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Two recurring themes at the 53rd meeting of the Society of Toxicology (SOT) in Phoenix, Arizona, were enhancing strategies for risk assessment and finding new ways to conduct safety assessments. Here are three questions (and some potential answers) that continue to drive the debate.
What are the biggest issues for the future of risk assessment?
Is there a need to change our current understanding (and approach) of exposure and acceptable doses?
Is there a need to change current approaches to integrating data?
I asked my fellow colleagues Dr. Robinan Gentry from ENVIRON® and Dr. Julie Goodman from Gradient®, both of whom led a session at this year’s SOT meeting, to share their thoughts.
According to Dr. Gentry, two key issues for improving the scientific basis of risk assessments are 1) improving the characterization of human exposure, and 2) adopting systematic approaches to data review and integration of weight of evidence into assessments.
“As risk assessors we need to determine whether and at what dose chemicals can cause health effects,” Dr. Julie Goodman adds. “Because scientific evidence is often inconsistent and incomplete, it is critical that it is evaluated in a systematic and unbiased manner.”
Dr. Gentry agrees there is a need to move away from “default approaches” to characterize exposure and determine which doses may be relevant to exposures humans are experiencing. By integrating biomonitoring data into current approaches and through a better understanding of kinetics data, Gentry says, risks assessors can improve their understanding of both target tissue levels and estimates of acceptable dose.
Risk assessors also face significant challenges with how to manage the sheer volume of incoming data and how to determine which are the most relevant to integrate into studies. “Our current approaches don’t easily lend themselves to integration of information for a given compound — much less across disciplines or sectors important for risk assessment,” according to Dr. Gentry. Developing systematic approaches may help alleviate the problem, but we are still left with the challenge of understanding the weight of the evidence for potential health effects, says Gentry.
So — what’s one of the leading problems with the way risk assessments are being done now?
According to Dr. Goodman, in evaluating studies, positive results are often given more weight than negative, regardless of study quality, making evidence seem stronger than it really is.
For weight-of-evidence evaluations to really work, however, they must be done in a transparent and systematic fashion, Dr. Goodman says. That means, for example, literature search terms and inclusion and exclusion criteria should be made explicit and relevant to the question at hand.
In addition, each individual study should be evaluated based on quality and relevance, not on the results, Goodman says. Studies of higher quality and greater relevance should be given more weight in the analysis, and evidence from disciplines like toxicology, epidemiology, and exposure science should be considered as a whole. In the end, Goodman says, this will allow us to make much more informed risk management decisions.
Many of these same issues were identified by a recent survey of toxicology experts conducted by George Mason University, which found widespread agreement on a need for the government to establish clearer policies and better methodology for conducting assessments.
ACC has helped to lead a constructive effort to improve the quality of federal chemical risk and hazard assessments. In fact, we just released a set of principles that are the outcome of numerous dialogues and stakeholder discussions, including those at SOT meetings, which have taken place over the past three years. We believe these principles will to help address ongoing issues and provide obtainable, high-level benchmarks for making assessment programs become more transparent, timelier, and ultimately more reliable as a decision-making tool to manage chemicals.
Dr. Robinan Gentry has over 25 years of experience in toxicological issues relevant in the determination of the potential safety or risk associated with exposure to chemicals in consumer products, pharmaceuticals or the environment.
Dr. Julie Goodman is a former Cancer Prevention Fellow at the National Cancer Institute and an expert in toxicology, epidemiology, and assessing human health risks from chemicals in consumer products and the environment. She also teaches a class on Research Synthesis & Meta-Analysis at the Harvard School of Public Health.
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