Poly- and Perfluoroalkyl Substances (PFAS): Environmental, Health, Ecological, and Regulatory Consulting

What are PFAS that seem to be in the news every day? They consist of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorobutanoic acid (PFBA), perfluorobutane sulfonate (PFBS), perfluorohexanoic acid (PFHxA), perfluorohexane sulfonate (PFHxS), and perfluorononanoic acid (PFNA), as well as GenX, ADONA, fluorotelomer alcohols (FTOH), and fluorotelomer sulfonates (FTS). These are the most commonly studied compounds of a large group of synthetic chemicals referred to as poly- and perfluoroalkyl substances (PFAS, formerly referred to as perfluorinated compounds, or PFCs). PFAS exhibit both oleophobic/lipophobic (oil/lipid-repellent) and hydrophobic (water-repellent) properties. In addition, they provide exceptional chemical and heat stability.

These unique and versatile properties have contributed to the use of individual and polymeric PFAS in a myriad of applications and products, including surface treatments and coatings for fibers (e.g., textiles, upholstery, carpets), leather, paper, food packaging, and cardboard products; aqueous film-forming foams (AFFF); mist suppressors in metal plating (e.g., chrome, copper, nickel, tin); industrial molding releases; and numerous consumer products (e.g., ski waxes, paints, personal care products).

The same useful properties for product and industrial applications, however, result in accumulation in organisms, including in humans, and environmental persistence. Scientific research into the potential environmental, health, and ecological impacts of PFAS, as well as the corresponding development and implementation of state and federal guidelines for PFAS control, has increased rapidly in recent years.
Exponent’s experts have experience in addressing the complex ecological, environmental, and health impacts of PFAS. Our broad capabilities in environmental fate and transport, health and ecological sciences, analytical and organic chemistry, regulatory consultation, and exposure and risk assessments support comprehensive PFAS investigations and analyses. We also have extensive experience in pharmacokinetic modeling and analysis; evaluation and interpretation of epidemiological, toxicological, environmental, and ecological data; environmental modeling; source identification; and the assessment of remediation strategies.

Exponent’s recent PFAS-related experience includes consultation on the following issues:

  • PFAS chemistry studies including chemical transformation(s), industrial and consumer applications, quantitative analysis, AFFF, and other product formulations
  • Potential health, environmental, and ecological effects of PFAS present in surface water, groundwater, sediments, soil, and air
  • Assessment of biomonitoring levels in humans and in the food chain, including pharmacokinetic modeling of exposure
  • State-of-the-science evaluations of the published literature on various health outcomes
  • Evaluation, validation, and statistical analysis of environmental and health data
  • Transport and fate of PFAS in various environmental media 
  • Standard of care in proper management of PFAS containing wastes
  • Natural Resource Damage Assessment (NRDA) of PFAS
  • Assessment of environmental liabilities and cost evaluations of proposed and implemented remedial strategies 
  • Comprehensive expertise in current regulations concerning PFAS in the United States (federal and state level) and internationally 
  • Comprehensive expertise regarding PFAS guidance of international health and environmental organizations
  • Consumer product evaluation for residual PFAS to support exposure and risk assessments
  • Critical evaluation and analysis of health effects studies related to PFAS for cancer and non-cancer endpoints.

Exponent Project Experience Overview

Environmental Transport and Fate, Hydrogeological Modeling, and Remediation of PFAS

  • Exponent has been engaged to evaluate the fate and transport of PFAS, including perfluoroalkyl acids (e.g., PFOA and PFOS), fluorotelomer sulfonates, and other polyfluorinated “precursor” compounds in environmental matrices such as groundwater, surface water, soil, sediment, and air. PFAS sources evaluated have included manufacturing sites, disposal sites, wastewater treatment plants, and other industrial and consumer sources (e.g., AFFF-impacted sites such as airports, chrome-plating facilities, pulp and paper mills, textile mills, tanneries, furniture manufacturing facilities, and aluminum sheeting production plants). 
  • Exponent experts have analyzed relevant data to document PFAS occurrence at sites of interest, reviewed and validated monitoring data, and developed fate and transport models to determine immediate and long-term impacts.
  • Exponent experts have assessed groundwater hydrogeology, reviewed existing groundwater models, and developed new models to evaluate PFAS transport under various potential environmental conditions and remedial options and to characterize the movement and behavior of contaminant plumes.
  • Exponent experts have evaluated the impact of closure of aquifers (sources of municipal drinking water) on the current status and potential future health and environmental effects of PFAS contamination.
  • Exponent experts have critically evaluated the selection, implementation, and outcome of proposed and existing PFAS remediation activities, including those for drinking water. 

Natural Resource Damage Assessment of PFAS

  • Exponent experts have evaluated the possible ecological impacts of PFAS in aquatic environments, including potential effects on aquatic and semi-aquatic animals. Using water, tissue, and sediment data, Exponent experts have assessed exposure potential and developed wildlife screening values for PFAS.
  • Exponent experts have reviewed and critiqued PFAS-related fish consumption advisories established by U.S. state regulatory agencies and assessed the validity of calculations used as a basis for such advisories.

Evaluation of Potential Impact of PFAS on Human Health

  • Exponent epidemiology and toxicology experts have assessed the results of PFAS biomonitoring studies conducted in the United States and internationally to evaluate human exposure to PFAS across time, geographic region, and demographic groups.
  • To evaluate exposure and risk assessments and health-based regulatory reference levels and limits for PFAS, Exponent toxicologists have used physiologically based pharmacokinetic modeling to evaluate relationships between PFAS exposure levels and internal doses. 
  • Exponent health scientists have conducted systematic reviews of the epidemiological, toxicological, and other relevant scientific literature on the potential exposure and human health risks of PFOA, PFOS, and other PFAS. These reviews have variously been published in peer-reviewed scientific journals, publicly released as comments on regulatory agency documents, and used as a basis for assessing whether PFAS exposure has causal adverse effects on human health.
  • Exponent health scientists have provided expert consultation on the toxicological and epidemiological science underlying a range of proposed regulatory guidelines for PFAS in the United States and other countries, including health advisory limits, human reference doses, drinking water limits, and fish consumption advisories. 

Assessment of Environmental Liabilities and Cost Evaluations of PFAS Remedial Strategies at Facilities Worldwide

  • Exponent scientists have developed estimates of remedial costs and liabilities associated with the use of AFFF at facilities worldwide where PFAS are anticipated to occur in the environment, particularly in groundwater. These analyses included assessment of the impact of prospective changes in regulatory threshold levels for some PFASs on estimated liabilities resulting from increased remediation costs.

PFAS Sampling and Analysis 

  • Through an understanding of PFAS chemistry, manufacturing methods, environmental and health issues, and exposure patterns, Exponent scientists and engineers have provided expert consultation on the complexities and analytical challenges associated with identifying and quantifying PFAS in different matrices and materials. Capabilities include selection of the appropriate matrices, analytical methods for quantifying individual PFAS compounds, and laboratories capable of these assessments. 
  • Exponent scientists have developed and implemented quality assurance project plans and sample analysis plans (QAPPs and SAPs) for collection of environmental and biological samples for measurement of PFAS compounds, including steps during sampling and analysis to prevent cross-contamination and ensure accurate quantification. Exponent scientists have also assessed the capabilities and methods of commercial laboratories for analyzing PFAS in environmental samples.

Expertise in U.S. and International Regulations, Rules, and Laws on PFAS 

  • Exponent scientists have expertise in PFAS regulations, guidelines, advisories, and laws in the United States and other countries. These include regulations proposed and implemented by U.S. federal and state agencies, the United Nations Environment Programme and the Stockholm Convention, the European Union, several European nations, and Australia.
  • Exponent scientists have provided expert consultation on how the inclusion of PFOA and PFOS on the California Proposition 65 list of reproductive toxicants will impact consumer products and processes.



News & Events