EDF Health

April brings showers…and a flurry of new studies on the risks of perfluorinated chemicals

By Rachel Shaffer / Published: April 30, 2013

Rachel Shaffer is a research assistant.

What do waterproof jackets, car wax, and non-stick pans have in common?

Aside from being great Father’s Day presents (Dad, I’m thinking ahead this year!), they also all are made with perfluorinated compounds, or PFCs. There are hundreds of different PFCs, and their oil- and water-resistant properties make them useful in a variety of products, from cookware and carpets to food-packaging and electronics.  

Unfortunately, these chemicals have less desirable properties as well. Thanks to their strong molecular bonds, PFCs do not readily break down; they persist in the environment and in our bodies. And, widespread use has led to extensive human exposure. The Centers for Disease Control’s (CDC) human biomonitoring program, the National Health and Nutrition Examination Survey (NHANES), detected four types of PFCs in over 98% of samples representative of the U.S. population collected in 2003-2004.  

Two of the compounds detected in NHANES, perfluorooctane sulfonic acid (PFOS) and perfluorootanoic acid (PFOA), are the focus of three new studies published this month in Environmental Health Perspectives. These studies, one reporting an association with osteoarthritis in women, another an association with semen quality in men, and a third an association with asthma in children, add to a growing concern about the potential adverse effects of these ubiquitous chemicals.

What follows is a brief overview of the findings of these new studies.  Read More »

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“Toxic Clout” shines a much-needed light on the chemical industry’s undue influence over toxic chemical decisions

By Rachel Shaffer / Published: March 25, 2013

Rachel Shaffer is a research assistant.

Remember the 2000 hit film, Erin Brockovich?  It was the Hollywood version of a real-life investigation into the contamination of groundwater in Hinkley, California with a known human carcinogen called hexavalent chromium (or hexchrome for short).  

Well, hexchrome is back on (a slightly smaller) screen, this time featured in a two-part series by the Center for Public Integrity (CPI) and PBS NewsHour.

The series, which aired on public TV stations earlier this month, highlights the continuing problem of hexchrome contamination around the country, including the still-unresolved situation in Hinkley.  Some 70 million Americans are exposed to this carcinogen through the water they drink. 

But the program also dives into another, even more concerning problem:  Years of delay in finalizing EPA’s risk assessment for the toxic metal, a prerequisite to any effective regulation.  Why the delay? Unfortunately, it’s an all-too-familiar story:  the chemical industry is stalling the process.  

And what are the consequences?  As EDF’s Senior Scientist Dr. Richard Denison says in the series:  “Decisions delayed are health protections denied.”  The chromium standard for drinking water has not been updated since 1991 and does not reflect recent scientific findings indicating that the standard needs to be significantly lowered to protect public health.

Check out the CPI/PBS segments (links below) and the related articles in CPI’s Toxic Clout series, which is part of an ongoing investigation of excessive industry influence in science and policy.

                Part 1: Science for Sale

                Part 2: Decision Delayed on Dangerous Chemical in Drinking Water

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21st Century on the horizon for endocrine disruptor screening?

By Rachel Shaffer / 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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Variety is the spice of … accurate chemical testing

By Rachel Shaffer / 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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