EPA discontinues use of exposure modeling thresholds in review of new chemicals


Aug. 25, 2022

In an announcement made on August 22, 2022, the Environmental Protection Agency (EPA) has discontinued the use of exposure modeling thresholds when assessing the human health and environmental risks of new chemicals under the Toxic Substances Control Act. This change in policy is in keeping with the Biden Administration’s environmental justice efforts to protect those communities living in close proximity to facilities emitting toxic substances.

Key Details

  • Under the Toxic Substances Control Act’s (TSCA) New Chemicals program, tens of thousands of submissions of pre-manufacture notices (PMNs) have been reviewed over the past 20 years with the use of exposure modeling thresholds that were programmed to not consider risks from releases to the air or emissions of toxic substances below a certain threshold amount. Instead, this policy focused on exposures with the greatest potential to affect human health and the environment and took into account EPA’s limited resources to review PMNs. The idea was that risks from releases of smaller amounts to air or from landfills would pose minor risks to human health and the environment.
  • Since 2021, the EPA has been re-evaluating policies to ensure they adhere to the Biden Administration’s executive orders and policies such as Executive Order 13985, Advancing Racial Equity and Support for Underserved Communities Through the Federal Government, which is to advance equity, and revise government policies and programs impacting underserved communities.
  • The communities surrounding facilities and landfills known as “fenceline communities” may be affected by these low level yet continuous toxic emissions since they may affect the air the residents breathe and the water they drink. Consequently, low emissions from new chemicals that were deemed to be of little consequence will be reviewed by assessors for their effects on human health and the environment.

Regulatory Context

  • On June 22, 2016, the “Frank R. Lautenberg Chemical Safety for the 21st Century Act” was signed into law, amending the 1976 Toxics Substances Control Act (TSCA) (15 U.S.C. § 2601 et seq., 2016 ). TSCA requires EPA to make an affirmative determination on whether a new chemical presents an unreasonable risk to human health or the environment under known, intended or reasonably seen conditions of use for every new chemical substance.
  • TSCA Section 5, which was amended in December 2019, governs chemicals that are not listed on the TSCA Inventory. In effect, substances listed on the Inventory are considered “existing chemicals.” Any chemical not listed on the Inventory is considered a “new chemical substance.” Entities planning on manufacturing or importing a new chemical must submit a pre-manufacture notice to EPA 90 days before any activity is initiated.
  • A pre-manufacture notice, or PMN, must include several key types of information to be considered by EPA risk assessors about the chemical (identity, structure and formula), the process for its manufacture (diagram and description, volume, byproducts, impurities), its intended uses, environmental releases and exposure, and related testing data on the effects on human health and the environment, as well as disposal.
  • Exposure modeling thresholds will no longer be used in the review of new chemicals PMNs that may have low emissions and/or apply the Low Releases and Low Exposures (LoREX) exemption for new chemicals under TSCA. The exposure modeling threshold was established under LoREX criteria. For LoREX, the submitter must show there are no exposures to consumers and low or no exposure to the general public in the proposed manufacturing, processing, or uses of the substance. In addition, any worker exposure must be adequately controlled through engineering controls, work practices, and/or use of personal protective equipment.
  • For ambient surface water releases, the limit is 1 part per billion using the prescribed calculation. Ambient air releases from incineration must not exceed 1 microgram per cubic meter maximum annual average calculation. No releases to groundwater are permitted unless the manufacturer has demonstrated negligible groundwater migration.
  • The notice is submitted using EPA’s e-PMN software via the Central Data Exchange (CDX) where submitters can submit the application and supporting documentation

Environmental Justice

  • EPA review of new and existing chemicals takes into account releases of chemicals to the air, water, and soil. If the facility is located in proximity to a community where people live and work, those residents may be affected by emissions to air, and/or discharges to water and soil more than a person who does not live near a facility producing or using a chemical substance.
  • President Biden has been focused on the effect of these chemical emissions to the environment and human health since the early days of his administration and issued Executive Order 13990 of January 20, 2021, Protecting Public Health and the Environment and Restoring Science to Tackle the Climate Crisis (86 FR 7037), and Executive Order 13985 of January 25, 2021, Advancing Racial Equity and Support for Underserved Communities Through the Federal Government. (86 FR 7009).
  • Last year the EPA began revising its review of existing chemicals under TSCA to better align with the Administration’s objectives of protecting human health and the environment, taking into account those communities close to the fenceline of facilities exposed to chemical air emissions and discharges to water and soil. TSCA requires the Agency to “conduct risk evaluations…to determine whether a chemical substance presents an unreasonable risk of injury to health or the environment, without consideration of costs or other non-risk factors, including an unreasonable risk to a potentially exposed or susceptible subpopulation identified as relevant to the risk evaluation by the Administrator, under the conditions of use.”
  • To better evaluate the effects that potential chemical exposure and associated risks might have on so-called fenceline communities, in January 2022, the EPA proposed a Draft Screening Level Approach for Assessing Ambient Air and Water Exposures to Fenceline Communities (screening level methodology). According to the methodology, EPA evaluates potential exposures and associated potential risks to human health in proximity to facilities releasing chemicals to the ambient air, and waterbodies receiving facility discharges (direct or indirect) of chemicals.
  • EPA defined “fenceline communities” in its screening level methodology as “members of the general population that are in proximity to air emitting facilities or a receiving waterbody, and who therefore may be disproportionately exposed to a chemical undergoing risk evaluation under TSCA section (6).”
  • The definition maintains different standards to measure the effects of chemical exposures to communities depending on the potential route of exposure. For air emissions, EPA establishes the proximity of fenceline communities to those less than or equal to 10,000 meters from a facility releasing chemicals to the ambient air. For evaluated aquatic exposure routes, proximity of the identified waterbody receiving a facility discharge does not have a specific associated distance but extends to those members of the community that may interact with the receiving waterbody and may be exposed. Downstream users can be miles away.
  • In its announcement EPA contends that by removing the modeling thresholds for the review of new chemicals, EPA will be better able to understand potential risks posed by releases of those chemicals not only to the general population but also to the overburdened and vulnerable communities, in keeping with the Environmental Justice objectives of the Biden Administration.

Next Steps

  • According to the announcement, EPA will update procedures “as soon as feasible” for New Chemical reviews and make “minimal changes to the coding in our New Chemical Review application to remove the thresholds.” EPA will also update procedures and training materials for EPA’s exposure and human health risk assessors.
  • Despite the ongoing personnel and technology resource challenges the EPA has been facing for the past few years, the agency states the changes will have “minimal impacts to the amount of time it takes to complete a new chemical review.” EPA explains that this is due to in part, the technical progress made in automated modeling calculations.
  • The EPA did not provide a scientific basis for discontinuing the use of the existing modeling thresholds, other than to state, “Completing the modeling for all potential exposures (rather than only those above an established threshold) that may result from air releases (fugitive and stack from industrial/commercial sites) and releases to groundwater from landfills will allow for a more fulsome understanding of the potential risks to these communities.”
  • EPA Administrator Michael Regan has conducted environmental justice tours and made this statement on August 3, 2022, concerning the ethylene oxide facilities used to sanitize medical devices and their surrounding communities, “Under my watch, EPA will do everything we can to share critical information on exposure risk to the people who need and deserve this information, and to take action to protect communities from pollution.” For more on efforts concerning emissions from ethylene oxide sterilization facilities and their effect on surrounding communities please see this article, EPA reaches out to communities exposed to ethylene oxide emissions from commercial sterilizers.
  • Those entities submitting PMNs should be aware that going forward, emissions no matter how low will be reviewed by assessors for impacts to human health, the environment, and disposal without use of the modeling thresholds and perhaps on a case by case basis.

To contact the author of this item, please email Patricia Iscaro.
To contact the editor of this item, please email Alexander Gaffney

Key Documents and Dates

Get an insider’s view on regulatory movements.

Sign up for AgencyIQ’s newsletters to receive exclusive regulatory updates and analysis impacting the life sciences or chemical industry.

Copy link
Powered by Social Snap