Human exposure to indoor residential cyfluthrin residues during a structured activity program

Area of Science:

• Environmental Science
• Toxicology
• Occupational Health

Background:

• Accurate estimation of absorbed daily dosage (ADD) is crucial for chemical risk assessment.
• Biomonitoring offers a more reliable method for ADD assessment compared to environmental measurements, requiring fewer assumptions.
• Cyfluthrin is a common insecticide used in various settings.

Purpose of the Study:

• To compare ADD estimations derived from biomonitoring (urinary excretion) with those predicted from environmental residue measurements.
• To quantify cyfluthrin exposure and its elimination kinetics following contact with treated surfaces.

Main Methods:

• Participants engaged in a structured activity program (SAP) on a carpet treated with Tempo((R)) 20 WP (cyfluthrin).
• Total and transferable cyfluthrin residues were measured on carpet, cotton cloths, socks, and shorts.
• Urinary samples were collected over 72 hours post-SAP and analyzed for the biomarker 4-fluoro-3-phenoxybenzoic acid (FPBA).

Main Results:

• Total carpet residue was 11.1 ± 2.7 µg/cm², while transferable residue on cotton cloth was 0.11 µg/cm².
• Cyfluthrin residues on socks and shorts were 0.74 ± 0.23 µg/cm² and 0.15 ± 0.03 µg/cm², respectively.
• Mean excreted cyfluthrin equivalents were 8.4 ± 5.7 µg/person, resulting in an ADD of 0.10 µg/kg with an elimination half-life of 16 ± 5 hours.

Conclusions:

• Biomonitoring via urinary FPBA excretion provided a more accurate measure of absorbed cyfluthrin dosage.
• Environmental residue measurements significantly overestimated the actual absorbed daily dosage (ADD).
• This study highlights the importance of biomonitoring for precise human exposure assessments in risk management.