Toxicity Translations

Final thoughts on the SETAC endocrine disruption meeting
by Abigail McEwen -- April 14th, 2014

Thoughts on day 3 and the overall experience as I wrap up my series of posts on the Society of Environmental Toxicology and Chemistry (SETAC) focused topic meeting on endocrine disruption! Check out my introduction and recap of days 1 & 2.

Some quick context: last month I attended a conference focused on chemical testing, risk assessment approaches, and implications of endocrine disruption. For those who are not familiar with this topic, the term ‘endocrine’ refers to the endocrine system, which can be thought of as the hormone system. Hormones are chemical messengers that control all biological functions within the body. Endocrine disruption is particularly concerned with androgen and estrogen hormones, which control male and female sexual development, and thyroid hormones, which control growth, reproduction, development, and metabolism. The term “disruption” refers to the ability of foreign chemicals (of both natural and synthetic origin) to enter the human body and alter the natural cycling of these hormones. For a thorough explanation, check out this US EPA site.

Day 3: more speaker sessions and an audience discussion

The final day of the conference was split into two speaker sessions. Continuing from the previous day, Session 4 was focused around hazard and risk assessment. As I mentioned in my previous post, there is no globally recognized system for assessing chemical safety to guide regulatory policy. In the United States, regulation is based on risk assessment, which evaluates both the hazard (or toxic nature) of a chemical as well as the exposure pathways and potential. In the European Union, regulation is currently based on hazard only assessment.

Under the latter conditions, a chemical can be banned from the market if it is shown to have significant negative effects on human health and/or the environment. However, this same chemical may still be permitted for use in the United States if the exposure potential is low. The reasoning behind this is that adverse effects can not occur if exposure does not occur. Based on the lectures and audience comments, it felt as though many attendees support the risk assessment based approach over the hazard based approach.

The final session presented challenges and future directions for testing methods. A major focus in this area is the development of “high-throughput” methods for screening and prioritizing chemicals. This type of technology runs chemicals through a suite of cell and protein tests to assess changes in biological activity that may indicate toxicity. While this provides a crude estimate of actual effects, it is an efficient and cost effective way to identify chemicals that may need more comprehensive testing.

The EPA has developed a high-throughput screening tool called ToxCast. This program is being used to prioritize chemicals for the Endocrine Disruptor Screening Program tier 1 assays.

This is important because there are thousands of chemicals on the market that have not been tested for adverse effects such as endocrine disruption. Kind of scary when you think about it! Even with full cooperation, it would take years to test this backlog of chemicals. And meanwhile, hundreds of new chemicals come on the market every year. At this point, these computational tools are really the only hope we have to assess the safety of chemicals in commerce.

After a quick coffee break, the final activity of the conference was an audience discussion. The goal of this was to produce an outreach statement for regulators and the general public. The conference attendees that participated in this discussion emphasized the need for this statement to define terms such as “risk”, address perceptions of risk and hazard assessment, and evaluate the current testing methods. I look forward to seeing SETAC release this statement soon.

And with the end of the discussion, I had successfully survived my first conference!

Overall, it was an enjoying and intellectually stimulating experience. It provided me with some much needed perspective on chemical regulation and testing, inspired me to think critically about my master’s project, and left with lots of questions to research (and blog about!). 

Before I finish this post, I want to thank the Career and Professional Development Center at the Nicholas School of the Environment for providing me with funding to attend this meeting. Conferences provide a truly unique platform to learn and network with experts and professionals, but they are not cheap to attend. All current and future Nich students should take advantage of this resource!

Tired of endocrine disruption talk? Coming up soon on Toxicity Translations… sustainability perspectives from Sweden and some thoughts on TSCA reform. 

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