by Elizabeth Grossman
"If I say pollution, the images that first come to mind are likely to be smokestacks, waste pipes, an accident or a disaster. But increasingly, environmental health researchers are focusing on sources that are much closer to home, like toys and beauty products and food packaging and cleaners and furniture. These are now sources of chemicals of interest," said Julia Brody, director of the Silent Spring Institute introducing a session on biomonitoring at this year's American Association for the Advancement of Science annual meeting held recently in Washington, DC. "The measurement of pollutants in people and in places that are personal to them like their homes is really changing researchers' responsibilities to their study subjects and in turn are changing how we think of pollution," said Brody.
Biomonitoring, the measurement of environmentally available contaminants in human body fluids and tissue, is now a well-established technique for assessing chemical exposure levels. The Centers for Disease Control and Prevention (CDC) has been conducting biomonitoring studies for about thirty years. Biomonitoring is part of the CDC's National Health and Nutrition Examination Study (NHANES) and provides data for the CDC's National Report on Human Exposure to Environmental Chemicals (National Exposure Report). According to the CDC's most recent reporting, more than 300 "environmental chemicals" (including synthetic chemicals, heavy metals, volatile organic compounds, and over 200 industrial chemicals or their metabolites) are measured in human samples. Finding so many synthetic chemicals - substances that do not occur naturally - in the general public has opened up a whole new front in investigating pollution sources, chemical health effects - and ultimately in pollution prevention.
The AAAS session focused on the ethics and issues involved in sharing biomonitoring information with study subjects - how uncertainty about health effects of chemicals involved should influence what kind of information is shared; whether worry or stress caused by results should be taken into consideration and if so, how; and what kind of advice should accompany results.
But listening to the presentation I was struck by how occupational chemical exposures were absent from the discussion of environmental chemical exposures and by how, as we pay closer attention to previously poorly understood or overlooked sources of chemical exposure, workplace exposures are often left out of the conversation or are considered entirely separately. They are without a doubt important, though; according to OSHA, an estimated 60,000 deaths and 860,000 occupational illnesses per year in the U.S. are attributed to occupational exposure to chemicals.
Organizational and Technical Factors
When asked during the AAAS presentation about the limited attention to occupational exposures in biomonitoring studies, Shaun Goho, staff attorney with the Emmett Environmental Law and Policy clinic at Harvard Law School, began his response by saying that occupational exposures are taken care of by agencies that include OSHA and NIOSH. This is true, but occupational health regulations and statistics as currently configured are not effective at protecting against or accounting for illnesses with long latency periods that manifest themselves after workers have left the job where the chemical exposure occurred nor at handling exposures associated with reproductive health problems or birth defects that are difficult to pinpoint in a direct cause-and-effect scenario. Occupational health regulations are also not necessarily designed to protect against contaminants workers may bring home to their families on clothing.
Rachel Morello-Frosch, associate professor of Health at the University of California Berkeley, who presented to the AAAS audience the California-based "Chemicals in Our Bodies" study she's involved in, explained to me later by phone that a biomonitoring study's first goal is to measure a predetermined set of chemicals. For practical reasons of implementation, this kind of environmental monitoring test typically only measures what researchers have decided in advance to look for. Additional resources are required to trace the sources of chemicals detected. But, said Morello-Frosch, part of the study involves interviews and questionnaires to determine potential exposure sources for each study participant - what they may be encountering in the home, workplace, or elsewhere in their lives.
She readily acknowledged "a divide between how we consider consumer and occupational exposures." This divide is particularly visible in research and policies addressing pesticides, said Morello-Frosch. For example, she explained, the pesticide chlorpyrifos was phased out of consumer products about ten years ago but can still be used in commercial agriculture. This means that while people might be protected from being exposed through home and garden products, agricultural workers may still be exposed and may be sharing that exposure with their families. "We still see residues of chlorpyrifos in food, so the occupational exposures continue to effect consumers while occupational exposures continue," she explained.
For Workers, Limited Knowledge and Control
Amy Liebman, director of environmental and occupational health for the Migrant Clinicians Network, points out that researching consumer exposures - sources that an individual can choose to avoid - is undeniably important but tends to shift emphasis away from issues of environmental justice, which addresses exposures over which people have much less control. She too pointed to agriculture as an example of a particularly stark contrast in the consideration of consumer and occupational exposures.
Liebman explained that currently there are no federal requirements for individual personal exposure monitoring for agricultural workers. Under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), the EPA could - but does not currently - require companies that register pesticides for sale in the U.S. to conduct clinical tests to measure agricultural workers' exposures to their products. Biomonitoring exposure studies, she explained, would be an objective monitoring tool. She pointed out that in California and Washington where such requirements exist for certain pesticides, some growers have changed their practices - proactively reducing exposures.
Biomonitoring study results, regardless of any certainty of health effects, almost inevitably raise concerns about chemical exposures and have in many cases led to changes in the use of the products in question. A challenge in responding to biomonitoring study results, noted Morello-Frosch, is that people may have more ability to control chemicals in their home environment than that of their workplace. Workers who learn that their levels of workplace exposure are of concern may find it very difficult to convince their employers to improve exposure controls if no regulation explicitly requires them to do so.
Agriculture is far from the only industry in which workers know too little about what chemicals they're exposed to, let alone understand sufficiently their levels of exposure or potential health effects. What biomonitoring is teaching us about the ubiquity of chemical exposures, the multiplicity of potential sources of exposures, and actual levels of exposure has begun to change the formulation of many products, particularly those used in indoor and other home environments to eliminate hazardous chemicals (think cleaning and personal care products). Perhaps a greater use of occupationally focused biomonitoring could lead to similar improvements in workplace chemical use.
Elizabeth Grossman is the author of Chasing Molecules: Poisonous Products, Human Health, and the Promise of Green Chemistry, High Tech Trash: Digital Devices, Hidden Toxics, and Human Health, and other books. Her work has appeared in a variety of publications including Scientific American, Salon, The Washington Post, The Nation, Mother Jones, Grist, and the Huffington Post. Chasing Molecules was chosen by Booklist as one of the Top 10 Science & Technology Books of 2009 and won a 2010 Gold Nautilus Award for investigative journalism.
Thank you for your thoughtful blog. A couple of comments.
One of the problems regarding agricultural workers is that there are few clinical diagnostic tools to monitor workersâ exposures. We would very much like for chemical companies that register pesticides to provide (not conduct the actual tests) the clinical diagnostic tools so that workersâ exposures can be assessed.
Cholinesterase activity, a marker of overexposure to organophosphate and carbamate pesticides, offers the only easily available confirmatory test for pesticide poisoning, and this marker is nonspecific. Washington and California require cholinesterase biomonitoring for pesticide applicators. At a minimum we need a national emphasis for cholinesterase biomonitoring for pesticide applicators.
Please see the American Public Health Associationâs policy statement drafted by Matthew Keifer, MD, MPH and Amy K. Liebman, MPA on this topic. http://www.apha.org/advocacy/policy/policysearch/default.htm?id=1400
Amy ~ Thank you for clarifying the point about providing clinical diagnostic tools to conduct exposure monitoring and conducting the tests. It's an important distinction. But to clarify further, does providing clinical diagnostic tools mean funding tests or providing chemical-specific information that would guide accurate testing or monitoring for a specific pesticide?
I'd like to see some biomonitoring in office environments - all those synthetic fabrics, wall coverings, cleaners, printer inks, and last but not least, photocopy machines - not to mention how HVAC systems move chemicals & bacterial toxins throughout buildings.
APHA recommends that EPA require pesticide registrants, as a requirement for registration, to develop and provide to the publicâ
â¢ A sensitive and specific diagnostic test or biomonitoring tool to detect either chemical-specific levels in humans, the human health effects caused by their exposures, or both
â¢ A sensitive diagnostic test or biomonitoring tool to detect their chemical or its effects in human beings, the cost of which will be covered by the registrant