A case-control study of exposure to organophosphate flame retardants and risk of thyroid cancer in women

Abstract

BackgroundGrowing evidence demonstrates that exposure to organophosphate flame retardants (PFRs) is widespread and that these chemicals can alter thyroid hormone regulation and function. We investigated the relationship between PFR exposure and thyroid cancer and whether individual or temporal factors predict PFR exposure.MethodsWe analyzed interview data and spot urine samples collected in 2010–2013 from 100 incident female, papillary thyroid cancer cases and 100 female controls of a Connecticut-based thyroid cancer case-control study. We measured urinary concentrations of six PFR metabolites with mass spectrometry. We estimated odds ratios (OR) and 95% confidence intervals (95% CI) for continuous and categories (low, medium, high) of concentrations of individual and summed metabolites, adjusting for potential confounders. We examined relationships between concentrations of PFR metabolites and individual characteristics (age, smoking status, alcohol consumption, body mass index [BMI], income, education) and temporal factors (season, year) using multiple linear regression analysis.ResultsNo PFRs were significantly associated with papillary thyroid cancer risk. Results remained null when stratified by microcarcinomas (tumor diameter ≤ 1 cm) and larger tumor sizes (> 1 cm). We observed higher urinary PFR concentrations with increasing BMI and in the summer season.ConclusionsUrinary PFR concentrations, measured at time of diagnosis, are not linked to increased risk of thyroid cancer. Investigations in a larger population or with repeated pre-diagnosis urinary biomarker measurements would provide additional insights into the relationship between PFR exposure and thyroid cancer risk.Electronic supplementary materialThe online version of this article (10.1186/s12885-018-4553-9) contains supplementary material, which is available to authorized users.

Recent biomonitoring reports on phosphate ester flame retardants: a short review

“…Other PEFRs metabolites were more rarely analyzed. Tert-butyl phenyl phenyl phosphate (tb-PPP) and bis(2-ethylhexyl) phosphate (BEHP) were detected infrequently (Su et al, 2015;Butt et al, 2016;Castorina et al, 2017b;Hoffman et al, 2017a;Soubri et al, 2017;Carignan et al, 2018a and b;Deziel et al, 2018;He et al, 2018a;Hoffman et al, 2018;Ingle et al, 2018;Sun et al, 2018). Dibenzyl phosphate (DBzP) was not detected in urine samples collected in the U.S.A. (Romano et al, 2017;Jayatilaka et al, 2017;Ospina et al, 2018).…”

“…This may be explained by differences in FR regulations, dietary habits, lifestyle, and use of PEFRs in household products and indoor environments (e.g., building material), between the various countries and/or study locations (Carignan et al, 2013;Butt et al, 2016;Lu et al, 2017;Chen et al, 2018;He et al, 2018b). Other factors were reported to have an impact on urinary PEFR metabolite concentrations, including timing (e.g., season of collection) (Hoffman et al, 2017a and b;Deziel et al, 2018;Ingle et al, 2018;Phillips et al, 2018), sex (e.g., women tend to have higher levels of DPHP than men, Hoffman et al, 2015b;Preston et al, 2017;He et al, 2018a;Ospina et al, 2018), behavior and activity patterns (e.g., hand washing and cleaning routines, nail painting) (Abdallah et al, 2016;Mendelsohn et al, 2016;He et al, 2018b) and age (Van den Lu et al, 2017;He et al, 2018a;Ospina et al, 2018;Sun et al, 2018). Urinary concentrations of the main PEFR metabolites were generally higher in toddlers than in adults (Butt et al, 2014 andCequier et al, 2015;Hoffman et al, 2015a;Van den Eede et al, 2015b;Chen et al, 2018;He et al, 2018a and b;Ospina et al, 2018).…”

Organophosphorus Flame Retardants: A Global Review of Indoor Contamination and Human Exposure in Europe and Epidemiological Evidence

“…A positive association was found between TPHP metabolite urinary concentrations and mean total thyroxine levels measured cross-sectionally in serum (T4 hormone, mainly secreted by the thyroid gland, and essential for proper metabolic functioning) among women, but not in men [67]. The TDCIPP urinary metabolite concentrations measured in women from a case-control study (100 cases and 100 controls) were not associated with an increased risk of papillary thyroid cancer [62]. The TCEP concentrations measured in house dust samples were associated with an increased risk of papillary thyroid cancer in women from a case-control study (70 cases and 70 controls) [65].…”

“…Since 2000, 19 epidemiological studies have been assessed, mostly in the USA, on the associations between exposure to OPFRs and health effects in humans, and they are presented in Table 1 [40,[58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74]. The health outcomes studied were reproductive, thyroid, neurodevelopmental, respiratory, immunotoxic and dermal.…”

Contemporary Debates in Adult Papillary Thyroid Cancer Management

“…Flame retardants -One small study suggests exposure to specific retardants increases thyroid cancer risk (50). Two other studies were negative for a flame retardant-thyroid cancer relationship, although assessed different flame retardants (51,52). Exposure to flame retardants has increased over time.…”