Another EPA risk evaluation grossly understates risks, this time of 1-bromopropane

Richard Denison, Ph.D., is a Lead Senior Scientist.

On Friday EDF filed detailed comments with the Environmental Protection Agency (EPA) critical of its draft risk evaluation for the carcinogenic solvent, 1-bromopropane (or 1-BP).  As was the case with 1,4-dioxane, EPA has grossly understated the risks from exposure to this chemical, for both cancer and non-cancer health effects.  EPA has also inappropriately dismissed human studies that show neurological effects at 1-BP exposures lower than EPA assumed to be safe.

While the draft risk evaluation did find that some uses of 1-BP present unreasonable risks, even in those cases it understated the extent of the risk – which, if not ameliorated, means that any regulation it subsequently promulgates will be under-protective.

EPA has also abdicated its responsibility under the Toxic Substances Control Act (TSCA) to identify and evaluate the risks the chemical presents to consumers and the general population by excluding from its risk evaluation conditions of use and exposures that are known or reasonably foreseen.  EPA has not met its mandatory duty under TSCA to thoroughly identify and evaluate the risks to vulnerable subpopulations.  EPA has utterly failed to utilize the enhanced authorities Congress granted it in 2016 to ensure that it has or obtains robust information on 1-BP’s uses, hazards and exposures, resulting in serious information and analytic gaps and deficiencies that severely undermine the scientific quality of its risk evaluation.

Below we list major concerns that EDF addressed in our comments (with references to the corresponding section of the comments). 

Cross-cutting concerns

• EPA has failed to sufficiently identify and address potential hazards, exposures, and risks of 1-BP to several vulnerable subpopulations (see section 1.A).
• EPA has distorted OSHA requirements and over-relied on personal protective equipment and safety data sheets, ignoring their real-world limitations (see section 1.B).
• EPA has distorted the nature of information that companies submitted to the European Chemicals Agency and has relied on industry-prepared summaries without access to the full studies (see section 1.C.i and ii). EPA must obtain and make public the full studies.
• EPA’s risk evaluation lacks an adequate mass balance to account for the lifecycle of 1-BP (see section 1.C.iii).

Unwarranted exclusions of conditions of use and exposure pathways

• EPA has excluded or overlooked specific conditions of use without providing adequate documentation or rationale (see section 2.A).
• EPA has excluded from its risk evaluation all general population exposures to 1-BP from releases to air and land, based on EPA’s unsupported assertion that existing regulatory programs under other statutes EPA administers have addressed or are in the process of addressing potential risks of 1-BP in these media pathways (see section 2.B).
• EPA has collapsed into a single category a highly diverse set of industrial/commercial uses that encompass a huge array of sectors, from hobby materials to construction materials to laboratory chemicals, and very different functional uses (see section 2.C).
• EPA has ignored 1-BP’s use in spray foam blowing and as a flame retardant without providing any rationale (see section 2.D).

Need to adopt a linear, no-threshold approach for 1-BP’s carcinogenicity

• EPA must maintain its adoption of a linear, no-threshold approach for 1-BP’s carcinogenicity, based on the available evidence and scientific and health-protective principles (see section 3.A.-E).
• EPA should migrate to a unified approach to presenting dose-specific population risks for both cancer and noncancer endpoints (see section 3.F).

Serious data gaps

• EPA’s determination of no unreasonable risk to the environment is not supported by sufficient evidence (see section 4.A).
• EPA’s occupational exposure assessment is not supported by sufficient use information, dermal toxicity data, or inhalation or dermal exposure data (see section 4.B).

Analytic gaps and deficiencies

ENVIRONMENT

• EPA’s disregard of environmental monitoring data led to an overreliance on predictive modeling lacking adequate uncertainty analysis (see section 5.A.i).
• EPA has inappropriately dismissed sediment and terrestrial toxicity and exposure pathways (see section 5.A.ii).
• EPA over-relies on limited and incomplete TRI data to exclude or dismiss the significance of numerous releases and exposure pathways (see section 5.A.iii).

HUMAN HEALTH

• EPA has illegitimately dismissed human studies of 1-BP exposure (see section 5.B.i).
• EPA has excluded without justification identified hazards of 1-BP from its quantitative risk characterization (see section 5.B.ii).
• EPA has failed to apply all necessary uncertainty factors in calculating the benchmark margins of exposure, resulting in inaccurate risk characterizations (see section 5.B.iii).
• EPA has failed to consider cancer risk from acute exposure scenarios (see section 5.B.iv).
• EPA has failed to identify and analyze risks to people living in proximity to conditions of use and sources of contamination and environmental release (see section 5.B.v).
• EPA fails to consider combined exposures to workers from different routes and sources and has omitted a number of workplace-related exposure scenarios (see section 5.B.vi and vii).
• EPA may have underestimated risks to occupational non-users (ONUs) and has inadequately addressed uncertainties in its dermal risk estimates (see section 5.B.viii and ix).
• EPA appears to have ignored a significant source of data on inhalation exposure (see section 5.B.x).
• EPA has failed to explain or justify its assumption of one exposure event per day (see section 5.B.xi).
• EPA has failed to address exposure and risk to children, a susceptible subpopulation, from 1-BP’s use in dry cleaning (see section 5.B.xii).
• EPA has inadequately assessed consumer exposures to insulation (see section 5.B.xiii).

Understating risks to workers

• EPA has significantly understated both the extent of its unwarranted assumption of PPE use by workers and the risks to workers it has identified (see section 6.A).
• EPA’s assessment of dermal risk likely underestimates exposure due to its crude assumptions about glove use and efficacy (see section 6.B).
• EPA’s approaches to both aggregate and sentinel exposures are flawed (see section 6.C).

Flaws (and one bright spot) in EPA’s unreasonable risk definition and determinations

• EPA’s “expectation” of compliance with existing laws and standards as a basis for not finding unreasonable risk is unwarranted (see section 7.A).
• EPA appropriately found unreasonable risk when high-end risk exceeds relevant benchmarks, an approach that is needed to be adequately protective (see section 7.B).
• EPA’s allowance of a 1 in 10,000 cancer risk for workers is a major and unwarranted deviation from longstanding agency policy and practice to regulate upon finding cancer risks on the order of 1 in 1 million (see section 7.C).
• EPA’s assumptions of PPE use and a 1-in-10,000 acceptable risk levels for workers conflates risk evaluation and risk management and significantly understates risk (see section 7.D).
• EPA’s characterizations of its dermal risk analysis in its risk determinations are misleading and flawed (see section 7.E).

Flaws in EPA’s systematic review

• OPPT does not provide explanation or empirical support for its revisions to the systematic review data quality criteria for epidemiological studies, and certain revisions make it more difficult for epidemiological studies to be scored overall as high quality (see section 8.A).
• OPPT’s approach taken to evidence integration in the draft 1-BP risk evaluation does not align with best practices as reflected and shared by leading systematic review methods for chemical assessment (e.g., OHAT, NavGuide, IRIS) (see section 8.B).
• OPPT’s inconsistent application of its systematic review criteria results in an arbitrary and capricious analysis (see section 8.C).
• EPA inappropriately excluded from systematic review several studies because they were in other languages and EPA had failed to request them (see section 8.D).