US EPA provides guidance and recommendations for using a simple time-weighted average approach to assess cumulative lead risks that consider intermittent or variable exposures at secondary non-residential locations.
In August 2024, the US Environmental Protection Agency (US EPA) released new guidance and recommendations for the assessment of cumulative lead risks when exposures occur at multiple sites, including primary residences (for children), non-residential sites (for adults), and secondary non-residential sites (for both children and adults). US EPA also provided guidance for deriving Preliminary Remediation Goals (PRGs) and simulating intermittent air lead exposure pathways using a time-weighted average (TWA) approach. According to the guidance, secondary lead exposure sites may include recreational areas (i.e., neighboring parks or playgrounds) or contaminated worksites and should be incorporated into modeling when media lead concentrations at secondary sites differ from primary sites. Figure 1 below, from the US EPA guidance document, summarizes when intermittent or variable lead exposures should be incorporated into lead exposure modeling under the new guidance:
US EPA stated that this new methodology is not intended to replace the typical residential approach of the Integrated Exposure Uptake Biokinetic (IEUBK) model (i.e., for children 12-72 months) and non-residential approach of the Adult Lead Methodology (ALM); rather, this new guidance is intended to supplement existing guidance. Previously, US EPA’s lead models focused on simulating lead exposures at a single location. US EPA recommends incorporating secondary exposure scenarios only if receptors are exposed at a secondary site for at least three months, with exposures occurring at least once every seven days. According to US EPA, the reliability of models in predicting blood lead concentrations has not been assessed when exposures occur less than once every seven days for at least three months.
According to the new guidance, there are several factors that could contribute to either an overestimation or underestimation of blood lead concentrations when time-weighted exposures to media concentrations are used as inputs to the IEUBK model and ALM, including:
In combination with recently lowered guidance levels for lead-contaminated soil in residential areas, US EPA’s new TWA approach may impact its cleanup recommendations. Further, PRGs derived using this new approach could prompt remediation efforts at both primary and secondary exposure sites. Earlier this year, US EPA released the final version of the All Ages Lead Model (AALM), which can simulate the impact of intermittent exposures on lead concentrations in children and adults. US EPA’s new TWA approach did not discuss the AALM or how the new guidance intersects with evaluating intermittent lead exposures using the AALM.
For more information, refer to US EPA’s website and/or contact Gradient.
Contact:
Steven R. Boomhower, Ph.D.
Senior Toxicologist
Steven.Boomhower@gradientcorp.com
Kyle J. Colonna, Ph.D., M.P.H.
Epidemiologist
Kyle.Colonna@gradientcorp.com
Rosemary L. Mattuck, M.S.
Senior Environmental Engineer
Rosemary.Mattuck@gradientcorp.com
September 15, 2024
In this issue of Trends, we provide several articles on energy and the environment.
Our first article discusses the complexity of PM2.5 toxicity and implications for further refinements to ambient air quality standards. The second article explores the growing demand for centralized data centers and potential implications for human health and the environment. The third article identifies the conflicting value and risk associated with carbon dioxide (CO2) capture technology. Our fourth article, adapted from a blog post authored by attorneys from Foley Hoag LLP, looks at efforts in Massachusetts and nationwide to streamline the permitting of large transmission line projects, including those related to clean energy.
Gradient contributors to this Trends issue include Nicholas Drury, Ph.D.; Naomi Slagowski, M.S.; Christopher DesAutels, M.S.; Ari Lewis, M.S.; and Tatiana Manidis, M.E.M.
Articles:
Gradient is presenting at PSX 2024, taking place October 15-17, 2024, in Denver, Colorado. See presentation details below.
Gradient’s PSX 2024 Presentations:
“8C: Analytical Methods for Microplastics and Nanoplastics and Potential Product Stewardship Applications”
Andrew Yeh, Kim Reynolds Reid, Matthew Tymchak (Moderator)
Education Session
Room: Aspen Ballroom
10/16/24 @ 11:00 am-12:00 pm
“10A: Supplier Ingredient Disclosure Challenges and Prop 65”
Kim Reynolds Reid
Express Session
Room: Mt. Sopris A
10/16/24 @ 3:00 pm-3:30 pm
Gradient Principal Lindsey Borton will be presenting at the North American Biocompatibility Summit (NABS) 2024, September 11, 2024 in Minneapolis, MN.
Gradient Senior Toxicologist Steven Boomhower will be presenting at EUROTOX 2024, September 8-11, 2024 in Copenhagen, Denmark.
US EPA Proposes to Extend TSCA PFAS Reporting Deadlines by Eight Months (January 11, 2026)
Citing funding difficulties delaying the development of the Toxic Substances Control Act (TSCA) section 8(a)(7) CDX reporting tool, the US Environmental Protection Agency (US EPA) is taking direct final action to change the start of the reporting period and reporting deadlines by eight months. This change, published September 5, 2024, will become effective in 60 days, unless US EPA receives adverse comments within the next 30 days.
Deadlines:
Beginning of Data Submission
November 12, 2024 (original); July 11, 2025 (amended)
End of Data Submission
May 8, 2025 (original); January 11, 2026 (amended)
End of Data Submission for Small Business, Article Importers
November 10, 2025 (original); July 11, 2026 (amended)
US EPA has also amended the requirement for submittal of environmental and health effects information in Organization for Economic Cooperation and Development Harmonised Templates (OHTs) for Reporting Test Summaries format from “each published study report” to “each unpublished study report.” Submittal of environmental and health effects information is only required for substances and mixtures, not for imported articles.
Link to the announcement in the Federal Register can be found here: Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) Data Reporting and Recordkeeping Under the Toxic Substances Control Act (TSCA); Change to Submission Period and Technical Correction
Gradient Experts:
Chase H. Butler, M.S.
Senior Environmental Chemist
Ari S. Lewis, M.S.
Principal
Caroline B. Tuit, Ph.D.
Principal
Jiaru Zhang, M.P.H., DABT
Principal Scientist
The California Department of Toxic Substances Control (DTSC) recently issued a notice of compliance approving the Preliminary Alternatives Analysis (AA) for motor vehicle tires containing the antiozonant N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine (6PPD), which was co-authored by Gradient scientists. 6PPD is an antiozonant used in motor vehicle tires sold worldwide and is critical to their safe use and longevity. Starting in 2021, scientific studies reported that a degradation product of 6PPD, found in tire and road wear particles, can cause pre-spawn mortality in certain sensitive fish species, particularly coho salmon native to the West Coast of the United States (US). The mechanism for this toxicity is currently unknown. At the request of the U.S. Tire Manufacturers Association (USTMA), DTSC listed motor vehicle tires containing 6PPD as a Priority Product under the Safer Consumer Products (SCP) program to facilitate the search for an acceptable 6PPD alternative. Over 70 candidate alternatives were evaluated in this robust process. As a result of the Stage 1 AA process, Gradient scientists identified seven possible 6PPD alternatives that warrant a deeper evaluation in terms of their performance and health effects:
The seven possible alternatives will now be evaluated in Stage 2, with the goal of identifying at least one replacement chemical with a better hazard profile and acceptable performance within two years. As part of the process, USTMA and Gradient scientists had detailed conversations with DTSC staff to help ensure that the submitted Preliminary AA could be approved by DTSC within the 30-day final review period. The Preliminary AA for 6PPD represents the third successful AA Gradient has prepared under the SCP program.
Gradient’s work was carried out on behalf of a global consortium of tire manufacturers mobilized by USTMA. A copy of the approved Preliminary AA is available on the USTMA website.
Gradient Experts:
Tom Lewandowski, Ph.D., DABT, ERT, ATS
Principal
Tom.Lewandowski@gradientcorp.com
Jiaru Zhang, M.P.H., DABT
Principal Scientist
Jiaru.Zhang@gradientcorp.com
Gradient Senior Epidemiologist Dr. Denali Boon will be presenting at the 36th Annual Conference of the International Society for Environmental Epidemiology (ISEE), August 25-28, 2024 in Santiago, Chile.
Gradient will exhibit at MEDevice Boston September 25-26, 2024, in booth number 523 (Exhibit Level Hall C).
Our team will co-present with Eurofins EAG Laboratories in the MEDevice Tech Theater at 10:30am ET on September 25.
Presentation Title: Biocompatibility Strategies for Saving Cost and Time When Making a Change to Your Device
Abstract: Material supplier and specification changes during initial and re-assessment of design verification biocompatibility activities can present an additional hurdle for manufacturers, which can result in costly and time-consuming retesting. In this presentation, we discuss how to evaluate biocompatibility material equivalence through leveraging physical and chemical characterization strategies. We incorporate ISO 10993-19 physical, morphological, and topographical (PMT) characterization to reduce the burden of retesting while ensuring enough information to evaluate device safety. Further, we will explain approaches leveraging targeted chemical characterization for equivalency and toxicological risk assessment of extractable chemicals.
Speakers include Drs. Alex Gauthier and Joel Cohen from Gradient and Drs. Todd Stark and Saheel Bhana from Eurofins EAG Laboratories.
View more information about our joint presentation or contact us to learn more about medical device services.
Gradient Senior Environmental Chemist Dr. Amy Hrdina will be presenting at the American Chemical Society (ACS) Fall 2024 conference, August 18-22, 2024 in Denver, CO & Hybrid.