Concerns about potential health risks associated with low-level exposures to PFAS, along with their widespread uses and reported detections in various environmental media and products, are triggering regulation, litigation, and an urgent need to apply the best available science in evaluating the exposure, toxicology, and epidemiology to characterize potential human health risks. ToxStrategies and EpidStrategies have extensive expertise and advanced technical resources to assist clients in navigating the scientific environment and growing regulatory labyrinth associated with PFAS.
ToxStrategies’ and EpidStrategies’ capabilities and experience include:
- Protocol development for PFAS extraction and migration from products, articles, and containers
- Assessment of fate and transport of PFAS
- Exposure and risk assessment of PFAS in environmental media
- Exposure and safety assessment of PFAS contained in a wide variety of products, including foods, packaging, personal care products, cosmetics, health and beauty care products, and commercial and industrial products
- In-depth knowledge of PFAS toxicology
- Expert witness and litigation support
- Development of PFAS toxicity criteria and toxicokinetic modeling
- Critical assessment and systematic reviews of PFAS epidemiological studies and evidence to understand impact on health outcomes
- Critical evaluation of current and proposed regulations to assess the epidemiological and toxicological underpinnings of existing and potential future guidance and standards
Our Capabilities
PFAS Source Identification
- Conditions of Use
- Source forensics
- Ambient PFAS data summaries
PFAS Chemistry and Analysis Support
- Sampling and Analysis Plans
- Product extraction and migration testing protocols
- Data Validation
- Statistical analysis of data
PFAS Transport and Fate Assessment
- Studies of PFAS migration from materials
- Environmental transport, transformation, and loss modeling
- Atmospheric dispersion and deposition modeling
- Plant and animal uptake, bioaccumulation, and bioconcentration
PFAS Exposure and Risk Assessment
- Knowledge of background (ambient) PFAS exposures and biomonitoring data
- Characterization of soil, groundwater, surface water, and air exposures
- Evaluation of ecological and human health risks
- Safety assessments of PFAS in consumer products, health and beauty care products, and foods
- Concentrations in articles of commerce
PFAS Toxicology and Toxicokinetics
- State-of-the-art knowledge of PFAS toxicity
- Development of PFAS toxicity criteria
- Threshold of Toxicological Concern (TTC) applications, QSAR and read-across studies, toxicity studies, transcriptomic analysis, mode of action (MOA) studies, PFAS low exposure risk thresholds, and evaluation of PFAS endocrine activity
- Physiologically Based Pharmacokinetic (PBPK) models
- Comprehensive literature reviews, systematic reviews, and risk-of-bias (RoB) analyses of the PFAS evidence base
PFAS Regulatory Support
- In-depth knowledge of state, federal, and international PFAS screening levels and their scientific bases
- Development of cleanup levels under state rules
- Prioritization of PFAS compounds
- TSCA Pre-manufacture Notice (PMN) preparation and toxicity testing
- Preparation of existing chemical risk evaluations under TSCA
PFAS Epidemiology
- Evidence-based assessment of the health effects of PFAS in humans based on identification and evaluation of epidemiological studies
- Epidemiological studies of community cohorts potentially exposed to PFAS
- Critical appraisal of epidemiological literature on PFAS exposure and health outcomes using established systematic literature review methods
- Qualitative and quantitative risk-of-bias and uncertainty assessments
Example Project #1: Develop PFAS Toxicity Criteria for Understudied Congeners
Most PFAS have little or no toxicity information, thereby necessitating a resource-effective approach to screening and prioritizing those needing further safety assessment. We developed toxicity criteria for PFAS applying a Threshold of Toxicological Concern (TTC) and deriving provisional chronic oral toxicity values (PCOTVs). The application of the TTC approach to PFAS was conducted by incorporating a dataset of no-observed-adverse-effect level (NOAEL) values for 28 PFAS into the corrected Munro TTC database. The PCOTVs were derived from 30-day animal studies using benchmark dose modeling. These methods allow for risk assessment of PFAS congeners that otherwise lack published toxicity thresholds.
Example Project #2: Evaluation of a Perfluorinated Acid in Carpet
To address potential concerns associated with exposures to perfluorooctanoic acid (PFOA) in carpet-related products, a comprehensive evaluation of PFOA literature was undertaken and included all published and unpublished chemistry, environmental exposure, pharmacokinetic, animal, human volunteer, and occupational studies. A 100+ page primer was developed for the client detailing the findings.
Example Project #3: Community Exposure Reconstruction: Historical Air Releases of PFOA from a Fluoropolymer Manufacturing Facility
ToxStrategies scientists conducted a historical exposure reconstruction of Ohio and West Virginia residents who were exposed to perfluorooctanoic acid (PFOA) via ambient air releases from a fluoropolymer manufacturing facility that operated in the area for 53 years. The retrospective exposure analysis required the estimation of historical releases to the environment using a mass-balance approach, followed by quantification of PFOA in various environmental media using air dispersion, soil, groundwater, and surface water models. The results of the analysis provided a picture of potential residential exposures to PFOA in the nearby communities across time.
Example Project #4: Development of an Oral Reference Dose for GenX
ToxStrategies developed a non‐cancer oral reference dose (RfD) for GenX based on repeated dose toxicity studies. Our experts evaluated potential modes of action and the relevance of specific toxicological effects. A combination of traditional frequentist benchmark dose models and Bayesian benchmark dose models were used to derive relevant points of departure from mammalian toxicity studies. In addition, deterministic and probabilistic RfD values were developed using available tools and regulatory guidance. These values were supported by numerous critical in vitro and in vivo mechanistic studies published by ToxStrategies on the MOA of GenX in rodents and by identifying mechanistic differences between rodents and humans.
Example Project #5: Exposure and Risk Assessment of PFAS Detected in Commercial and Consumer Products
ToxStrategies developed conditions of use and conceptual exposure models and modeled potential exposures from PFAS in several commercial and consumer products. The potential for unacceptable risk was determined by comparing the estimated exposures to toxicological points of departure (e.g., Margins of Exposure or MOEs), available regulatory screening levels, measured ambient PFAS levels, and measured levels of PFAS in other publicly and commercially available products.
Example Project #6: Expert Witness Support for a Defendant in PFAS Litigation
ToxStrategies prepared an expert report assessing the validity of plaintiff claims that the defendant caused significant PFAS contamination in groundwater and posed a health risk to the plaintiffs. A comprehensive risk assessment was conducted to compare the PFAS concentrations in drinking water to regulatory and non-regulatory risk levels on a congener-by-congener basis. Additionally, a state-of-the-art evaluation was conducted to determine the regulatory and scientific landscapes of PFAS knowledge from 1940 through the present. Deposition testimony was provided in support of the expert report.
Click link below for ToxStrategies’ PFAS publications