US EPA Outlines TSCA Risk Evaluation Path for Five Phthalates
The US EPA has said it will soon begin releasing draft TSCA risk evaluations and technical support documents related to its review of five high-priority phthalates, ahead of a public peer review in spring 2025.
The 2 December announcement signals the first forward progress in years for evaluations the EPA initiated in December 2019 on the phthalates BBP, DBP, DEHP, DIBP and DCHP (see box).
The agency set out its plans for the phthalates in a recent call for nominations of experts to assist the Science Advisory Committee on Chemicals (SACC) in peer reviewing "a large number of technical support documents" related to the five reviews.
The agency said these documents will be released over the next six months, beginning with the DCHP draft risk evaluation and associated supporting documents, which are expected before the end of the year.
Chemical-specific technical support documents will be released "in batches" ahead of each draft risk evaluation, the EPA said. A formal 60-day public comment period will begin once the agency publishes a chemical's full risk evaluation, it said.
In total, the agency said it anticipates six opportunities for public comment – five related to the specific evaluations, and a sixth tied to the upcoming SACC peer review addressing all five chemicals.
The EPA said it plans to announce a schedule in early December specifying the planned timeline to issue all of the evaluation materials.
SACC review
The SACC review next spring will focus on the DCHP draft risk evaluation and technical support documents relevant to all five chemicals, the EPA said.
The technical documents address:
physico-chemical and environmental fate;
ecological hazard;
cancer and non-cancer human health hazard;
environmental releases and occupational exposure;
environmental and general population exposures from environmental releases; and
consumer and indoor air exposure.
The peer review panel will also offer feedback on a draft cumulative risk assessment (CRA) the EPA developed to better understand the combined effects of the five phthalates, along with a sixth, DINP.
The CRA document, which the EPA said incorporates SACC comments on a proposed version released last year, calculates relative potency factors for ‘phthalate syndrome’ for each of the six chemical substances. This calculation is "based on a pooled dataset for assessing foetal testicular testosterone health endpoint and estimates cumulative non-attributable exposures from NHANES [the National Health and Nutrition Examination Survey] urinary biomonitoring data", the agency said.
The EPA plans to issue draft peer review charge questions during the first quarter of 2025, addressing "critical inputs and novel approaches contained in these documents".
According to the agency, the anticipated review will "constitute full peer review of the phthalate risk evaluations".
SACC nominations are due 2 January.
High-priority phthalates
The latest announcement addresses five phthalates designated as TSCA high-priority chemicals five years ago:
benzyl butyl phthalate (BBP);
dibutyl phthalate (DBP);
di(2-ethylhexyl) phthalate (DEHP);
diisobutyl phthalate (DIBP); and
dicyclohexyl phthalate (DCHP).
According to the EPA, the substances are primarily used as plasticisers in polyvinyl chloride (PVC) products and in adhesives, sealants, paints, coatings, rubbers and other applications.
The agency said it chose to assess the phthalates’ cumulative impacts and develop the risk evaluations in parallel due to "significant similarities in exposure and physical chemical properties".
The EPA is also close to finishing TSCA risk evaluations for two other phthalates nominated for review by industry: diisodecyl phthalate (DIDP) and diisononyl phthalate (DINP).
The EPA said it incorporated SACC recommendations from these manufacturer-requested risk evaluations (MRREs) in its reviews of the latest five phthalates.