The U.S. Environmental Protection Agency (EPA) released on August 28, 2014, final risk assessments for three Toxic Substances Control Act (TSCA) Work Plan chemicals -- methylene chloride or dichloromethane (DCM), antimony trioxide (ATO), and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8,-hexamethylcyclopenta-[?]-2-benzopyran (HHCB). The much anticipated release of these assessments marks a real milestone for EPA's Office of Chemical Safety and Pollution Prevention (OCSPP), and EPA is to be commended for its efforts in completing these assessments in a reasonable period of time. EPA states that its risk assessment for DCM, which is widely used in paint stripping products, indicates health risks to both workers and consumers who use these products, and to bystanders in workplaces and residences where DCM is used. The risk assessments for ATO, which is used as a synergist in halogenated flame retardants, and HHCB, which is used as a fragrance ingredient in commercial and consumer products, did not show concerns. More information is available online.
In the final risk assessment, EPA describes DCM as "a volatile organic compound (VOC) that is used as a solvent in a wide range of industrial, commercial and consumer use applications, such as adhesives, paint stripping, pharmaceuticals, metal cleaning, chemical processing, and aerosols. It is the primary ingredient in many paint stripping products." EPA's Office of Pollution Prevention and Toxics (OPPT) "identified DCM for further evaluation based on its likely carcinogenic properties in humans, high potential for human exposure as it is widely used in consumer products, and reported releases to the environment. For instance, DCM has been detected in drinking water, indoor environments, ambient air, groundwater and soil." The risk assessment identifies cancer risk concerns and short-term and long-term non-cancer risks for workers and "occupational bystanders" (other workers within the facility who are indirectly exposed) from the use of DCM-containing paint strippers. The final risk assessment also identifies short-term non-cancer risks for consumers and residential bystanders from the use of DCM-containing paint strippers.
According to EPA, it is considering a range of possible voluntary and regulatory actions to address concerns. Options include transitioning to safer chemicals and greener processes/technologies, promoting best practices, and phasing out uses. EPA anticipates conducting a workshop in late fall 2014 to engage key stakeholders and the public on potential alternatives and risk reduction approaches. In the meantime, EPA recommends that consumers check the label to determine if the product contains DCM or methylene chloride. If so, EPA states that it "recommends taking precautions that can reduce exposures, such as using the product outside or in an extremely well-ventilated area and wearing protective equipment." More information, including a response to comments and a consumer fact sheet on DCM, is available online.
The final risk assessment addresses effects on ecological receptors from the use of ATO as a synergist in halogenated flame retardants. The final risk assessment states that EPA's OPPT identified key sources of uncertainty related to limitations in the available hazard and exposure information, and conservative assumptions incorporated in the Exposure and Fate Assessment Screening Tool, version 2 (E-FAST2) model estimates of antimony surface water concentrations. According to the assessment, although these uncertainties may limit data interpretation, "EPA/OPPT has high confidence in its minimal risk finding based on the following considerations":
The use of release data for antimony compounds and conservative assumptions incorporated in the EFAST-2 model estimates likely overestimate ATO exposure potential; and
Environmental monitoring data obtained during the last three years show no exceedances of the hazard benchmarks identified to be protective of sensitive ecological species.
More information, including a response to comments, is available online.
According to the final risk assessment, "HHCB is one of the most widely used polycyclic musk fragrance ingredients in a range of consumer products including perfumes, cosmetics, shampoos, lotions, detergents, fabric softeners, and household cleaners." Although HHCB is not produced in the U.S., it is imported and compounded into fragrance oils, which are blended into end-use products and sold for both commercial and consumer use. Problem formulation resulted in the assessment focusing on environmental risk to the aquatic environments from the use of HHCB as a fragrance ingredient in consumer and commercial products. The final risk assessment states that, under the exposure scenarios assessed, "current environmental exposure concentrations are one to two orders of magnitude below hazard concentrations (RQs < 1) of concern for aquatic or sediment-dwelling organisms." The final risk assessment notes that "[t]he inability to assess potential risks to terrestrial invertebrates and plants is a major uncertainty associated with this assessment." More information, including a response to comments, is available online.
EPA prepared the final risk assessments as part of its TSCA Work Plan, which identified chemicals for review and assessment of potential risks to people's health and the environment. EPA states that it based the risk assessments "on the best available information" and prepared the final risk assessments "after careful consideration of comments from the public and experts during an independent, scientific peer review of the assessments."
In its August 28, 2014, press release, EPA notes that it is also currently evaluating risks of another chemical in paint strippers, n-methylpyrrolidone (NMP). EPA released a draft risk assessment for NMP that identified risks associated with use of NMP-containing paint strippers. EPA states that it "does not expect the final risk assessment to significantly change this conclusion, and therefore recommends that those using NMP-containing paint strippers also take measures to minimize exposure."
The release of these assessments reflects OCSPP's sustained commitment to use its TSCA authority to the maximum extent, and not rely upon the vagaries of the legislative process to ensure chemical substances targeted for review under TSCA are assessed, measures are implemented when uses are determined to present unreasonable safety risks, and OPPT findings that a chemical presents minimal risk are communicated. That these and other assessments have been completed, within a reasonable period of time, and through a deliberative process that invites significant stakeholder engagement is a significant achievement of which OCSPP Assistant Administrator Jim Jones and his team should be proud. The release of these assessments offers yet another reminder to chemical producers and downstream users and product formulators to be mindful of the opportunities presented for new chemical alternatives believed to be safer than those for which EPA has identified clear risks to targeted users, as in the case of DCM. The pressures on product manufacturers to select the safest and most efficacious chemical ingredients in their products can only be expected to increase.