Development of a multi-VOC reference material for quality assurance in materials emission testing.

Emission test chamber measurement is necessary to proof building materials as sources of volatile organic compounds (VOCs). The results of such measurements are used to evaluate materials and label them according to their potential to emit harmful substances, polluting indoor air. If only labelled materials were installed indoors, this would improve indoor air quality and prevent negative impacts on human health. Because of the complex testing procedure, reference materials for the quality assurance are mandatory. Currently, there is a lack of such materials because most building products show a broad variation of emissions even within one batch. A previous study indicates lacquers, mixed with volatile organic pollutants, as reproducible emission source for a wide range of substances. In the present study, the curing of the lacquer-VOC mixture inside micro-chambers was optimised. Therefore, the humidity and the chamber flow were varied. Typical indoor air pollutants with a wide range of volatilities, for example, styrene, n-hexadecane, dimethyl and dibutyl phthalate were selected. It turned out that, under optimised curing parameters inside the micro-chamber, their emission can be reproduced with variations of less than 10 %. With this, a next important step towards a reference material for emission testing was achieved.

Assessing the impact of the duration and intensity of inhalation exposure on the magnitude of the variability of internal dose metrics in children and adults.

The objective of this study was to assess the impact of the exposure duration and intensity on the human kinetic adjustment factor (HKAF). A physiologically based pharmacokinetic model was used to compute target dose metrics (i.e. maximum blood concentration (C(max)) and amount metabolized/L liver/24 h (Amet)) in adults, neonates (0-30 days), toddlers (1-3 years), and pregnant women following inhalation exposure to benzene, styrene, 1,1,1-trichloroethane and 1,4-dioxane. Exposure scenarios simulated involved various concentrations based on the chemical's reference concentration (low) and six of U.S. EPA's Acute Exposure Guideline Levels (AEGLs) (high), for durations of 10 min, 60 min, 8 h, and 24 h, as well as at steady-state. Distributions for body weight (BW), height (H), and hepatic CYP2E1 content were obtained from the literature or from P3M software, whereas blood flows and tissue volumes were calculated from BW and H. The HKAF was computed based on distributions of dose metrics obtained by Monte Carlo simulations [95th percentile in each subpopulation/median in adults]. At low levels of exposure, ranges of C(max)-based HKAF were 1-6.8 depending on the chemical, with 1,4-dioxane exhibiting the greatest values. At high levels of exposure, this range was 1.1-5.2, with styrene exhibiting the greatest value. Neonates were always the most sensitive subpopulation based on C(max), and pregnant women were most sensitive based on Amet in the majority of the cases (1.3-2.1). These results have shown that the chemical-specific HKAF varies as a function of exposure duration and intensity of inhalation exposures, and sometimes exceeds the default value used in risk assessments.