Sunday, November 15th, 2009

Every day, we are exposed to a cocktail of synthetic chemicals from consumer products. How harmful are these? In an earlier post, I described how risk analysis is an important scientific process for determining exposure, effects, and overall risk of these chemicals.
One thing missing from these analyses is how people respond to information about their chemical exposure. In a recent issue1 of the Journal of Health and Social Behavior, Rebecca Altman and colleagues addressed this by analyzing what they call the “exposure experience” of women in Cape Cod, MA—an area with elevated breast cancer rates.
What did they find?
As part of a larger analysis (Silent Spring Institute’s Household Exposure Study), they measured 120 homes for 89 chemicals that could affect hormones. They also measured blood and urine concentrations in a sample of female residents.
They found that after receiving the chemical concentration data about their homes, participants concluded one or more of the following statements:
The response of many of the women included follow-up questions like
Altman and colleagues argued
In response to these circumstances, study participants reached out to others. As indicated in the previous excerpt, participants contacted the scientists, but they also queried friends and family (e.g., a friend with cancer, a daughter with a medical degree, or a son with scientific training). They shared study results with their physicians or oncologists. Some participants consulted Internet resources or local libraries. One participant copied the results for her landscaper, who had applied pesticides to her lawn and garden. Yet, as these participants reported, their friends and contacts—including their physicians—had few new insights to offer. Left unresolved were lingering questions: Participants’ narratives reflected puzzlement over how to interpret levels and make appropriate responses.
The research team noted that the participants were surprised by the number of chemicals detected in air and dust, and they weren’t sure where they could come from because the women perceived themselves using few chemicals. It turns out, as Altman’s team discovered, they were actually using several products containing these chemical, illustrating the disconnect between consumer culture an its associated chemical exposure risks.
Another trend: One of the first reactions of the participants was to attribute chemical levels to historical uses in the home, often citing the age of the home. But, again, this reflects the tendency to look for explanations beyond current consumption patterns.
They also found that participants may have underestimated the threat of chemical concentrations in their homes. When examining a graph showing the chemical concentrations in their home relative to all other participants’ homes and the EPA guideline level, many participants shrugged off their results as “average” when their home fell in the middle of the data values even when all of the data were above the EPA safety guideline. As Altman noted,
[f]or most participants, this perception of “average-ness” allayed concerns of health risk.
When the participants were concerned about the levels of chemicals in their homes, Altman argued that they sometimes fell victim to bad mental models of what to do:
Interestingly, when confronted with the notion that chemical levels remained high even after efforts to reduce them, several of the participants began controlling them symbolically, for example, by dissociating pesticides sprayed in the neighborhood with those found in their homes or bodies.
Bottom line:
One of the conclusions that Altman draws is that scientists conducting risk analyses need to think about the context/starting assumptions that people have regarding scientific exposure data. Specifically, it’s not enough for scientists to think about how to present uncertainty in the data; they also need to understand the “unique social and historical setting” in which the data are interpreted.
These stories make a compelling case that sociologists are (should be) an important part of the risk analysis process.
Related post: Do our daily routines put our health at risk?
1Altman, R. (2008) Pollution comes home and gets personal: Women’s experience of household chemical exposure. Journal of Health and Social Behavior 49(4): 417-435.
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Photo credit: http://www.flickr.com/photos/tzofia/ / CC BY-NC-ND 2.0