The U.S. Environmental Protection Agency (EPA) is faced with the challenge of efficiently and credibly evaluating chemical safety often with limited or no available toxicity data. The expanding number of chemicals found in commerce and the environment, coupled with time and resource requirements for traditional toxicity testing and exposure characterization, continue to underscore the need for new approaches. In 2005, EPA charted a new course to address this challenge by embracing computational toxicology (CompTox) and investing in the technologies and capabilities to push the field forward. The return on this investment has been demonstrated through results and applications across a range of human and environmental health problems, as well as initial application to regulatory decision-making within programs such as the EPA’s Endocrine Disruptor Screening Program. The CompTox initiative at EPA is more than a decade old. This manuscript presents a blueprint to guide the strategic and operational direction over the next 5 years. The primary goal is to obtain broader acceptance of the CompTox approaches for application to higher tier regulatory decisions, such as chemical assessments. To achieve this goal, the blueprint expands and refines the use of high-throughput and computational modeling approaches to transform the components in chemical risk assessment, while systematically addressing key challenges that have hindered progress. In addition, the blueprint outlines additional investments in cross-cutting efforts to characterize uncertainty and variability, develop software and information technology tools, provide outreach and training, and establish scientific confidence for application to different public health and environmental regulatory decisions.

Concern over persistence, bioaccumulation, and toxicity has led to international regulation and phase-outs of certain perfluorinated compounds and little is known about their replacement products. High resolution mass spectrometry was used to investigate the occurrence and identity of replacement fluorinated compounds in surface water and sediment of the Tennessee River near Decatur, Alabama. Analysis of legacy Per- and polyfluoroalkyl substances (PFASs) revealed a marked increase in concentrations downstream of manufacturing facilities, with the most abundant compounds being perfluorooctanesulfonate (PFOS), perfluorobutanesulfonate (PFBS), and perfluorooctanoic acid (PFOA) as high as 220 ng L, 160 ng L, and 120 ng L, respectively. A series of nine polyfluorinated carboxylic acids was discovered, each differing by CFCH. These acids are likely products or byproducts of a manufacturing process that uses 1,1-difluoroethene, which is registered to a manufacturing facility in the area. Two other predominant compounds discovered have structures consistent with perfluorobutanesulfonate and perfluoroheptanoic acid but have a single hydrogen substituted for a fluorine someplace in their structure. A polyfluoroalkyl sulfate with differing mixes of hydrogen and fluorine substitution was also observed. N-methyl perfluorobutane sulfonamidoacetic acid (MeFBSAA) was observed at high concentrations and several other perfluorobutane sulfonamido substances were present as well.

Dust, indoor air, outgoing air from ventilation systems, outdoor air, and soil were sampled in and around Stockholm, Sweden during the winter and spring 2012. The concentrations of several emerging flame retardants (EFRs), polybrominated diphenyl ethers (PBDEs), and isomers of hexabromocyclododecane (HBCDD) were measured. The most commonly found EFR was 1,2-dibromo-4-(1,2 dibromoethyl)cyclohexane (TBECH or DBE-DBCH), which was found in nearly all indoor, ventilation, and outdoor air samples, most dust samples, but not in soil samples. Other frequently detected EFRs included pentabromotoluene (PBT), hexabromobenzene (HBB), 2,3,4,5-tetrabromo-ethylhexylbenzoate (EHTBB), 2,3,4,5-tetrabromo-bis(2-ethylhexyl) phthalate (BEH-TEBP), and decabromodiphenyl ethane (DBDPE). PBDE concentrations were significantly lower in air and dust samples compared to a previous study in Stockholm. In outdoor air, DBE-DBCH, PBT, EHTBB, DBDPE, and PBDEs showed an "urban pulse" with concentrations increasing as samples were taken in more urban areas compared to rural areas. These EFRs show similar environmental behavior as PBDEs. Higher brominated BDEs showed this same urban pulse in soil but lower brominated BDEs did not. Air-soil fugacity fractions were calculated, and these indicated that most compounds are undergoing net deposition from atmosphere to soil, with the higher brominated PBDEs furthest from equilibrium.