Scientists Critique EPA’s Draft Evaluation of Phthalate DCHP

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A collection of scientists, academics, and clinicians have called for “extensive revisions” to EPA’s draft risk evaluation for dicyclohexyl phthalate (DCHP), arguing that the assessment “failed to incorporate the best available science and makes a number of scientifically unsupported assumptions.”

The May 9 comments were submitted by the Program on Reproductive Health and the Environment at the University of California San Francisco.  The commenters raise a number of methodological concerns with EPA’s December 2024 draft, which preliminarily determined that nine of 24 evaluated conditions of use for DCHP raised concerns, all involving occupational exposures.

A central criticism is EPA’s reliance on central tendency estimates, rather than high-end exposure scenarios, for many conditions of use. This approach, the commenters argue, “sets a dangerous precedent that risks to more highly exposed individuals can be dismissed or downplayed without scientific support.”

The commenters also object to EPA’s blanket exclusion of human epidemiology studies from its dose-response assessment, justified by uncertainties over exposures and testing methods.  That rationale “demonstrates a bias against environmental epidemiology, rather than a thoughtful approach to evidence evaluation that is consistent with best practices in systematic review,” according to the comments.

The group additionally claims that EPA failed to conduct an up-to-date literature search, omitting certain studies conducted since 2019.  As a result, they argue that the draft overlooks newer evidence linking DCHP to liver toxicity.

Alongside the Toxic Substances Control Act (TSCA) risk evaluation, DCHP is also part of EPA’s first-ever cumulative risk assessment for a group of six phthalates. A blog post on that effort, published prior to the January 2025 draft, can be found here.

EPA Announces Intent to Reconsider Risk Evaluation Framework Rule

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The Trump EPA announced in a March 10, 2025 press release that it will reconsider the Biden-era risk evaluation framework rule governing assessments of existing chemicals under the Toxic Substances Control Act (TSCA).

As discussed in a previous blog post, the risk evaluation framework rule replaced regulations promulgated by the first Trump administration.  The Biden-era rule reversed key policies by requiring the agency to consider all conditions of use of chemical, issue a single risk determination rather than use-by-use determinations, and not assume that workers use PPE.

According to the press release, specific policies in the rule that EPA will review include:

  • The single risk determination approach;
  • Whether EPA “must evaluate all conditions of use of a chemical at the same time” during an evaluation;
  • “Whether and how” use of PPE and industrial controls in occupational work environments should be incorporated; and
  • “[R]egulatory definitions expanded by the Biden Administration.”

The rulemaking process is set to begin “in the near future.”

Ongoing Litigation

On the same day as the press release, EPA filed a motion for voluntary remand in a consolidated D.C. Circuit case challenging the risk evaluation framework rule.  The court previously denied EPA’s February motion to hold that case in abeyance.

“EPA’s reconsideration is consistent with agencies’ implicit authority to reconsider past decisions, particularly in light of a change of administration and attendant change in policy priorities and approach to statutory interpretation,” the motion for voluntary remand states.

There are also ongoing as-applied challenges to the rule, including a Fifth Circuit suit challenging EPA’s risk evaluation for methylene chloride.  The court granted an EPA motion to hold that case in abeyance in February despite industry opposition, but reversed its decision a week later without explanation.

A post on the D.C. Circuit case can be found here.  More on the methylene chloride suit can be found here.

Briefs Filed in Sweeping Challenge to EPA’s Methylene Chloride Rule

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Opening briefs have been filed by industry petitioners, the Sierra Club, and EPA in a case challenging EPA’s 2024 rule banning most uses of methylene chloride.  The lawsuit has critical implications not only for EPA’s regulation of the solvent but for future risk management rules and risk evaluations promulgated under the Toxic Substances Control Act (TSCA).

The case, East Fork Enterprises Inc. v. EPA, No. 24-60256, is before the Fifth Circuit.  Industry petitioners are requesting that the court vacate the methylene chloride rule and its underlying risk evaluation in their entirety.  The Sierra Club, taking the opposite position, contends the rule does not go far enough but seeks only a remand to EPA without vacatur.

“Extreme” Risk Evaluation

One of the central arguments in the industry petitioners’ October 9 brief is that EPA’s methylene chloride risk evaluation conflated the potential for any harm with “unreasonable risk,” the threshold for regulation under TSCA.  “EPA treated a use as risky if there was even a theoretical possibility of health risks,” the brief states, a stance described as “contrary to the statutory text and Congress’s regulatory structure.”

The industry petitioners argue this approach represents massive EPA overreach.  “Under EPA’s extreme (and incorrect) reading of TSCA, EPA can prohibit a wide range of commercial activities simply by saying a chemical substance poses unreasonable risk,” the brief continues.

In its opening brief, filed December 13, EPA argues that the agency has sole discretion to determine what constitutes unreasonable risk.  “Congress assigned to EPA the task of determining what risks are ‘unreasonable’ for a given chemical substance based on EPA’s scientific and technical expertise,” the agency states.  “Applications of that expertise are entitled to the Court’s respect.”

Last term, the Supreme Court struck down Chevron deference—a longstanding precedent requiring courts to defer to “permissible” agency interpretations of statutes they administer—in Loper Bright v. Raimondo. Nevertheless, EPA cites Loper Bright, emphasizing language clarifying that the Administrative Procedure Act “mandate[s] that judicial review of agency policymaking and factfinding be deferential.”

The industry petitioners also contend two policy reversals made by the Biden EPA regarding risk evaluations: the adoption of a “single determination” of a chemical’s risk and the removal of the assumption that workers use personal protective equipment. These changes led the Biden EPA to replace a Trump-era methylene chloride risk evaluation with a revised version in 2022.

“Assumption Upon Assumption”

Other industry attacks focus on the risk management rule’s stringent limits on methylene chloride exposure concentrations, which are significantly lower than OSHA’s.  According to the industry petitioners, EPA ignored human exposure studies, relied on a single rat study, and “piled assumption upon assumption upon uncertainty” to reduce the acceptable exposure level “100-fold.”

In response, EPA contends that the industry petitioners misunderstand the toxicology underlying the limits. The agency also defends its use of “uncertainty factors” to extrapolate findings from limited studies, including a policy of basing certain calculations on the 1st percentile of human susceptibility to ensure more conservative protections.

These strict exposure limits prompted EPA to ban many uses of methylene chloride in the risk management rule. EPA argues that it had reason to believe compliance with the limits was not feasible for the banned uses, while the industry petitioners claim the bans were implemented “simply because EPA was uncertain whether businesses would be able to comply with EPA’s new exposure limits.”

Fenceline Communities

The Sierra Club’s challenge is comparatively narrow, primarily focusing on methylene chloride’s risks to fenceline communities.  In a supplement to its risk evaluation, EPA found that methylene chloride air releases elevated cancer risks in these communities.  However, EPA “never determined whether those risks are unreasonable” and “fail[ed] to address those risks” in the risk management rule, the Sierra Club’s October 9 brief states.

In its brief, EPA acknowledges that it “identified some existing risk to fenceline communities” but argues that the risk management rule “adequately address[es] that risk.”  TSCA does not require EPA to “formally determine” whether the risks identified in the supplement were unreasonable because it was conducted after the risk evaluation was completed, the brief argues.  Instead, EPA “opted to factor in the potential risk to fenceline communities as a human health effect that informed the Rule’s choice of restrictions.”

The Sierra Club also challenges EPA’s failure to evaluate the risk methylene chloride poses to the ozone layer, while EPA maintains that the chemical “is not an ozone depleting substance.”

More on EPA’s methylene chloride risk management rule can be found here.

EPA Initiates Risk Evaluations for Five Chemicals, Begins Prioritizing Five More

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On December 18, 2024, EPA designated five chemicals as high-priority substances, automatically initiating risk evaluations for them under the Toxic Substances Control Act (TSCA).  In a separate rulemaking, EPA also initiated the prioritization process for another round of five substances.

The five chemicals now undergoing risk evaluations are:

  • Vinyl chloride (CASRN 75-01-4)
  • Acetaldehyde (CASRN 75-07-0)
  • Acrylonitrile (CASRN 107-13-1)
  • Benzenamine (CASRN 62-53-3)
  • 4,4’-methylene bis(2-chloroaniline) (MBOCA) (CASRN 101-14-4)

More on those substances can be found here.

The five chemicals newly identified for prioritization are:

  • 4-tert-Octylphenol (CASRN 140-66-9);
  • Benzene (CASRN 71-43-2);
  • Ethylbenzene (CASRN 100-41-4);
  • Napthalene (CASRN 91-20-3); and
  • Styrene (CASRN 100-42-5).

According to EPA, benzene is a known carcinogen while ethylbenzene, naphthalene, and styrene are probable carcinogens.  4-tert-octylphenol may cause kidney inflammation and impaired fertility.  All five chemicals were selected from the 2014 TSCA Work Plan and have uses in consumer products.  National production volumes range from tens of millions to tens of billions of pounds annually, according to Chemical Data Reporting (CDR) data.

Comments on EPA’s initialization of prioritization are due March 18, 2025.  There will be another opportunity for comment when the agency formally proposes to designate these substances as high priority, which will likely occur in summer 2025.

All 10 chemicals are also covered by a recently finalized health and safety reporting rule, which applies to 16 substances in total.  A blog post on the rule is forthcoming.

EPA to Release Phthalate Cumulative Risk Assessment

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On December 10, 2024, EPA announced its schedule for completing Toxic Substances Control Act (TSCA) risk evaluations for five phthalates: BBP, DBP, DEHP, DIBP and DCHP.  In the next few weeks, EPA expects to release a draft risk evaluation for DCHP and a slew of supporting documents—including a first-of-its-kind cumulative risk assessment (CRA) for six phthalates as a class.

The CRA will mark the first time EPA has evaluated the combined risk to health from multiple chemicals with similar effects under TSCA section 6.  It is intended to inform, rather than replace, individual risk evaluations for each phthalate.

EPA justified the CRA in a draft proposal released in February 2023.  According to the agency, studies have shown “widespread exposure to some phthalates and that humans may become co-exposed to multiple phthalates at the same time,” possibly due to their use in food contact materials.  A particular concern is “phthalate syndrome,” a collection of adverse effects on the developing male reproductive system.

In the draft proposal, EPA announced the agency’s plan to address phthalate syndrome by focusing on the most sensitive effect rather than assessing the syndrome as a whole.  EPA also proposed to consider exposures to these substances from “non-TSCA exposures,” such as dietary intake, and to assess the phthalates “under an assumption of dose addition” using “a relative potency factor approach.”

Meanwhile, final risk evaluations for two additional phthalates, DIDP and DINP, are nearing release.  The risk evaluations for these substances were initiated at the request of the companies that produce them.  EPA intends to include DINP—but not DIDP—in its cumulative risk analysis.

Draft risk evaluations for BBP, DBP, DEHP, and DIBP are expected in the first quarter of 2025.  According to the December 10 announcement, final risk evaluations “will be released by December 2025.”

EPA Reworks its Regulations for PBTs DecaBDE and PIP (3:1)

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On November 19, 2024, EPA published a final rule revising its Toxic Substances Control Act (TSCA) regulations for decaBDE and PIP (3:1), two persistent, bioaccumulative, and toxic (PBT) chemicals.  The rule generally lessens burdens on industry stakeholders, who argued that the original PIP (3:1) risk management rule would lead to significant supply chain disruptions.

The final rule excludes from prohibition certain uses of PIP (3:1) in lubricants, greases, wire harnesses, and circuit boards.  Phased-in prohibitions for PIP (3:1) in marine antifouling coatings and manufacturing equipment, including the semiconductor industry, are now delayed until 2029 and 2034, respectively.  And, in response to comments, the rule allows for the “processing and distribution in commerce for maintenance and repair of existing PIP (3:1)-containing articles.”

On the other hand, the rule subjects motor vehicle and aerospace vehicle parts—which were excluded from prohibition under the original rule—to phased-in PIP (3:1) prohibitions that take effect in 2054.  EPA also finalized worker protection requirements during PIP (3:1)’s manufacturing and processing.

As for decaBDE, EPA determined that no alternative to decaBDE-containing wire and cable insulation is available for use in nuclear power plants and therefore extended the compliance date for this use until after the end of the wire and cable service life.  All other changes to the decaBDE regulations—for which supply chain disruptions were a lesser concern—impose new requirements rather than diminishing existing ones.  These include mandating signage in regulated areas, requiring worker protections for certain activities, and prohibiting releases to water.

Importantly, the rule also implements a de minimis standard for the already-effective general prohibitions on the manufacture and distribution of decaBDE and PIP (3:1)-containing products and articles.  Products and articles unintentionally containing less than 0.1% of either PBT by weight will now be exempt.

PIP (3:1) Litigation

The rule is likely to resolve a D.C. Circuit case challenging EPA’s risk management rule for PIP (3:1).  In a recent court filing in Conditioning, Heating, and Refrigeration Inst. v. EPA, No. 21-1082, the agency said that its release “could obviate the need for further proceedings.”

That case was held in abeyance from 2022 until September as EPA pursued the rulemaking.  In the meantime, EPA repeatedly delayed certain phased-in prohibitions for PIP (3:1) and provided a no action assurance on enforcement of the rule.

The rule’s effective date—January 21, 2025—means that its implementation could be delayed by the incoming administration, however.

More on EPA’s actions to delay the PIP (3:1) rule’s compliance deadlines can be found here.  A blog post on the November 2023 proposed rule can be found here.

Court Approves Tight Deadlines for Overdue Risk Evaluations

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The D.C. District Court has entered two consent decrees concerning over twenty overdue Toxic Substances Control Act (TSCA) risk evaluations, holding the incoming administration’s EPA to aggressive deadlines for completing the chemical reviews.

The consent decrees, approved November 22, concern 20 risk evaluations initiated by EPA in December 2019 and two manufacturer-requested risk evaluations initiated in January 2020.  None were completed within TSCA’s 3.5-year deadline.

Under the consent decrees, linked here and here, EPA will be required to complete:

  • Draft risk evaluations for six of the substances, including 1,3-butadiene, by December 31, 2024;
  • Final risk evaluations for TCEP, formaldehyde, 1,1-dichloroethane, and DIDP by December 31, 2024;
  • A final risk evaluation for DINP by January 15, 2025;
  • A draft risk evaluation for one of the remaining substances by March 31, 2025;
  • Final risk evaluations for seven of the substances, including 1,3-butadiene, by December 31, 2025; and
  • Final risk evaluations for the remaining 10 substances by December 31, 2026.

The deadlines are largely unchanged from those in the proposed consent decrees, released in April and discussed in a previous blog post.  Since then, EPA has released a final risk evaluation for TCEP and drafts for 1,1-dichloroethane, DINP, and 1,3-butadiene.  However, as it stands, EPA will be required to complete three more final risk evaluations before the end of 2025—and a fourth before the presidential transition.

Meanwhile, EPA looks likely to designate another five chemicals as “high priority” this December, automatically triggering new risk evaluations.  More on those chemicals can be found here.

Science Advisory Board to Review Co-exposure Approach to TSCA Risk Evaluations

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This October, the Science Advisory Board (SAB) received an EPA briefing on a proposed “screening level analysis” that could account for cumulative chemical exposures in Toxic Substances Control Act (TSCA) risk evaluations.

Released in September 2023, EPA’s draft approach is designed to support the identification of potentially exposed or susceptible subpopulations (PESS) and co-exposures with other chemicals.  It relies heavily on AirToxScreen, a modelling tool already used by EPA to estimate chemical inhalation exposure and risk at the national level.

The draft approach “can be used to better inform chemical co-exposure, highlight geographic areas or population groups that may experience disproportionate impacts, and identify areas that may need more targeted or higher tier exposure and risk characterization.”  It is not intended to be “used as a sole basis for health or regulatory action,” however.

Limitations to the draft approach include its narrow focus on industrial releases to air and reliance on annual data, which makes it impossible to determine whether releases occurred concurrently.  In addition, the model does not calculate “a total additive exposure or total additive risk across the chemicals included in the analysis.”

Historically, TSCA risk evaluations have evaluated a single chemical and considered routes of exposure separately.  However, in a slideshow from the October 15–16 SAB meeting, EPA noted that there is “wide acknowledgement in [the] scientific and regulatory community [that] multiple facility and chemical exposures” meaningfully intersect.

The agency also emphasized the environmental justice concerns tied to cumulative exposures, which disproportionately affect marginalized communities.

The SAB is expected to provide formal comments on the approach in the coming months.

Industry Petitioners Challenge EPA’s Use of TSCA to Regulate Workplace Chemical Exposures

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Industry petitioners are arguing before the D.C. Circuit that EPA has overstepped its authority under the Toxic Substances Control Act (TSCA) by assuming powers to regulate worker chemical exposures—powers that they argue that rightfully belong to OSHA.

United Steel Workers v. EPA, No. 24-1151, consolidates multiple cases challenging EPA’s May 2024 revisions to the procedures for TSCA risk evaluations.  That rule reversed key Trump-era policies by requiring the agency to consider all possible uses of a chemical, issue a single risk determination, and not assume PPE usage.

The industry petitioners, which include the Texas Chemistry Council and the American Chemistry Council, are challenging these changes in full.  However, their October 10 brief also questions EPA’s ability to circumvent OSHA’s role in regulating workplace chemical exposures, arguing that “TSCA is not, and was not intended to be, a worker protection law.”

Their arguments center on TSCA section 9, which allows EPA to report a chemical’s unreasonable risks to another agency if EPA believes they could mitigate the risks.  “In context, TSCA requires EPA to refer regulation of TSCA chemicals that pose unreasonable risks to workers to OSHA if regulation under the OSH Act may prevent or reduce risks of chemical exposure in the workplace,” the industry petitioners’ brief states.  “Only if the referral agency fails to act may EPA proceed to regulate those risks to workers.”

The industry petitioners additionally argue that EPA should give greater consideration to existing OSHA regulations, including those requiring the use of PPE, when considering chemical exposures to workers.  However, a collection of labor petitioners in the case contend that EPA should be prohibited from considering PPE entirely during risk evaluations, asserting that the agency’s approach “confuses risk evaluation with risk management.”

EPA has declined to exercise its referral powers in recent rulemakings, arguing that “gaps exist between OSHA’s authority to set workplace standards under the OSH Act and EPA’s obligations under TSCA section 6 to eliminate unreasonable risk.”  For example, according to EPA, OSHA must consider the economic and technological feasibility of regulation in circumstances where EPA does not.

More on EPA’s 2024 revisions to the procedures for TSCA risk evaluations can be found in a previous blog post.

EPA’s Draft Risk Evaluation of DINP Finds Minimal Risks, but Determines That the Phthalate Presents an Unreasonable Risk

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On August 30, 2024, EPA released its draft risk evaluation for diisononyl phthalate (DINP).  The draft risk evaluation determined that most uses of DINP under the Toxic Substances Control Act (TSCA) “do not pose risk to the environment or the general population.”

The draft only identified three uses that “raise concerns” out of 47 evaluated conditions of use.  However, EPA preliminarily found that DINP presents an unreasonable risk of injury to human health due to the agency’s “single risk determination” approach to risk evaluations.

Two of these three uses were found to raise concerns for workers: industrial use of adhesives and sealants and industrial use of paints and coatings, specifically in scenarios in which unprotected workers used high-pressure sprayers.  According to the draft, these uses could create high concentrations of DINP in mist that an unprotected worker could inhale.

The other use—use of DINP in construction and building materials that cover large surface areas—was found to raise concerns for consumers.  This use could result in young children inhaling DINP-containing dust that settles “onto vinyl flooring, in-place wallpaper, and carpet backing and [is] resuspended into the indoor environment,” the draft says.

The draft risk evaluation identified developmental toxicity and liver damage as potential health effects of these types of exposures.  DINP also has the potential to cause “phthalate syndrome,” a collection of adverse effects on the developing male reproductive system, EPA said.

According to EPA, DINP is primarily used as a plasticizer to manufacture flexible polyvinyl chloride, better known as PVC.  Data from the Chemical Data Reporting rule indicates that hundreds of millions of pounds of DINP are manufactured annually.

EPA initiated the risk evaluation process after a 2019 request from ExxonMobil Chemical Company to review DINP and its chemical relative diisodecyl phthalate (DIDP).  EPA only found one concerning condition of use in DIDP’s draft risk evaluation, which was released this May.

DINP is a category of chemical substances which include 1,2-benzene-dicarboxylic acid, 1,2-diisononyl ester (CASRN 28553-12-0) and 1,2-benzenedicarboxylic acid, di-C8-10-branched alkyl esters, C9-rich (CASRN 68515-48-0).

Amended TSCA requires EPA to issue a risk management rule to address any unreasonable risks found by the final evaluation.  Comments on the draft risk evaluation are due on November 4, 2024.