Christopher Scholosser

Christopher Schlosser

Managing Scientist
Chemical Regulation & Food Safety

Mr. Schlosser is a toxicologist with almost 10 years of experience in regulatory toxicology and risk assessment in the fields of pesticides, industrial chemicals, consumer products, and food safety. His primary focus is in the pesticide area, including conventional pesticides, biopesticides, and antimicrobials. Mr. Schlosser spent 6 years as a toxicologist and risk assessor with the Health Effects Division (HED) of the United States Environmental Protection Agency’s (US EPA) Office of Pesticide Programs (OPP). In this role, he served as co-chair for HED’s Toxicology Science Advisory Committee (ToxSAC) and Cancer Assessment Review Committee (CARC). Additionally, Mr. Schlosser was considered HED’s expert for dermal absorption issues on the ToxSAC. Due to his experience in pesticide regulation, Mr. Schlosser has developed a respected reputation and solid working relationship with both pesticide regulators and registrants and is skilled at working with both parties to develop innovative and strategic approaches to addressing human health concerns for pesticide registration. He is skilled at project management and effectively communicating with clients.

Mr. Schlosser has a comprehensive knowledge of toxicological regulatory requirements for pesticide active and inert registrations in the United States (including California’s Department of Pesticide Regulation (DPR)), Canada, and Europe, as well as a thorough understanding of the toxicological testing requirements and the differences in the intricacies of study interpretation amongst the different regions’ regulatory authorities. He is proficient in all areas of pesticide toxicology and addressing toxicological issues related to many aspects of pesticide registration including: new chemical registrations, new uses for existing registrations, and providing support for registration review and data-call ins (DCIs) on registered pesticides.

Mr. Schlosser conducts data gap analysis reviews of toxicology databases for pesticide active ingredients and pesticide inerts. Mr. Schlosser prepares study waiver documents (including significant experience with EPA’s waiver criteria for comparative thyroid assays) and bridging rationales to address toxicological testing requirements for pesticides based on the available toxicological database, structurally similar compounds, Quantitative Structure–Activity Relationship (QSAR) modeling, and risk evaluations. He prepares data evaluation reports (DERs) and OECD study summaries, as well as overall hazard characterizations based on all available toxicology data. Mr. Schlosser is highly skilled in selecting toxicological endpoints for human health risk assessment and identifying appropriate points of departure for risk assessment exposure scenarios. He also has experience determining if metabolites/degradates identified in residue chemistry or environmental fate studies are of toxicological concern for human health risk assessment. Mr. Schlosser provides technical support on carcinogenic effects observed in chronic toxicity studies and prepares toxicological Mode of Action (MoA) documents using the International Programme of Chemical Safety (IPCS) framework for cancer MoA submissions. Mr. Schlosser has experience reviewing studies and drafting weight of the evidence (WOE) documents for EPA’s Endocrine Disruptor Screening Program (EDSP). Mr. Schlosser designs and monitors toxicological studies to address guideline regulatory requirements, non-guideline regulatory agency DCIs, or other non-guideline studies with specific study design expertise in dermal absorption, neurotoxicity, and cancer MoA.

In his previous capacities outside of his role with the US EPA, Mr. Schlosser has held the position of Senior Toxicologist with an industrial chemical company and was responsible for developing and maintaining IUCLID dossiers for EU REACH chemical registrations, providing support on regulatory compliance issues for chemicals registered with the US EPA under FIFRA, and designing, contracting, and monitoring studies to address data gaps for both US and EU regulatory agencies. Mr. Schlosser also has previous consulting experience as an associate toxicologist for a toxicology and risk assessment consulting firm. In this role he provided hazard assessment support for identifying safer chemicals following EPA’s Safer Choice chemical program criteria. He was responsible for conducting hazard reviews of cosmetic ingredients and dietary supplements, as well as risk assessments on chemicals extracting from drinking water devices.


  • M.F.S., George Washington University
  • B.S., Chemistry, Illinois State University
  • B.S., Biochemistry & Molecular Biology, Illinois State University


Moser, V.C., Liu, Z., Schlosser, C., Spanogle, T.L., Chandrasekaran, A., and McDaniel, K.L. 2016. Locomotor Activity and Tissue Levels Following Acute Administration of Lambda- and Gamma- Cyhalothrin in Rats. Toxicology and Applied Pharmacology 313:97-103

Prior Experience

Senior Toxicologist, Nouryon 2019-2020

Toxicologist, EPA 2013-2019

Associate Toxicologist, ToxServices 2010-2013

Professional Affiliations

National Society of Toxicology (SOT), 2020 – present, Full Member

Project Experience

Toxicology lead for global submission of toxicology packages/dossiers for new active ingredients on conventional pesticides, biocides, and anti-microbials in the US (including California DPR), EU, and Canada.

Establishing NOAEL/LOAEL values for all toxicology studies required under FIFRA, selecting points of departure for all exposure scenarios, recommending cancer classifications, reduced risk applications, and tolerance petitions.

Several OECD Tier II summaries on all types toxicology studies for EU submission.

Several assessments of the mode of action and human relevance of thyroid tumors in rats including mechanistic study design and monitoring. Including risk-based assessments to address the need for comparative thyroid assays.

Mode of action and human relevance of liver tumors in mice and rats and lung tumors in mice using the IPCS Human Relevance Framework including mechanistic study design and monitoring.

Toxicological testing lead for North American biopesticide registration, including study design, placement and monitoring.

QSAR modeling conducted using DEREK and review of OECD Toolbox QSAR modeling in determination of toxicological relevance of impurity and metabolite of concern relevance for FIFRA registration.

Design and support of dermal triple pack testing (in vivo rat, in vitro rat and in vitro human) in support of deriving a refined dermal equivalent dose for pesticides.

Waivers from inhalation, immunotoxicity, and neurotoxicity testing requirements under FIFRA based on review and evaluation of toxicological database, review of similar compounds, and point of departure and margin of safety in dietary and occupational health risk assessments.

Review of toxicological databases to support establishing waiver criteria from long-term animal cancer bio-assays.

Human health toxicology reviewer of EPA’s Tier I Endocrine Disruptor Screening Program (ESDP) assays and weight-of-evidence documents.

Toxicology reviewer and contributor to EPA’s Guidance for Waiving Acute Dermal Toxicity Tests for Pesticide Products & Supporting Retrospective Analysis.

Review of dermal triple-pack data to support use of in-vitro human dermal absorption data for human health risk assessment.