Skewed distribution of hypothyroidism in the coastal communities of Newfoundland, Canada

Polybrominated Diphenyl Ethers (PBDEs) in Marine Fish and Dietary Exposure in Newfoundland

Presence of PBDEs tested in 127 liver samples from Atlantic Cod (Gadus morhua) and Turbot (Scophthalmus Maximus) and 80 adult participants from two rural Newfoundland communities. Seafood consumption was measured through a validated seafood consumption questionnaire. PBDEs (-28, -47, -99, -156, and -209) were found in all fish liver samples, and PBB-153 and PBDEs-28, -47, -99, -100, -153 were identified as the most prominent congeners from the participants' serum samples. Cod was the most frequently consumed species in the seafood consumption survey. PBB-153 was higher amongst older (> 50 years age) participants (p < 0.0001), however, no PBDE congeners were significantly different by age. PBB-153 (p = 0.001), PBDE-153 (p = 0.006), and ₅PBDE (p = 0.008) levels were significantly higher in males. The study shows that the marine ecosystem around Newfoundland has been contaminated by PBDEs, and that rural coastal residents are potentially exposed to these contaminants through local seafood consumption.

Fish and the Thyroid: A Janus Bifrons Relationship Caused by Pollutants and the Omega-3 Polyunsaturated Fatty Acids

Benefits of the omega-3 polyunsaturated fatty acids (PUFA) on a number of clinical disorders, including autoimmune diseases, are widely reported in the literature. One major dietary source of PUFA are fish, particularly the small oily fish, like anchovy, sardine, mackerel and others. Unfortunately, fish (particularly the large, top-predator fish like swordfish) are also a source of pollutants, including the heavy metals. One relevant heavy metal is mercury, a known environmental trigger of autoimmunity that is measurable inside the thyroid. There are a number of interactions between the omega-3 PUFA and thyroid hormones, even at the level of the thyroid hormone transport proteins. Concerning the mechanisms behind the protection from/amelioration of autoimmune diseases, including thyroiditis, that are caused by the omega-3 PUFA, one can be the decreased production of chemokines, a decrease that was reported in the literature for other nutraceuticals. Recent studies point also to the involvement of resolvins. The intracellular increase in resolvins is associated with the tissue protection from inflammation that was observed in experimental animals after coadministration of omega-3 PUFA and thyroid hormone. After having presented data on fish consumption at the beginning, we conclude our review by presenting data on the market of the dietary supplements/nutraceuticals. The global omega-3 products market was valued at USD 2.10 billion in 2020, and was projected to go up at a compound annual growth rate of 7.8% from 2020 to 2028. Among supplements, fish oils, which are derived mainly from anchovies, are considered the best and generally safest source of omega-3. Taking into account (i) the anti-autoimmunity and anti-cancer properties of the omega-3 PUFA, (ii) the increasing incidence of both autoimmune thyroiditis and thyroid cancer worldwide, (iii) the predisposing role for thyroid cancer exerted by autoimmune thyroiditis, and (iv) the risk for developing metabolic and cardiovascular disorders conferred by both elevated/trendwise elevated serum TSH levels and thyroid autoimmunity, then there is enough rationale for the omega-3 PUFA as measures to contrast the appearance and/or duration of Hashimoto's thyroiditis as well as to correct the slightly elevated serum TSH levels of subclinical hypothyroidism.

High Thyroid Cancer Incidence Rate in a Community near a Landfill: A Descriptive Epidemiological Assessment

Background: to investigate the high thyroid cancer incidence rate of Staten Island and to disentangle the effects of potential environmental exposure from a landfill from screening. Methods: age-adjusted thyroid cancer incidence rates obtained from the New York State Public Access Cancer Epidemiology Data for New York State (NYS) excluding New York City (NYC) and the five NYC boroughs, including Staten Island, were mapped over time (1995–2018), investigated per age group and by percentage of localized thyroid cancer. Changes in trends were assessed using joinpoint. Contaminants of concern on Staten Island were assessed for carcinogenic and endocrine disruptive properties. Results: a more pronounced thyroid cancer incidence rate increase, without a difference in age distribution and similar percentages of localized thyroid cancer, was found in Staten Island compared to its demographic equivalent (NYS excluding NYC). Multiple contaminants of concern with carcinogenic and endocrine disrupting properties (e.g., cadmium, lead) were identified in air, water and sediment samples. Conclusion: investigations into the effects of increased/sustained environmental exposures are needed in chronically exposed populations to identify potential mechanisms of action of certain pollutants.

Evaluating the use of synchrotron X-ray spectroscopy in investigating brominated flame retardants in indoor dust

Brominated flame retardants (BFRs) are commonly used in consumer products and they shed off these products and eventually build up in household dust. Polybrominated diphenyl ethers (PBDEs), in particular, are known endocrine-disrupting chemicals affecting various hormone syntheses. Portable X-ray fluorescence spectroscopy (XRF) is the most common non-destructive method in identifying BFRs in environmental samples. However, the method is insensitive to bromine speciation. Synchrotron-based XRF has been shown to have very low detection limits (< 1 μg/g) that is suitable for detecting BFRs and can be combined with X-ray absorption near-edge spectroscopy (XANES) to identify the bromine species present in the household dust. Twenty indoor dust samples were collected from rural homes in Newfoundland (Canada) to assess the use of synchrotron-based techniques to identify BFRs. Synchrotron-based XRF analysis identified bromine in all the samples, with concentrations ranging from 2-19 μg/g. XANES analysis identified organic-based bromine species in several samples that are likely BFRs based on the spectral line shape. The accuracy of using XANES to identify BFRs is highly dependent on the source and size of the dust samples. Therefore, for future research, it is important to take into account the sources of dust sample and to focus on fine dust particles.

Para-Dichlorobenzene Exposure Is Associated with Thyroid Dysfunction in US Adolescents

OBJECTIVE

To examine the association between exposure to para-dichlorobenzene, measured as urinary concentrations of 2,5-dichlorophenol (2,5-DCP), and thyroid function in US adolescents.

STUDY DESIGN

A nationally representative subsample of 618 adolescents aged 12-19 years in the 2007-2008 and 2011-2012 National Health and Nutrition Examination Survey was analyzed for the association of urinary 2,5-DCP with serum thyroid function measures using multivariate logistic and general linear regression models.

RESULTS

After adjusting for potential confounders, we found a significantly positive association between urinary concentrations of 2,5-DCP and serum levels of thyroid-stimulating hormone and thyroglobulin in adolescents. Furthermore, urinary 2,5-DCP was associated with an increased prevalence of hypothyroidism in the study population.

CONCLUSIONS

This study demonstrates a potential relationship between para-dichlorobenzene exposure, measured as urinary 2,5-DCP, and thyroid dysfunction in adolescents; however, further studies are needed to confirm our findings and to elucidate mechanisms of action.

Thyroid nodules and thyroid autoimmunity in the context of environmental pollution

Evidence suggests that in most industrialized countries autoimmune disorders, including chronic lymphocytic thyroiditis, are increasing. This increase parallels the one regarding differentiated thyroid cancer, the increment of which is mainly due to the papillary histotype. A number of studies have pointed to an association between chronic lymphocytic thyroiditis and differentiated thyroid cancer. The upward trend of these two thyroid diseases is sustained by certain environmental factors, such as polluting substances acting as endocrine disrupting chemicals. Herein we will review the experimental and clinical literature that highlights the effects of environmental and occupational exposure to polluting chemicals in the development of autoimmune thyroid disease or differentiated thyroid cancer. Stakeholders, starting from policymarkers, should become more sensitive to the consequences for the thyroid resulting from exposure to EDC. Indeed, the economic burden resulting from such consequences has not been quantified thus far.