EDF Health

21st Century on the horizon for endocrine disruptor screening?

By / Published: January 31, 2013

Rachel Shaffer is a research assistant. Jennifer McPartland, Ph.D., is a Health Scientist.

BPA, DDT, PCBs, PBDEs, phthalates, PFOA … Forgive the alphabet soup, but chances are you’ve heard of at least some of these endocrine-disrupting chemicals (EDCs), which have been the subject of a lot of public and media attention in the last several years. Research has begun to uncover the ways in which these chemicals can interact with the body’s hormone – or endocrine – system to disrupt various natural biological processes, including metabolism, the reproductive system, and development of the brain and nervous systems.

While the endocrine-disrupting properties of the chemicals named above have been confirmed, scientists suspect there may be many more such chemicals in our environment, in the products we use, and in our bodies.  How can we identify them?

Legislation enacted in 1996 required the U.S. Environmental Protection Agency (EPA) to develop a screening program to identify potential EDCs.  More than 10 years later, EPA finally launched the Endocrine Disruptor Screening Program (EDSP).  Testing is being conducted in two phases, or “tiers.”  In “Tier 1,” a screening battery of validated in vivo and in vitro assays is used to identify chemicals with potential to interfere with the endocrine system. Chemicals flagged in the first tier of testing are then subject to “Tier 2” testing intended to determine the specific effect and the lowest dose at which it occurs. (We should note this program is very controversial and the subject of ongoing debate, but that is not the subject of this post.)

EPA has identified an estimated 9,700 chemicals to be screened – a very daunting task given the time- and resource-intensive nature of the testing battery EPA has established.  Might there be a way to expedite the identification and testing of the more problematic chemicals? A study published earlier this year in Environmental Health Perspectives (EHP) investigates a possible approach: using in vitro high-throughput (HT) assays developed through EPA’s ToxCast and Tox21 programs to target and prioritize chemicals for further testing under the EDSP. While use of these assays poses its own challenges, might it at least help in determining an appropriate testing sequence?  Read More »

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Regrettable, if predictable: Bisphenol S mimics estrogen just like its better-studied cousin, bisphenol A

By / Published: January 17, 2013

Richard Denison, Ph.D., is a Senior Scientist.

A rule of thumb in chemistry is that chemicals that look alike will more often than not act alike.  (If it looks like a duck … .)  Indeed, when chemical companies are faced with testing requirements for one of their chemicals, they routinely argue that they should be allowed to submit test data on a structurally related chemical instead. 

So when it was revealed that companies making products (such as thermal receipt paper) that contain the estrogen-mimicking compound bisphenol A (BPA) were switching to another chemical called bisphenol S (BPS), many scientists’ eyebrows quickly arched.  Read More »

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Variety is the spice of … accurate chemical testing

By / Published: January 10, 2013

Rachel Shaffer is a research assistant.  Jennifer McPartland, Ph.D., is a Health Scientist.

There has been a lot of buzz in recent years about the federal government’s new chemical testing initiatives, ToxCast and Tox21 (see, for example, these articles in Scientific American and the New York Times).  These programs are developing high-throughput (HT) in-vitro testing to evaluate—and ultimately predict—the biological effects of chemicals.  In contrast to the relatively slow pace of traditional animal testing, ToxCast and Tox21 use sophisticated robots to rapidly test thousands of chemicals at a time. As a result, they hold the potential to more efficiently fill enormous gaps in available health data, predict adverse effects, and shed light on exactly how chemicals interact and interfere with our biology. (For more on these potential benefits, see Section 5 of EDF’s Chemical Testing Primer).

Yet, among the key challenges that these new methods must address is one that traditional, animal-based methods have faced for decades: how can laboratory testing adequately account for the high degree of variability in the human population? The latest research suggests the exciting possibility that genetic diversity, at least, may be able to be incorporated into emerging HT in vitro approaches.   Read More »

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TERA’s Kids+Chemical Safety website: On non-profits, objectivity and independence

By / Published: December 21, 2012

Richard Denison, Ph.D., is a Senior Scientist.

My recent post about the new American Chemistry Council (ACC)-sponsored website, Kids + Chemical Safety, engendered some comments that go directly to the issues of scientific objectivity and independence.

The website says “TERA [Toxicology Excellence for Risk Assessment, manager of the site] was founded on the belief that an independent non-profit organization can provide a unique function to protect human health by conducting scientific research and development on risk issues in a transparent and collaborative fashion and communicating the results widely.”  The “non-profit” descriptor – which TERA uses to describe itself no fewer than eight times on the site, including four times on this one page alone – seems intended to convey that TERA provides information that is purely objective and that it operates in a manner that is independent of who pays it to do its work.

It’s critical to recognize that being a non-profit does not conflate to, or somehow confer the right to claim, objectivity or independence.  The National Rifle Association is a non-profit that clearly has strongly held and expressed opinions.  EDF is also a non-profit, but I don’t pretend, as does TERA, that we don’t have a particular perspective and position.

So putting the issue of non-profit status entirely aside, we should judge TERA’s claim that its website provides information that is objective and independent based on its content, and that’s where it becomes quite clear that the information is neither.  Read More »

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Chemicals R Us: New ACC-sponsored website says chemicals are safe and fun for kids!

By / Published: December 19, 2012

Richard Denison, Ph.D., is a Senior Scientist.

[See also my more recent post on this topic here.]

I was alerted yesterday to a new website – kidschemicalsafety.org – funded by the American Chemistry Council (ACC) and run by its right-hand “non-profit,” TERA (Toxicology Excellence for Risk Assessment).  The website and an accompanying Facebook page are a wonder to behold, replete with photos of happy kids.  For the most part, I’ll leave it to you to explore.  But here are a few highlights.  Read More »

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EDF comments at EPA’s public stakeholder meeting on its IRIS Program

By / Published: November 14, 2012

Richard Denison, Ph.D., is a Senior Scientist.

I provide in this post the comments I delivered as a panelist at the Environmental Protection Agency’s (EPA’s) November 13, 2012 Public Stakeholder Meeting on its Integrated Risk Information System (IRIS) program.  EPA describes IRIS as “a human health assessment program that evaluates information on health effects that may result from exposure to environmental contaminants.”

 

The theme of my comments today is the critical need to restore balance to the IRIS program.  In my view, the program’s structure and practice have over time tilted badly toward allowing one set of interests and desirable attributes of chemical assessments to wholly dominate over another, equally critical set.  Let me explain.  Read More »

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