The importance of variations in in vitro dosimetry to support risk assessment of inhaled toxicants

Abstract

disinfectant or preservative in funeral homes and medical labs), or via indoor air (e.g., resulting from combustion processes such as heating, cooking, or tobacco smoke, or emanating from building materials).The assessment of human health risks from the possible variations in inhalation exposures can be challenging when based on in vivo toxicity data. Such data are often limited to information from an animal experiment with a standard exposure regimen such as 6 h/day for 5 days per week over 28 days or 90 days as prescribed in OECD Test Guidelines 412 and 413, respectively. If epidemiological data are available, the exposure generally is expressed as a rough estimate, i.e., as ppm-years, or as an inhaled average daily IntroductionReal-life inhalation exposures are dynamic and may vary from a brief peak exposure of a few minutes to a continuous 24/7 exposure from environmental air. Exposures may be daily, once a week or less frequent. Exposures include single daily peak exposures (e.g., during use of a spray such as a deodorant) or multiple daily peak exposures such as vaping or smoking tobacco cigarettes. In addition, sources of exposure to a chemical may vary, leading to several possible exposure scenarios for one chemical or particle. For example, exposure to formaldehyde may be occupational (production and occupational use as, e.g., an industrial