Dermal Bioavailability of Toluene Aged in Soil

Abstract

When organic chemicals age in soil, they can become more sequestered with time and less bioavailable. The impact of aging in soil was assessed on the dermal bioavailability of toluene. Comparisons were made between the dermal bioavailability of toluene aged in two soils (Atsion and Keyport) for 3 months, toluene in freshly spiked soil, and toluene without soil (pure chemical). In vitro flow-through diffusion cell methodology measured the amount of radioactive chemical that penetrated dermatomed male pig skin into receptor fluid, and that was detected in skin following soap and water decontamination. Volatilization reduced the amount of toluene that was available for skin penetration. Therefore, relative to the available dose, the total penetration of pure toluene (sum of the dose in the receptor fluid and skin) was 93%. The majority of pure toluene was found in skin (82%). The dermal bioavailability of non-aged and aged toluene was decreased to 4–6% and 3–4% of the available dose, respectively. The data suggest that there would be a lower potential risk to human health from dermal exposure to toluene in soil. However, lower soil loading and longer aging time are needed to quantitate the risk.

Keywords:

• Volatile organic chemical
• skin penetration
• matrix effects
• risk assessment

Acknowledgment

This research was supported through funding from the Hazardous Substance Management Research Center and the New Jersey Commission on Science and Technology.

Notes

^a Mean ± SEM of μg/cm² for n = 9–13 replicates per treatment from three pigs.

^a Mean ± SEM of (μ g/cm² of initial dose penetrated divided by μ g/cm² of initial dose available for penetration) × 100 for n = 9–13 replicates per treatment from three pigs.

^b Significantly different from pure toluene (p < 0.05, ANOVA).

^c Significantly different from toluene in the corresponding freshly spiked soil (p < 0.05, ANOVA).

^d Significantly different from toluene aged in Atsion soil (p < 0.05, Student's independent t-test).