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Claire M. Hamaji, MPH

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Claire M. Hamaji, MPH
Consultant

Claire M. Hamaji, MPH

Consultant (415) 458-6708 San Francisco, CA chamaji@integral-corp.com

Ms. Claire Hamaji is a dedicated human health risk assessor and regulatory toxicologist with 12 years of experience evaluating exposures to chemicals among consumers, workers, and the general public. As a scientist, she seeks to understand the nature and extent of human health risks presented by chemicals used in industry and commerce in order to inform better environmental policy from the local to national level.

Ms. Hamaji’s professional specialties include regulatory toxicology, quantitative human health risk assessment methods, and dermal exposure assessment. Over her career, she has amassed extensive experience managing and providing support on cases involving unique chemical exposures among populations that include industrial workers, consumers, children, and firefighters. Ms. Hamaji has assisted clients in navigating the requirements of Proposition 65, TSCA, per- and polyfluoroalkyl substances (PFAS) exposure limits, safe ingredient concentrations in personal care products, and more. Ms. Hamaji also has broad experience conducting human health risk assessments for contaminated sites. She has investigated exposures to a wide variety of chemicals, including heavy metals, bisphenol A (BPA), brominated flame retardants, PCBs, PFAS, perchloroethene (PCE), and wildfire smoke constituents. Her other scientific interests include science communication and advocating for gender equity within science.

May 2024 RSL Updates: Key Changes and Implications for 1-Methylnaphthalene

Resource

May 29 2024

Toxicology

Vinyl Chloride Toxicity, United States Managed and oversaw an evaluation of data gaps and data needs related to vinyl chloride toxicity to human and ecological receptors, as well as data availability regarding concentrations of vinyl chloride in environmental media. Communicated results to the client via written report to prepare them for conversations with EPA regarding the prioritization of vinyl chloride under TSCA.
Comments on IRIS Formaldehyde Assessment, United States Drafted comments on the draft Integrated Risk Information System (IRIS) assessment of formaldehyde for submission to the National Academy of Science, Engineering, and Medicine, and EPA. Developed critiques of the draft assessment's study selection for hazard identification and dose-response assessment, selection of critical effect levels for noncancer health effects, and consideration of mode of action in cancer dose-response assessment.
Evaluation of Chemical Exposure Parameters and Toxicity Values, United States Assessed peer-reviewed literature and toxicity databases to evaluate and critique chemical exposure parameters and toxicity values relevant to certain chemical classes, including alkylated PAHs and pharmaceuticals.

Human Health Risk Assessment

Proposition 65 Support, California Assisted clients in understanding their products’ standing under California’s Proposition 65 based on testing data, when available. Products evaluated include medical and personal use devices, crafting products, and more. Reviewed ingredient-specific toxicological information, identified relevant safe harbor levels, and ran exposure assessments to inform client business decisions.
Personal Care Products Ingredient and Product Safety Evaluations, United States Conducted and oversaw multiple evaluations for ingredient and product safety in the context of cosmetics, hair care products, and other personal care products. Reviewed ingredient-specific toxicological information and identified safe use levels for ingredients published by the Cosmetic Ingredient Review, Scientific Committee on Consumer Safety, Health Canada, and others. Conducted quantitative risk assessment where appropriate.
PFAS Exposure from Textiles, United States Ran refined risk assessment models simulating potential exposure to PFAS from textiles under different conditions of use using the latest science from the peer-reviewed literature on PFAS dermal absorption and migration from textiles. Communicated results to the client such that they understood the different iterations and the risk management implications of each risk assessment.
PFAS Human Health Risk Assessment, United States Led the development of a quantitative human health risk assessment characterizing potential noncancer risks from ingestion of PFAS chemicals in drinking water and home-grown produce among a residential community. Calculated expected PFAS exposures and refined risk calculations to reflect a variety of potential exposure scenarios.
Ethylene Oxide White Paper, United States Developed a white paper summarizing the state of the ethylene oxide (EtO) literature and commenting on EPA's EtO inhalation unit risk value. As project manager, increased efficiency by optimizing previously developed resources on EtO.
Occupational Exposure Factor Handbook, Dermal Pilot Chapter, United States Managed a project to develop a pilot chapter, focusing on dermal exposures, for an occupational exposure factors handbook intended to complement and inform EPA's risk characterizations under TSCA. Gathered and screened the most current and relevant resources on factors affecting occupational dermal exposure, and collated exposure factor data into a pilot chapter with accompanying commentary and context. Oversaw up to seven team members while communicating progress to internal experts and the client.
Risk Assessment for Exposure to Biocide, United States Conducted a quantitative risk assessment of potential irritation from dermal and inhalation exposures to a biocide among workers in a wood pressure treatment facility. Carefully reviewed the evidence regarding anticipated biocide exposure pathways and dose-response using industry reports and the peer-reviewed and government literature. Through the resulting report, the client was more informed regarding potential risks to workers at a typical wood pressure treatment facility and was able to identify potential controls for biocide exposure.
Risk Evaluations Critique, United States Provided ongoing support for chemical trade groups seeking guidance on navigating new and evolving EPA regulation under the reformed TSCA. Critiqued EPA risk evaluations for "first 10" chemicals and developed dermal sampling plans for clients in compliance with TSCA test orders and the latest science.
Mercury in Skin Whitening Products, United States As part of an ongoing manuscript, led a team of eight to conduct a survey of mercury concentrations in skin whitening products as reported in the peer-reviewed literature. Led the cleaning and analysis of mercury concentration data and conducted a probabilistic risk assessment to estimate the margin of safety for skin whitening product users, using the EPA reference dose for mercuric chloride as a health benchmark.
Risk Assessment of Formaldehyde Exposure among Funeral Home Workers, United States Oversaw quality control, data cleaning, and analysis of formaldehyde air concentrations collected during embalmings at 10 different funeral homes throughout the United States. Conducted a Monte Carlo probabilistic risk assessment to provide estimates of typical 8-hour time-weighted average exposures for embalmers.
PFOA in Drinking Water Guidelines, United States Collaborated on a manuscript to evaluate the basis and derivation of the existing state and federal health-based guidelines for perfluorooctanoic acid (PFOA) in drinking water. Researched state and federal guidelines for PFOA in drinking water, as well as the assumptions involved in the derivation of each guideline, including relative source contribution and drinking water intake rate.
Human Health Risk Assessment for Wildfire Smoke, United States Performed a comprehensive human health risk assessment for outdoor workers and residents exposed to wildfire smoke. Assessed the composition of wildfire smoke based on regional vegetation, selected constituents of potential concern, and calculated exposure concentrations based on data from the EPA Air Quality System.
Risk Assessments of Outdoor Workers following Wildfire, United States Utilized real-time data generated from air sensors installed at a retail distribution center to assess concentrations of carbon monoxide, nitrogen dioxide, ozone, fine particulate matter, and coarse particulate matter before, during, and after a wildfire. Compared site data to the Air Quality Index to draw conclusions regarding risks to outdoor workers following a wildfire.
Assessment of Draft Risk Evaluation for PCE, United States Critically assessed EPA's treatment of occupational data within its draft risk evaluation for PCE, and drafted comments to EPA with suggested alternative approaches to the data. Conducted an evaluation of the industry data used in the draft risk evaluation and proposed a refined approach to develop average and upper-bound exposure estimates for workers working with or around PCE, based on the nature and duration of worker tasks.
Michigan PBB Registry, Michigan Enlisted participants and maintained participant eligibility data for a multigenerational study investigating the potential epigenetic effects of exposures to polybrominated biphenyls (PBB) resulting from an industrial accident in Michigan during the 1970s. Screened attendees for eligibility for the Michigan PBB Registry's other ongoing epidemiological studies at biannual community meetings in Michigan. Conducted a spatial analysis of potential continued environmental exposures to PBBs among the Michigan PBB cohort, as part of a master's thesis. Employed ArcGIS software to visualize the distribution of Michigan PBB cohort members throughout Michigan and identified hot spots and cold spots of serum PBB levels. Identified potential clustering of elevated PBB serum levels among cohort members residing near the Velsicol chemical plant in St. Louis, Michigan.
Human Health Risk Assessments, United States Conducted human health risk assessments for industrial and commercial sites while communicating progress to principal risk assessors. Formulated conceptual site models, calculated exposure point concentrations using ProUCL software, calculated cancer risks and noncancer hazards for multiple human receptors, synthesized results into a written report, and addressed any client and regulator comments.
Risk Assessment Data Quality and Research Support, Walnut Creek, California Provided data quality support for numerous human health and ecological risk assessments and assisted in human health toxicology research.

Industrial Hygiene and Exposure Science

Evaluation of Proposed Trichloroethene ECELs, United States Developed comments regarding the technical feasibility of measuring trichloroethene (TCE) at levels commensurate with EPA's proposed existing chemicals exposure limits (ECEL) under the proposed risk management rule for TCE under TSCA. Consulted existing air monitoring methods for TCE as well as analytical laboratories to characterize not only the technical feasibility of measuring TCE at concentrations low enough to detect compliance with the ECELs, but also factors in the field and laboratory that may make air monitoring methods less sensitive.
Emissions Study of Semivolatile Chemical, United States Managed and oversaw the development of a pilot simulation study to characterize the emission rate of a semivolatile chemical from select consumer products, as mandated by an EPA test order under TSCA. Coordinated with testing facilities, designed a study plan, and coordinated communication with EPA throughout the study.
Dermal Sampling, United States Co-drafted a successful proposal outlining a dermal sampling project to evaluate solvent exposure among occupational cohorts.
Framework for Firefighter Dermal Exposures to PFAS, United States Developed the framework for a dermal sampling plan to assess firefighters' dermal exposure to PFAS from wearing turnout gear under conditions of extreme heat and humidity.
Lead-Based Paint Simulation Study, United States Led a team of five scientists on a successful proposal to conduct an internally funded simulation study characterizing potential release and exposure to lead in lead-based paint on a residential surface. Coordinated with the laboratory to plan artificial weathering of paint samples.
Occupational Exposure to Ethylene Dichloride, United States Compared industry occupational exposure data for ethylene dichloride (EDC) to EPA's proposed approach for its TSCA risk evaluation for EDC. Calculated EDC exposure statistics for different job titles based on industry-provided data, as well as EDC exposure statistics based on publicly available industrial hygiene reports. Compared estimated exposures for each job title based on the two data sets and communicated results to the client.
Development of Wildfire Air Quality Thresholds, United States Aided a major commercial distributor in determining internal air quality thresholds to prompt a reduction of work or work stoppage based on air quality conditions during and after wildfires. Utilized literature regarding health effects of wildfire smoke inhalation to balance the health of outdoor delivery workers with business operations.
Flame Retardant Concentration Review, United States Evaluated the temporal and spatial occurrence of multiple flame-retardant chemicals in a variety of indoor environments through a critical review of flame retardant concentrations in dust reported in the peer-reviewed literature.

Litigation Support

Support to Expert Witness in Personal Care Product Cases, United States Supported a testifying expert by reviewing ingredient-specific toxicological information and conducting quantitative risk assessments to determine whether the ingredient of interest was expected to induce skin sensitization under conditions of normal use. Risk assessment found that the ingredient of interest was not expected to induce skin sensitization given its concentration in the product and expected pattern of use.
Proposition 65 Litigation Support, United States Assisted a client in refuting claims of a Proposition 65 violation regarding excess dermal BPA exposure from use of a consumer product. Developed a dermal exposure model and ran the model using data generated from an Integral-conducted simulation study. This dermal exposure assessment was key to providing a favorable outcome for the client.    
Asbestos Litigation Projects, United States Managed up to 40 different asbestos litigation projects simultaneously for testifying experts. Staffed projects, trained and oversaw six team members, tracked budget, oversaw workflow, drafted technical reports, and communicated with the expert and client. Developed presentations for experts' deposition and appearance at trial, as needed.
PCB Exposure Assessments, United States Quantified exposures to PCBs at a school based on plaintiff testimony, records regarding building materials used at the school, and air sampling data collected from the school. Calculated daily inhalation exposures for each plaintiff and compared their exposures to regulatory exposure limits.
Childhood Lead Exposure Assessments, United States Reconstructed potential childhood lead exposures for plaintiffs residing in low-income communities. Evaluated the presence of lead in their homes using information provided in deposition testimony, lead paint and dust wipe sampling results, and knowledge regarding the fate and transport of lead in the environment. Assessed whether plaintiffs may have had complete lead exposure pathways, as well as whether any external sources of lead were present in their environment during childhood.

Sustainability

Sustainability Improvement, United States Compiled data regarding the sustainability of various remediation projects and identified primary sources of air pollution, as well as areas for future sustainable improvements.

Environmental Decision-Making

Fieldwork, United States Completed fieldwork duties, including compiling health and safety plans, collecting groundwater samples, and conducting biological surveys of California wetland species.

Groundwater Monitoring

Groundwater Monitoring Reports, Walnut Creek, California Generated and provided quality control for groundwater monitoring reports.

Lynch, H., L. Hallett, C. Hamaji, and A. Maier. 2023. Strategies for refinement of occupational inhalation exposure evaluation in the EPA TSCA risk evaluation process. Toxicol. Ind. Health 39(3):169–182.

Allen, L.H., C. Hamaji, H.L. Allen, G.H. Parker, J.S. Ennis, and M.L. Kreider. 2022. Assessment of formaldehyde exposures under contemporary embalming conditions in U.S. funeral homes. J. Occup. Environ. Hyg. 19(7):425–436.

Boles, C., R. Zisook, A.N. Buerger, C. Hamaji, C. Mathis, D. Lauer, R.K. Brewster, K.K. Meachum, M. Nonnenmann, and K.M. Unice. 2022. Semi-quantitative microbial risk assessment: A narrative review and proposed framework for health and safety practitioners. J. Public Health Emerg. 6:34. doi: 10.21037 /jphe-22-1.

Garnick, L., A. Massarsky, A. Mushnick, C. Hamaji, P. Scott, and A. Monnot. 2021. An evaluation of health-based federal and state PFOA drinking water guidelines in the United States. Sci. Total Environ. 761:144107.

Ierardi, A. M., C. Hamaji, A. Maier, and E. Fung. 2025. Comparison of three approaches to the derivation of acceptable surface limits for various chemicals. Poster presentation D231 at the Society of Toxicology 64th Annual Meeting, Orlando, FL. March 16–20.

Hamaji, C., C. Reagh, and E. Fung. 2025. A risk assessment of common aerosol hairspray ingredients and potential for systemic toxicity under home and salon use scenarios. Poster presentation L608 at the Society of Toxicology 64th Annual Meeting, Orlando, FL. March 16–20.

Hamaji, C. 2023. Finding Common Ground: Applied Lessons from the SOT Science Communications Training on How Empathetic Science Communication Can Make Science More Welcoming for All. Tiny Tox Talk presentation at the Society of Toxicology Annual Meeting & ToxExpo, Nashville, TN. March 19–23.

Hamaji, C.M. 2018. Investigating the Potential Multi-Generational Impact of Environmental Exposures on the Human Epigenome: Implications for the Southeast. Ramboll Environ. Atlanta, GA. October.

Ierardi, A.M., C. Hamaji, A. Maier, and E. Fung. 2025. Comparison of three approaches to the derivation of acceptable surface limits for various chemicals. Poster Presentation D231 at the Society of Toxicology 64th Annual Meeting, Orlando, FL. March 16–20.

Hamaji, C., C. Reagh, and E. Fung. 2025. A risk assessment of common aerosol hairspray ingredients and potential for systemic toxicity under home and salon use scenarios. Poster Presentation L608 at the Society of Toxicology 64th Annual Meeting, Orlando, FL. March 16–20.

Hamaji, C.M., L. Gloekler, H. Lynch, and A. Maier. 2023. A framework for optimizing dermal exposure assessment methods in occupational risk assessment. Poster Presentation P292 at the Society of Toxicology Annual Meeting & ToxExpo, Nashville, TN. March 19–23. Toxicologist 192(Sl):272. Abstract 3803.

Hamaji, C.M. 2022. A risk assessment of inorganic mercury renal toxicity from application of skin lightening products from multiple countries: An update. Society of Toxicology Annual Meeting. San Diego, CA. March 29.

Hamaji, C.M. 2021. A risk assessment of inorganic mercury renal toxicity from application of skin lightening products from multiple countries. Society of Toxicology Annual Meeting. March 22. Virtual.

Hamaji, C.M. 2019. Evaluating multi-generational impacts of PBB exposure in the Michigan PBB cohort. Emory University Rollins School of Public Health Outstanding Practicum Award Finalist Symposium. Atlanta, GA. April.

Hamaji, C.M. 2018. Investigating the potential multi-generational impact of environmental exposures on the human epigenome: Implications for the Southeast. 13th Annual Meeting of the Georgia Environmental Conference. Jekyll Island, GA. August.

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