.
• Analyzed samples for eight pyrethroids and six pyrethroid degradation products.

Main Results:

• Pyrethroids were commonly detected and frequently co-occurred in the studied residences.
• Pesticide applications, though not directly correlated with detection frequencies, were linked to concentration changes.
• Degradation products were generally found at lower concentrations and less frequently than parent pyrethroids.
• Intraclass correlation coefficients (ICC) for pyrethroids ranged from 0.55 to 0.80.
• Two sampling events per residence were sufficient to achieve an ICC of 0.80 for most pyrethroids.

Conclusions:

• Indoor pyrethroid concentrations exhibit temporal variability influenced by pesticide applications.
• A reduced sampling strategy (two events) can provide reliable estimates of mean pyrethroid concentrations in homes.
• Findings inform more accurate indoor pesticide exposure assessments and risk evaluations.