Are There Other Persistent Organic Pollutants? A Challenge for Environmental Chemists

Abstract

The past 5 years have seen some major successes in terms of global measurement and regulation of persistent, bioaccumulative, and toxic (PB&T) chemicals and persistent organic pollutants (POPs). The Stockholm Convention, a global agreement on POPs, came into force in 2004. There has been a major expansion of measurements and risk assessments of new chemical contaminants in the global environment, particularly brominated diphenyl ethers and perfluorinated alkyl acids. However, the list of chemicals measured represents only a small fraction of the approximately 30,000 chemicals widely used in commerce (>1 t/y). The vast majority of existing and new chemical substances in commerce are not monitored in environmental media. Assessment and screening of thousands of existing chemicals in commerce in the United States, Europe, and Canada have yielded lists of potentially persistent and bioaccumulative chemicals. Here we review recent screening and categorization studies of chemicals in commerce and address the question of whether there is now sufficient information to permit a broader array of chemicals to be determined in environmental matrices. For example, Environment Canada's recent categorization of the Domestic (existing) Substances list, using a wide array of quantitative structure activity relationships for PB&T characteristics, has identified about 5.5% of 11,317 substances as meeting P & B criteria. Using data from the Environment Canada categorization, we have listed, for discussion purposes, 30 chemicals with high predicted bioconcentration and low rate of biodegradation and 28 with long range atmospheric transport potential based on predicted atmospheric oxidation half-lives >2 days and log air-water partition coefficients > or =5 and < or =1. These chemicals are a diverse group including halogenated organics, cyclic siloxanes, and substituted aromatics. Some of these chemicals and their transformation products may be candidates for future environmental monitoring. However, to improve these predictions data on emissions from end use are needed to refine environmental fate predictions, and analytical methods may need to be developed.

Brominated Flame Retardants

“…Overall, concentrations of BFRs measured to date in the Arctic are very low compared to those of 'legacy' POPs. There are a number of semi-volatile BFRs which, due to their relatively long predicted atmospheric half-lives, could undergo airborne transport and which therefore represent good candidates for future surveys of spatial and temporal trends, both in the Arctic and elsewhere (Muir and Howard, 2006). For discussion purposes, Muir and Howard list 30 chemicals with high predicted bioconcentration and a low rate of biodegradation and 28 with long-range atmospheric transport potential.…”

Spatial differentiation of chemical removal rates from air in life cycle impact assessment

“…Persistence (P), long-range transport potential (LRTP), bioaccumulation (B), and toxicity (T) are characteristics directly related to a chemical's environmental risk (Muir and Howard 2006). Since these characteristics are related to physicalchemical properties, organic chemicals were clustered on the basis of their physical-chemical properties in order to define a general framework for identifying groups of chemicals with likely similar fate behavior in the environment.…”

A New Glider-Compatible Optical Sensor for Dissolved Organic Matter Measurements: Test Case from the NW Mediterranean Sea

“…As a result of urban, industrial, agriculture and maritime activities, a great diversity of organic pollutants are continuously introduced in the marine environment. These pollutants fuel DOM pools and impact ecosystem functioning and biogeochemical cycles (Muir and Howard, 2006;Dachs and Méjanelle, 2010;Tornero and Hanke, 2016). Although their fate is unclear, the role of these pollutants is likely significant for the oceanic carbon cycle (González-Gaya et al, 2016).…”