Tetrabromobisphenol A (TBBPA) is used in a diverse array of products to improve fire safety. The National Toxicology Program (NTP) recently completed a 2-year bioassay for TBBPA. The objective of the present study was to develop a cancer-based and a non-cancer based toxicity value and to compare such to appropriate estimates of human exposure. Data from the NTP 2-year and 13-week studies were selected to develop candidate toxicity values. Benchmark dose modeling and subsequent evaluation of candidate values resulted in selection of an oral reference dose (RfD) of 0.6 mg kg À1 day À1 based on uterine hyperplasia in rats and an oral cancer slope factor (OSF) of 0.00315 per mg kg À1 day À1 based on an increased incidence of uterine tumors in rats. Lifetime average daily dose (LADD) estimates ranged from 2.2 E À7 to 3.9 E À6 mg kg À1 day À1 based on age-adjusted exposures to TBBPA via breast milk consumption, dietary intake, soil/dust ingestion and drinking water ingestion in infants, young children, older children and adults. Average daily dose (ADD) estimates ranged from 3.2 E À7 to 8.4 E À5 mg kg À1 day À1. Resulting margin of exposure (MOE) values were > 800 000 for non-cancer endpoints and > 32 000 000 for cancer-based endpoints. These data collectively indicate a low level of health concern associated with exposures to TBBPA based on current data. It is anticipated that the exposure estimates, along with the toxicity values described within, should be informative for understanding human health hazards associated with TBBPA.

Persistent organic pollutant s ( POP s) are a class of organic compounds that are characterized by their ability to resist degradation through environmental processes, remaining intact for long periods of time. They are semi -volatile and capable of traveling as vapor or being absorbed to particulate matter in environmental media, facilitating long -range transport. Their persistence and mobility have resulted in their ubiquitous presence in the environment, as well as biota, including humans. These chemicals are found even in the most remote areas of the world, such as deserts, open ocean, and the poles, where there is no human activity nor chemical sources, demonstrating their ability to travel such long distances. POPs also are mostly lipophilic, bioaccumulating in fat tissues, and subsequently amplifying in concentration in biota occupying the upper spectrum on the food chain.Common types of POPs include polychlorinated biphenyl s ( PCB s), polychlorinated dibenzo -p -dioxins and furan s ( PCDD/F s), and polybrominated diphenyl ether s ( PBDE s), as well as organochlorine pesticides and fl uorinated compounds. Many are still and/or were intentionally used as pesticides or manufactured for a variety of consumer or industrial applications, whereas others are byproducts of industrial activities. Some examples include DDT, which is still used to control mosquitoes carrying malaria in certain regions of the world, and PCBs, which were used as cooling insulating fl uids for transformers and capacitors as well as paint and cement additives. These chemicals provided benefi cial and economical solutions, and thus were applied in a

No abstract