Carla Hustak had the opportunity to have a conversation with Canadian scientist, Derek Muir, an internationally recognized expert on the current environmental risks of endocrine-disrupting chemicals (EDCs). Muir was one of the authors of the most recent UN Report on the state of endocrine science. Since 1984, Muir has been investigating chemical contaminants in Canada. He has worked with Aboriginal Affairs and Northern Development Canada and has been involved in Arctic monitoring programs. Over the course of his impressive career as an environmental scientist, he has conducted specific studies on polar bears, seals, beluga whales, and fish as bio-indicators of levels of chemical exposures and environmental harm.
The interview with Muir was an enlightening experience, providing valuable insight into how scientists generate knowledge about endocrine-disrupting chemicals.We learned about the challenges of negotiating scientific practice with the objectives of policy-makers, agencies, and institutions in addition to the practical needs for funding scientific research. Muir also highlighted the geographical scope of endocrine science in terms of both specific Canadian sites of concern and our lack of knowledge of endocrine disruptors beyond North America and Europe.
Gathering Evidence, the Practice of Endocrine Science: What Do We Know About EDCs and Exposure in Canada
Muir and I began our discussion with his contributions to the UN Report on EDCs in collaboration with other world-leading experts on endocrine science. Muir explained that his specific role in the report involved “looking at trends in contaminants,” drawing on his familiarity with the literature from around the world on this subject. In the process of documenting what is known about EDCs, Muir highlighted how the gaps in our knowledge and what we do not yet know became startlingly apparent. He noted that “We took information from well-documented cases which are PCB trends and also DDT which is the best data available and put it in our report. In the course of doing this, we also identified that we were missing trends on exposures to many other chemicals.” According to Muir, the report therefore not only pointed out what we do know about EDCs but also what is in pressing need of further investigation; namely, the combined interaction of multiple endocrine-disrupting chemicals in the environment. This need points out another important trajectory in endocrine research which has tended to focus on the effects of a single chemical.
Muir shared with me the complications confronted by scientists in assessing safe thresholds of exposure to endocrine-disrupting chemicals which have the unique property of being potent at very low levels. Muir explained the difficulties in accurately measuring exposure, particularly in the problem of how to address multiple mixtures. The challenge involves dealing with some molecules that are more potent than others in one particular zone. Muir indicated the specific challenges with endocrine-disruptors:
“Estrogen is hard to measure in water or environmental media. It’s very potent at low levels. Some of the other chemicals are easier to measure. I’m not sure how regulators are treating them, if they are even at that stage. One of the big debates is how to regulate chemicals like this. They don’t fit nicely into being bio-accumulative. They are degradable. I’m thinking of the ones that cause feminization that look like estrogen in terms of molecular structure. And then there’s the issue that there are many other endocrine effects besides estrogenic; there is androgenic and effects on the thyroid.”
Both the difficulties of measuring as well as recognizing chemicals that deceptively mimic estrogen in their structure present unique challenges for gauging our vulnerability to these chemicals. Consequently, chemical exposure may be higher than current studies on single chemicals can suggest.
On the subject of multiple chemical interactions, Muir cited a study done by his former postdoctoral student, scientist Karen Kidd, on synthetic estrogen in the Experimental Lakes Area (Kidd et al PNAS 2007) and its interaction with other classes of chemicals. Muir pointed out that “there is this other story and other classes of chemicals that are more prevalent and harder to get rid of and they have very specific estrogenic effects such as feminization. So there are several stories within the whole big story from the chemical side.” The Great Lakes, in particular, have been a site of Muir’s work on endocrine-disruptors. Muir, working at Environment Canada’s Burlington Centre for Inland Waters noted that the Great Lakes is one of the “areas of concern that have been identified and if you go in there, the vulnerable populations are fish that are resident and often school around warm wastewater effluents.”
The Great Lakes has become an area of concentration for scientific research on chemical exposures. Muir, in fact, credited his colleagues at the Burlington Centre with being among Canadian scientists in the 1990s who did pioneering work on the feminization of fish in response to exposures to endocrine-disrupting chemicals from pulp and paper effluents. Addressing some of the challenges confronted by endocrine scientists grappling with the complexities and ambiguities of scientific work, Muir indicated that “they never identified what the chemistry there is. It’s just called pulp and paper effluent. Not that that’s a criticism, it’s just a challenge.” Muir further explained the initial stages on the road to arriving at the knowledge we have today of these chemicals: “At first, they thought the issue was dioxins, due to use of chlorine to bleach pulp, but, as it turned out, that didn’t explain the feminization. It’s more likely a series of other chemicals that are related to polycyclic aromatic hydrocarbons or PAHs.” As a result of this valuable work, “a whole program was developed, the Environmental Effects Monitoring Program, for pulp mills to monitor fish and water quality.” Muir compared the ambiguity of the phrase “pulp and paper effluent” to the phrase “oil and refinery effluent” in masking the complex chemistry of the effluents. Although the biological effects of oil and refinery effluent are different from pulp and paper, Muir noted that both have “certain toxics that can cause some sub-lethal effect which may be reproductive or endocrine.”
In addition to working in the Great Lakes, Muir has also been investigating environmental harm in the oil sands. Muir noted that “there is a lot of literature on PAHs [oil sands] being quite toxic. We can’t ignore PAHs because they don’t bio-accumulate but they’re all around us due to emissions from fuel combustion (for example).” Currently, Muir’s work on oil sands is pursuing a line of inquiry that did not get sufficiently addressed in the UN report; namely, geographical trends in PAH deposition. The extent of the geographical spread of contaminant effects raises the issue of what counts as a safe distance from a toxic site. According to Muir, his work is exploring whether “at this remote site are the levels high enough or is it a unique chemical that can still be high enough to create a certain exposure.” Interestingly, Muir pointed out that where an organism is situated in the food web can make a difference to exposure. There can be “low exposure in the low part of the food web but a unique animal [like the polar bear] that is eating the fat of seals or other tissues of seals gets very high exposures.”
Social Worlds of Endocrine Science: Policy-Making, Industry, and Funding Constraints
Muir informed me of the ways that scientists negotiate the geographical and institutional landscape of endocrine science. In particular, Muir emphasized the problem of attaining a global picture of endocrine science in light of the uneven geographical distribution in scientific studies on EDCs. Highlighting one of the limitations of the report, Muir claimed that “the group that was assembled was mainly European-oriented and so we were probably a little biased that way. If you look at the literature, especially for the toxicity of wildlife, Europe is the center of where this work has been done.” Muir concluded that “the story isn’t really a global story yet because of the limited amount of work.” As to why Europe might be leading this knowledge on EDC exposures, Muir cited the European Commission and its regulations as offering an important “framework for research, the Water Framework for example, has driven a lot of new and really good science.” In doing so, Muir suggested some of the conditions that can further endocrine research.
One of the challenges for scientists working with organizations lies in the constraints of the specific objectives or expectations of certain institutions and/or agencies. For example, Muir discussed the division between the World Health Organization (WHO) and the United Nations Environment Programme (UNEP). Although the UN Report on the State of Endocrine Science deals with both human and wildlife exposure, policies on these exposures are separated. The area of human exposure is relegated to the domain of WHO. In terms of maternal health programs that could result from this knowledge of endocrine disruptors, Muir indicated those initiatives would be addressed by WHO whereas UNEP focuses on its “mandate to raise awareness of endocrine disruptors around the world as part of the Strategic Approach on International Chemical Monitoring (SAICM).” Thus, in the very structure of UN agencies a separation is drawn between human and animal exposures even though scientists collaborating on the UN Report emphasize important linkages between them.
For Muir, one of the key tensions experienced by scientists in their relationships with industry, government, and other institutions is the demand for irrefutable evidence when the state of the science can only offer precautionary evidence. In terms of encounters with industry, Muir noted that “industry people typically want solid evidence before they want something banned. There’s always the tension between the precautionary approach and having irrefutable evidence.” He indicated that, for regulators, it is often not good enough to simply state “there’s the potential the effect of the exposure will never really be there.” Similar concerns also emerge in encounters between scientists and government policy-makers. When I asked Muir about the distinction scientists sometimes draw between their research and policy-making, he clarified policy as the “development of regulations would be the most obvious thing or providing information that reorients the government’s view internationally to chemicals.” There is a divergence between the interests of scientists and policy-makers for whom “the detailed science is typically not useful.” At Environment Canada in particular, “environmental chemists are very much into the Chemical Management Plan which is Health Canada’s main way of regulating chemicals.” Muir’s research did, in fact, directly contribute to policy-making back in the 1990s when Canada was leading negotiations of the Stockholm Convention. Muir reflected on being “in the right place at the right time with a lot of data, feeding it to people who were working at the policy level.”
In terms of the policy-making goals for the UN Report on EDCs, the UN ambition is to achieve the sound management of chemicals by the year 2020. Given the current state of endocrine science and the regulation of these chemicals, however, it is unlikely that this goal can be achieved. Muir pointed out that the important thing is the effort of “bringing people together” including regulators and the chemical industry in setting the 2020 goal. Although Muir confesses that he is not optimistic on that time frame, he notes the considerable strides that have been made in getting “places like China, Korea, and Taiwan creating chemical registries so they actually track the chemical production in the country. That’s new. That’s only happened in the last ten years and that’s part of the SAICM philosophy.”
In considering the science that has made such progress possible, some of the greatest debts are to the dedication of scientists, like Muir, who managed to attain the necessary funding to track chemical exposures over long periods of time. I would, therefore, agree with Muir that “the powerful stories in the report are where there are some sort of trend which means you have a dedicated person there. It’s often what you’re trying to do but if you can’t get further support then you have to move onto something else.”