Estimation of absorption of aromatic hydrocarbons diffusing from interior materials in automobile cabins by inhalation toxicokinetic analysis in rats

Abstract

Aromatic hydrocarbons, as well as aliphatic hydrocarbons, diffusing from interior materials in automotive cabins are the most common compounds contributing to interior air pollution. In this study, the amounts of seven selected aromatic hydrocarbons absorbed by a car driver were estimated by evaluating their inhalation toxicokinetics in rats. Measured amounts of these substances were injected into a closed chamber system containing a rat, and the concentration changes in the chamber were examined. The toxicokinetics of the substances were evaluated on the basis of the concentration-time course using a nonlinear compartment model. The amounts absorbed in humans at actual concentrations in automobile cabins without ventilation were extrapolated from the results obtained from rats. The absorbed amounts estimated for a driver during a 2 h drive were as follows (per 60 kg of human body weight): 30 microg for toluene (interior median concentration, 40 microg m(-3) in our previous study), 10 microg for ethylbenzene (12 microg m(-3)), 6 microg for o-xylene (10 microg m(-3)), 8 microg for m-xylene (11 microg m(-3)), 9 microg for p-xylene (11 microg m(-3)), 11 microg for styrene (11 microg m(-3)) and 27 microg for 1,2,4-trimethylbenzene (24 microg m(-3)). Similarly, in a cabin where air pollution was marked, the absorbed amount of styrene (654 microg for 2 h in a cabin with an interior maximum concentration of 675 microg m(-3)) was estimated to be much higher than those of other substances. This amount (654 microg) was approximately 1.5 times the tolerable daily intake of styrene (7.7 microg kg(-1) per day) recommended by the World Health Organization.

Volatile organic compounds in ventilated critical care patients: a systematic evaluation of cofactors

“…Therefore, 2-methylpentane might also be released by the ventilator. Yoshida demonstrated the pulmonary absorption of 2-methylpentane by inhalation in a rat model based on the knowledge of well-known diffusion [ 37 ]. To what extent inhaled 2-methylpentane affects concentrations in expired air also remains unknown.…”

Car indoor air pollution - analysis of potential sources

“…Next to particulate matter, other noxious compounds including aromatic hydrocarbons, as well as aliphatic hydrocarbons, may play a role in indoor air quality. They diffuse from interior materials in car cabins [ 14 ]. In a recent study, seven selected aromatic hydrocarbons were assessed concerning their inhalation toxicokinetics in rats.…”

“…In brief, amounts of these substances were injected into a closed chamber system containing one rat, and concentration changes in the chamber were examined. Afterwards, toxicokinetics of the substances were analysed on the basis of the concentration-time course using a nonlinear compartment model [ 14 ]. Furthermore, the amounts absorbed in humans at actual concentrations in car cabins without ventilation were extrapolated from the results obtained from rats.…”

“…In specific, the absorbed amounts estimated for a driver during a 2 h drive were as follows per 60 kg of human body weight: 30 μg for toluene, 10 μg for ethylbenzene, 6 μg for o-xylene, 8 μg for m-xylene, 9 μg for p-xylene, 11 μg for styrene and 27 μg for 1,2,4-trimethylbenzene. Concomitantly, in a cabin in which air pollution was marked, the absorbed amount of styrene (654 μg for 2 h in a cabin with an interior maximum concentration of 675 μg/m3) was estimated to be significantly higher than those of other substances [ 14 ]. This amount (654 μg) was approximately 1.5 times the tolerable daily intake of styrene (7.7 μg/kg per day) recommended by the World Health Organization [ 14 ].…”

“…Concomitantly, in a cabin in which air pollution was marked, the absorbed amount of styrene (654 μg for 2 h in a cabin with an interior maximum concentration of 675 μg/m3) was estimated to be significantly higher than those of other substances [ 14 ]. This amount (654 μg) was approximately 1.5 times the tolerable daily intake of styrene (7.7 μg/kg per day) recommended by the World Health Organization [ 14 ].…”