William (Bill) D. Klaren, Ph.D.
Senior Scientist


Phone(262) 806-3509
LocationAsheville, NC
Address31 College Place
Suite B118
Asheville, NC 28801

Professional Profile

Dr. William (Bill) Klaren is a toxicologist in ToxStrategies’ Health Sciences Practice. With a Ph.D. in Human Toxicology, and more than 5 years of experience across both academia and industry, he brings broad toxicological and risk assessment expertise to the consulting environment. Dr. Klaren has experience in systematic review and distilling essential concepts from published literature. Furthermore, he has expertise on the reliability and relevance of publications to advance prioritization initiatives. Dr. Klaren has also worked with mechanistic and in vivo data sets for subsequent incorporation into mode-of-action or adverse-outcome-pathway frameworks with a particular focus on endocrine disruption.

Dr. Klaren has performed numerous risk assessments on consumer products covering pest control and air care products, reviewed chemical portfolios, and overseen GLP acute toxicity testing. Additionally, he has supported exposure studies to refine risk assessments of consumer goods. This experience, coupled with an in-depth knowledge of regulations related to biocidal products, supported the registration of multiple pest control products in the US and EU. In conjunction with this support, Dr. Klaren has served on several task forces instituted to expand the robust safety profiles, through ongoing toxicity testing and governmental registrations, of the pyrethroid class of insecticides.

Dr. Klaren has expertise with new-approach methods (NAMs), highlighted by research into alternative approaches to animal testing by developing and qualifying high-throughput in vitro assays using organotypic cultures. By multiplexing the assays, many endpoints could be leveraged to generate bioactivity profiles for test substances. Such endpoints ranged from transcriptomics to cellular responses and morphology data. This approach was used for a wide variety of petroleum distillates, the prototypical UVCB (unknown, variable, complex, or biological substances), and provided a case study on the utility of such a framework in grouping similar biologically active substances. Dr. Klaren also conducted research into the degree of concordance between available in vitro assay data and DrugMatrix transcriptomic data, noting that key variables, such as physiochemical properties, can have a great impact on the magnitude of agreement between these orthogonal data sources—primarily demonstrating that context is key when understanding and using in vitro assay data.

Dr. Klaren has collaborated with academicians in the development of predictive models for endocrine disruption (ED) potential. This work encompassed all of the EATS (estrogen, androgen, thyroid, and steroidogenesis) modalities involving thorough evaluations of existing sources of endocrine related data, notably the ToxCast and Tox21 assay data. This work allowed for a preliminary evaluation of ED potential for data-poor chemicals found in consumer goods. Dr. Klaren has conducted ED potential assessments following current guidance, notably the ECHA/EFSA ED guidance, and has also conducted screening-level ED assessments on a variety of chemicals and components of consumer goods. He has advised decision-makers on the complexity of endocrine disruption toxicity and relevant regulations in pursuit of business goals and strategic decision making.

Dr. Klaren has a strong record of communication through publications and presentations. He is active in the Society of Toxicology, supports younger career toxicologists via guest lecturing, and has received multiple awards from employers and in academia.