27 Feb Thyroid Hormone Disruptors Found In Household Cats and Dust
MedicalResearch.com Interview with:
Jana Weiss PhD
Department of Environmental Science and Analytical Chemistry
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: In an earlier publication, we could see an association between elevated concentrations of brominated flame retardants (BFR) in the blood of cats with developed Feline hyperthyroidism, compared to healthy cats (Norrgran et al 2015, ES&T 49:5107-5014). To establish the exposure pathway we now took paired samples from healthy cats and dust from their households. We also analysed the cats food to include another major exposure pathway. In total 17 families participated. They lived in houses in the countryside or in apartments in the city. All families had kids under 12 years of age living at home, thus representing a household with typical child products. The dust was sampled from the living room, the child’s room and from the adult’s bedrooms. We could not see any difference in the composition of compounds between the rooms, but we saw that levels were in general higher in the living room compared to the other two rooms. This was expected as many products being treated with BFRs can be found in the living room.
We could see that higher levels of some brominated flame retardants in the dust were correlated to elevated levels in the cat’s blood. Therefore, this hypothesized exposure pathways is now statistically established. We could also confirm cat food to be the major exposure pathway for naturally brominated compounds coming from the marine food web, such as6-OH-BDE47, a known thyroid hormone disruptor.
MedicalResearch.com: What should readers take away from your report?
Response: All households contained these compounds, which are leaking out from commercial products, such as furniture, textiles and electronics, where they are used to increase inflammability. All participating households had a mixture of the BFRs in their dust, and the compounds were also found in the blood serum of all cats. We could measure both classes of BFRs being phased out decades ago, the persistent ones, and the ones that are currently in use. This study shows that we are all exposed to brominated flame retardants, which are known hormone disruptors in animal studies.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: We need to continue the search for hormone disruptors in our household environment. We are currently looking for other thyroid hormone disruptors in the dust samples by applying a combination of bioassay and chemical analysis. We will find more health consequences from this exposure in the future. The chronic exposure to mothers, fetuses and children during sensitive developmental stages up to puberty can have serious consequences at the population level. The increased incidence of endocrine-linked disorders such as diabetes, obesity and learning deficiency is possibly due to a combination of exposure to hormone disruptors and other confounding factors such as lifestyle, physical activity and socioeconomic status.
MedicalResearch.com: Is there anything else you would like to add?
Response: The results reported in the article are part of a larger project called MiSSE (Mixture assessment of endocrine disrupting compounds. http://www.aces.su.se/misse/) were we specifically analyze for thyroid hormone disrupting compounds in our indoor environment. Next step in the project is to test mixtures of the compounds we have found in household dust using in vitro assays. We assume that ‘concentration addition’ can be applied, meaning that all compounds that disrupt thyroid hormone levels can add together to induce the total potency in the bioassay, including compounds that would be too low to have an effect on their own. In classical toxicological evaluations, concentrations below threshold values are considered to have zero potency in the assay (‘independent action’). It is time to challange that viewpoint and aid the risk assessors to treat the chemical mixtures more accurately, assessing not one compound in isolation, but considering the cumulative contribution from all the chemicals we are exposed to.
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Citation: J. Norrgran Engdahl, A. Bignert, B. Jones, I. Athanassiadis, Å. Bergman, J. M. Weiss. Cats’ Internal Exposure to Selected Brominated Flame Retardants and Organochlorines Correlated to House Dust and Cat Food. Environmental Science & Technology, 2017; DOI: 10.1021/acs.est.6b05025
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