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Polybrominated diphenyl ether (PBDE) body burdens in North America are 20 times that of Europeans and some "high accumulation" individuals have burdens up to 1-2 orders of magnitude higher than median values, the reasons for which are not known. We estimated emissions and fate of sigma PBDEs (minus BDE-209) in a 470 km2 area of Toronto, Canada, using the Multi-media Urban Model (MUM-Fate). Using a combination of measured and modeled concentrations for indoor and outdoor air, soil, and dust plus measured concentrations in food, we estimated exposure to sigma PBDEs via soil, dust, and dietary ingestion and indoor and outdoor inhalation pathways. Fate calculations indicate that 57-85% of PBDE emissions to the outdoor environment originate from within Toronto and that the dominant removal process is advection by air to downwind locations. Inadvertent ingestion of house dust is the largest contributor to exposure of toddlers through to adults and is thus the main exposure pathway for all life stages other than the infant, including the nursing mother, who transfers PBDEs to her infant via human milk. The next major exposure pathway is dietary ingestion of animal and dairy products. Infant consumption of human milk is the largest contributor to lifetime exposure. Inadvertent ingestion of dust is the main exposure pathway for a scenario of occupational exposure in a computer recycling facility and a fish eater. Ingestion of dust can lead to almost 100-fold higher exposure than "average" for a toddler with a high dust intake rate living in a home in which PBDE concentrations are elevated.

We submit that the safe operating space of the planetary boundary of novel entities is exceeded since annual production and releases are increasing at a pace that outstrips the global capacity for assessment and monitoring. The novel entities boundary in the planetary boundaries framework refers to entities that are novel in a geological sense and that could have large-scale impacts that threaten the integrity of Earth system processes. We review the scientific literature relevant to quantifying the boundary for novel entities and highlight plastic pollution as a particular aspect of high concern. An impact pathway from production of novel entities to impacts on Earth system processes is presented. We define and apply three criteria for assessment of the suitability of control variables for the boundary: feasibility, relevance, and comprehensiveness. We propose several complementary control variables to capture the complexity of this boundary, while acknowledging major data limitations. We conclude that humanity is currently operating outside the planetary boundary based on the weight-of-evidence for several of these control variables. The increasing rate of production and releases of larger volumes and higher numbers of novel entities with diverse risk potentials exceed societies’ ability to conduct safety related assessments and monitoring. We recommend taking urgent action to reduce the harm associated with exceeding the boundary by reducing the production and releases of novel entities, noting that even so, the persistence of many novel entities and/or their associated effects will continue to pose a threat.