Lorenz R. Rhomberg, PhD, ATS, is the recipient of the Society of Toxicology (SOT) 2017 Arnold J. Lehman Award. During his career, he has made many contributions to risk assessment and the regulation of chemicals, which he accomplished through the development of sound scientific concepts and approaches to risk assessment for individual chemicals and hazardous situations.
He received his PhD in biology from the State University of New York (SUNY). In his early days as a risk assessor for the US Environmental Protection Agency (US EPA), one of Dr. Rhomberg’s first contributions was to suggest altering the parameters for a carcinogen dose-response model based on a set of equations and criteria including the Aikike Information Criterion (AIC). This led to an agency policy and software changes that became the standard for US EPA practices. He also provided leadership for conducting the agency’s first quantitative risk assessment using physiologically based pharmacokinetic models (PBPK) to estimate target tissue doses at different exposure levels, for different routes of exposure, and for cross-species dose equivalence evaluation.
As a result, Dr. Rhomberg led an Interagency Pharmacokinetics Group to review standard policies for cross-species extrapolation and addressed discordant assessments by establishing a common underlying rationale for cross-species extrapolation. Some years later, he was asked to apply the analysis to cross-species scaling of doses for non-cancer risk assessment, which became the policy on such methods.
While at the Harvard School of Public Health, Dr. Rhomberg’s work focused more fully on quantitative risk assessment, a probabilistic evaluation of uncertainties in non-cancer risk assessment in particular through specification and propagation of probability distributions for sources of uncertainty and variability. A Presidential/Congressional Commission on Risk Assessment and Risk Management asked Dr. Rhomberg to review the quantitative risk assessment methods for chemicals across the US federal agencies.
Currently, Dr. Rhomberg is a principal at the environmental consulting firm Gradient, LLC. At Gradient, he has been widely influential, contributing novel analyses and methodological approaches that advance toxicological risk assessment methodology. He established a framework for judging how different combinations of air concentration and exposure duration led to varying levels of acute toxicity. Most recently, “integration of evidence” (i.e., the problem of how rigorously, objectively, and transparently to combine inferences from sometimes contradictory information) has been Dr. Rhomberg’s focus. He formulated an approach called “hypothesis-based weight of evidence,” which stresses systematic evaluation of relevant studies seeking to bring to light hypothetical explanations for patterns found.
In addition, Dr. Rhomberg has advised European regulators as they develop evidence-integration methods, presenting his work to the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) and to the European Food Safety Agency (EFSA). Dr. Rhomberg continues to actively develop and codify science-based approaches to risk assessments relevant to today’s most important scientific issues.