Exposure to Perchlorate in Lactating Women and Its Associations With Newborn Thyroid Stimulating Hormone

Effects of perchlorate, nitrate, and thiocyanate exposures on serum total testosterone in children and adolescents

Perchlorate, nitrate, and thiocyanate are common thyroid disruptors in daily life and alter testosterone levels in animals. However, little is known about the effects of perchlorate, nitrate, and thiocyanate on serum total testosterone (TT) in the general population. The study was designed to assess the associations between urinary levels of perchlorate, nitrate, and thiocyanate and serum total testosterone (TT) in the general population. The present study utilized data from the 2011-2016 National Health and Nutritional Examination Survey (NHANES). A total of 6201 participants aged 6-79 with information on urinary perchlorate, nitrate, thiocyanate, and serum total testosterone were included. We conducted multiple linear regression models and Bayesian Kernel Machine Regression (BKMR) models to estimate the associations by sex-age groups. Children (ages 6-11) have higher levels of perchlorate and nitrate than the rest. After adjusting for covariates, urinary perchlorate was significantly negatively associated with serum TT in male adolescents (β = -0.1, 95 % confidence interval: -0.2, -0.01) and female children [-0.13, (-0.21, -0.05)]. Urinary nitrate was significantly negatively associated with serum TT in female children, while urinary thiocyanate was significantly positively associated with serum TT in female adults aged 20 to 49 [0.05 (0.02, 0.08)]. BKMR analysis indicated that no other interactions were found between urinary perchlorate, nitrate, and thiocyanate. Our findings suggested that urinary perchlorate, nitrate, and thiocyanate levels may relate to serum total testosterone levels in specific sex-age groups. We identified male adolescents and female children as are most sensitive subgroups where testosterone is susceptible to interference.

A newly developed consortium with a highly efficient thiocyanate degradation capacity: A comprehensive investigation of the degradation and detoxification potential

Thiocyanate-containing wastewater harms ecosystems and can cause serious damage to animals and plants, so it is urgent to treat it effectively. In this study, a new efficient thiocyanate-degrading consortium was developed and its degradation characteristics were studied. It was found that up to 154.64 mM thiocyanate could be completely degraded by this consortium over 6 days of incubation, with a maximum degradation rate of 1.53 mM h^-1. High-throughput sequencing analysis showed that Thiobacillus (77.78%) was the predominant thiocyanate-degrading bacterial genus. Plant toxicology tests showed that the germination index of mung bean and rice seeds cultured with media obtained after thiocyanate degradation by the consortium increased by 94% and 84.83%, respectively, compared with the control group without thiocyanate degradation. Cytotoxicity tests showed that thiocyanate without degradation significantly decreased the Neuro-2a cell activity and mitochondrial membrane potential; induced reactive oxygen species generation and apoptosis; increased the cellular Ca²⁺ concentration; and damaged the cell nucleus and DNA. Furthermore, the thiocyanate degradation products produced the consortium were almost totally non-toxic, revealing the same characteristics as those of the control using distilled water. This study shows that the consortium has a high degradation efficiency and detoxification characteristics, as well as great application potential in bioremediation of industrial thiocyanate-containing wastewater.

Concurrent dietary intake to nitrate, thiocyanate, and perchlorate is negatively associated with hypertension in adults in the USA

We aimed to comprehensively evaluate the association of urinary nitrate, thiocyanate, and perchlorate metabolites with hypertension among a nationally representative sample of the US adult population. This cross-sectional study investigated data from 15,717 adults aged more than 20 years obtained from the National Health and Nutritional Examination Survey (NHANES) for the years 2005-2016. In the survey, urinary levels of nitrate, thiocyanate, and perchlorate were measured using ion chromatography combined with electrospray tandem mass spectrometry. Blood pressure was calculated as the mean of three measurements. Hypertension was defined as (a) systolic BP ≥130 and/or diastolic BP ≥80 mmHg and/or (b) self-report. Multivariate logistic regression and weighted quantile sum (WQS) regression models were applied to estimate the association between exposure to multiple inorganic anions and hypertension. Restricted cubic spline (RCS) regressions were fitted to discern the potential relationship between the anion exposure and hypertension. These innovation methods used to support our results. Overall, 7533 (49.95%) people with and 7638 (50.35%) without hypertension were included in this study. In the multivariable-adjusted logistic regression models, urinary nitrate (P < 0.001) and perchlorate (P < 0.001) were independently negatively associated with increased occurrence of hypertension, while urinary thiocyanate was insignificantly associated with hypertension (P = 0.664). The WQS regression index showed that, in combination, the three inorganic anions mixture were negatively correlated with hypertension (adjusted OR 0.89; 95% CI 0.83-0.95, P < 0.001). Urinary nitrate was the most heavily weighted component in the hypertension model (weight = 0.784). RCS regression demonstrated that nitrate (nonlinearity P = 0.205) and perchlorate (nonlinearity P = 0.701) were linearly associated with decreased occurrence of hypertension. Concurrent exposure to nitrate, thiocyanate, and perchlorate is associated with a decreased risk of hypertension, with the greatest influence coming from nitrate probably; urinary specific thiocyanate alone had an insignificant association with hypertension.

Environmental occurrence, toxicity and remediation of perchlorate - A review

Perchlorate (ClO4-) comes under the class of contaminants called the emerging contaminants that will impact environment in the near future. A strong oxidizer by nature, perchlorate has received significant observation due to its occurrence, reactive nature, and persistence in varied environments such as surface water, groundwater, soil, and food. Perchlorate finds its use in number of industrial products ranging from missile fuel, fertilizers, and fireworks. Perchlorate exposure occurs when naturally occurring or manmade perchlorate in water or food is ingested. Perchlorate ingestion affects iodide absorption into the thyroid, thereby causing a decrease in the synthesis of thyroid hormone, a very crucial component needed for metabolism, neural development, and a number of other physiological functions in the body. Perchlorate remediation from ground water and drinking water is carried out through a series of physical-chemical techniques like ion (particle) transfer and reverse osmosis. However, the generation of waste through these processes are difficult to manage, so the need for alternative treatment methods occur. This review talks about the hybrid technologies that are currently researched and gaining momentum in the treatment of emerging contaminants, namely perchlorate.

Determination of exposure to major iodide ion uptake inhibitors through drinking waters

Goiter, abnormal enlargement of the thyroid gland, is a significant worldwide public health problem. Iodine deficiency is known as the most common cause. Iodine is actively transported as iodide ion (I^-) using Sodium Iodide Symporter (NIS) and sufficient blocking of I^- transportation prevents the synthesis of thyroid hormones. The transportation can be blocked by some polyatomic anions known as I^- uptake inhibitors. Perchlorate (ClO₄^-), thiocyanate (SCN^-) and nitrate (NO₃^-) are reported as the major I^- uptake inhibitors and exposure could be through various routes. Drinking water is an important exposure route. Since water is essential to sustain life, drinking water safety is very important for the protection of public health. However, as a result of natural and human-based processes, water can be contaminated and contamination of drinking water is a global food safety problem due to causing significant health and environmental problemsIn that context, this study aims to determine exposure levels to I^- uptake inhibitors that arise from drinking waters at five different districts in Antalya, Turkey. Collected water samples contained NO₃^- and ClO₄^- in the range of 0.86-47.42 mg/L and <LOQ-0.11 mg/L, respectively. SCN^- levels were <LOQ in all samples. Daily exposure was calculated for different age groups of 2-65+ years using contaminant levels, water consumption and body weight data. Mean NO₃^- and ClO₄^- exposure levels were in the range of 115.89-375.06 and 0.07-0.22 μg/kg bw/d, respectively. Exposure levels were decreased with increasing age and the highest exposure levels were calculated for children due to their lower body weight. Although no risk was determined for the I^- uptake inhibitors in tested locations based on the guideline values recommended by EPA and WHO, there has been a need for more exposure assessment studies in the areas where the high prevalence of goiter is observed all over the world.

Association of exposures to perchlorate, nitrate, and thiocyanate with allergic symptoms: A population-based nationwide cohort study

Allergic diseases have been one of the leading causes of chronic disorders in the United States. Animal studies have suggested that exposures to perchlorate, nitrate, and thiocyanate could induce allergic inflammation. However, the associations have not been examined among general populations. Here, we investigated data of 7030 participants aged ≥6 years from the National Health and Nutritional Examination Survey (NHANES) 2005-2006. Urinary levels of perchlorate, nitrate, and thiocyanate were measured by ion chromatography combined with electrospray tandem mass spectrometry. Information on allergic symptoms (hay fever, allergy, rash, sneeze, wheeze, eczema, and current asthma) was collected by questionnaire. Allergic sensitization was defined by a concentration ≥150 kU/L for total immunoglobulin E (IgE) levels. The associations were estimated using multivariate-adjusted logistic regression models. A positive association was observed for urinary nitrate and eczema (p < 0.001 for the trend). Compared with quartile 1 (lowest quartile), the odds ratios of eczema with 95% confidence intervals [ORs (95% CIs)] from quartiles 2 to 4 were 1.72 (95% CI, 1.41, 2.09), 1.94 (1.53, 2.47) and 2.10 (1.49, 2.97) for urinary nitrate. In addition, urinary thiocyanate was positively related to sneeze (OR_{Q4 vs. Q1}: 1.25, 95% CI: 1.01, 1.55; p = 0.015 for the trend). However, urinary perchlorate was not correlated with any allergic-related outcome. Additionally, the associations were different among subgroups in a four-level polytomous model. Thus, our results suggested that exposures to nitrate and thiocyanate may be associated with allergic symptoms. Further investigations are warranted to concentrate on the practical strategies to monitor exposure levels and the latent mechanisms of the relationship between exposure and allergy.

Perchlorate - properties, toxicity and human health effects: an updated review

Interest in perchlorate as environmental pollutant has increased since 1997, when high concentrations have been found in the waters of the Colorado River, USA. Perchlorate is very persistent in nature and it is slowly degraded. Although harmful effects of large doses of perchlorate on thyroid function have been proven, the environmental effects are still unclear. The primary objective of the present review is to collect prevailing data of perchlorate exposure and to discuss its impact on human health. The results show that more than 50% of reviewed works found significant associations of perchlorate exposure and human health. This review consists of the following sections: general information of perchlorate sources, its properties and determination methods, role and sources in human body including food and water intake, overview of the scientific literature on the research on the effect of perchlorate on human health from 2010 to 2020. Finally, conclusions and recommendations on future perchlorate studies concerning human exposure are presented.