Pregnant ewes exposed to multiple endocrine disrupting pollutants through sewage sludge-fertilized pasture show an anti-estrogenic effect in their trabecular bone

Developmental programming: Impact of preconceptional and gestational exposure to a real-life environmental chemical mixture on maternal steroid, cytokine and oxidative stress milieus in sheep

BACKGROUND

Gestational exposure to environmental chemicals (ECs) is associated with adverse, sex-specific offspring health effects of global concern. As the maternal steroid, cytokine and oxidative stress milieus can have critical effects on pregnancy outcomes and the programming of diseases in offspring, it is important to study the impact of real-life EC exposure, i.e., chronic low levels of mixtures of ECs on these milieus. Sheep exposed to biosolids, derived from human waste, is an impactful model representing the ECs humans are exposed to in real-life. Offspring of sheep grazed on biosolids-treated pasture are characterized by reproductive and metabolic disruptions.

OBJECTIVE

To determine if biosolids exposure disrupts the maternal steroid, cytokine and oxidative stress milieus, in a fetal sex-specific manner.

METHODS

Ewes were maintained before mating and through gestation on pastures fertilized with biosolids (BTP), or inorganic fertilizer (Control). From maternal plasma collected mid-gestation, 19 steroids, 14 cytokines, 6 oxidative stress markers were quantified. Unpaired t-test and ANOVA were used to test for differences between control and BTP groups (n = 15/group) and between groups based on fetal sex, respectively. Correlation between the different markers was assessed by Spearman correlation.

RESULTS

Concentrations of the mineralocorticoids - deoxycorticosterone, corticosterone, the glucocorticoids - deoxycortisol, cortisol, cortisone, the sex steroids - androstenedione, dehydroepiandrosterone, 16-OH-progesterone and reactive oxygen metabolites were higher in the BTP ewes compared to Controls, while the proinflammatory cytokines IL-1β and IL-17A and anti-inflammatory IL-36RA were decreased in the BTP group. BTP ewes with a female fetus had lower levels of IP-10.

DISCUSSION

These findings suggest that pre-conceptional and gestational exposure to ECs in biosolids increases steroids, reactive oxygen metabolites and disrupts cytokines in maternal circulation, likely contributors to the aberrant phenotypic outcomes seen in offspring of BTP sheep - a translationally relevant precocial model.

Developmental programming: Preconceptional and gestational exposure of sheep to a real-life environmental chemical mixture alters maternal metabolome in a fetal sex-specific manner

BACKGROUND

Everyday, humans are exposed to a mixture of environmental chemicals some of which have endocrine and/or metabolism disrupting actions which may contribute to non-communicable diseases. The adverse health impacts of real-world chemical exposure, characterized by chronic low doses of a mixture of chemicals, are only recently emerging. Biosolids derived from human waste represent the environmental chemical mixtures humans are exposed to in real life. Prior studies in sheep have shown aberrant reproductive and metabolic phenotypes in offspring after maternal biosolids exposure.

OBJECTIVE

To determine if exposure to biosolids perturbs the maternal metabolic milieu of pregnant ewes, in a fetal sex-specific manner.

METHODS

Ewes were grazed on inorganic fertilizer (Control) or biosolids-treated pastures (BTP) from before mating and throughout gestation. Plasma from pregnant ewes (Control n = 15, BTP n = 15) obtained mid-gestation were analyzed by untargeted metabolomics. Metabolites were identified using Agilent MassHunter. Multivariate analyses were done using MetaboAnalyst 5.0 and confirmed using SIMCA.

RESULTS

Univariate and multivariate analysis of 2301 annotated metabolites identified 193 differentially abundant metabolites (DM) between control and BTP sheep. The DM primarily belonged to the super-class of lipids and organic acids. 15-HeTrE, oleamide, methionine, CAR(3:0(OH)) and pyroglutamic acid were the top DM and have been implicated in the regulation of fetal growth and development. Fetal sex further exacerbated differences in metabolite profiles in the BTP group. The organic acids class of metabolites was abundant in animals with male fetuses. Prenol lipid, sphingolipid, glycerolipid, alkaloid, polyketide and benzenoid classes showed fetal sex-specific responses to biosolids.

DISCUSSION

Our study illustrates that exposure to biosolids significantly alters the maternal metabolome in a fetal sex-specific manner. The altered metabolite profile indicates perturbations to fatty acid, arginine, branched chain amino acid and one‑carbon metabolism. These factors are consistent with, and likely contribute to, the adverse phenotypic outcomes reported in the offspring.

Toward a better understanding of the effects of endocrine disrupting compounds on health: Human-relevant case studies from sheep models

There are many challenges to overcome in order to properly understand both the exposure to, and effects of, endocrine disruptors (EDs). This is particularly true with respect to fetal life where ED exposures are a major issue requiring toxicokinetic studies of materno-fetal exchange and identification of pathophysiological consequences. The sheep, a large, monotocous, species, is very suitable for in utero fetal catheterization allowing a modelling approach predictive of human fetal exposure. Predicting adverse effects of EDs on human health is frequently impeded by the wide interspecies differences in the regulation of endocrine functions and their effects on biological processes. Because of its similarity to humans as regards gestational and thyroid physiologies and brain ontogeny, the sheep constitutes a highly appropriate model to move one step further on thyroid disruptor hazard assessment. As a grazing animal, the sheep has also proven to be useful in the evaluation of the consequences of chronic environmental exposure to "real-life" complex mixtures at different stages of the reproductive life cycle.

Low-dose developmental exposure to bisphenol A induces sex-specific effects in bone of Fischer 344 rat offspring

BACKGROUND

Bisphenol A (BPA) is a component of polycarbonate plastics to which humans are regularly exposed at low levels, and an endocrine disruptor with effects on several hormonal systems. Bone is a sensitive hormone target tissue, and we have recently shown that in utero and lactational exposure to 25µg BPA/kg BW/day alters femoral geometry in rat offspring.

OBJECTIVE

To investigate bone effects in rat offspring after developmental exposure to a BPA dose in the range of human daily exposure (0.1-1.5µg/kg BW/day) as well as a dose to corroborate previous findings.

METHODS

Pregnant Fischer 344 rats were exposed to BPA via drinking water corresponding to 0.5µg/kg BW/day: [0.5], (n=21) or 50µg/kg BW/day: [50], (n = 16) from gestational day 3.5 until postnatal day 22, while controls were given only vehicle (n = 25). The offspring was sacrificed at 5 weeks of age. Bone effects were analyzed using peripheral quantitative computed tomography (pQCT), the 3-point bending test, plasma markers of bone turnover, and gene expression in cortical bone and bone marrow.

RESULTS

Compared to controls, male offspring developmentally exposed to BPA had shorter femurs. pQCT analysis revealed effects in the [0.5] group, but not in the [50] group; BPA reduced both trabecular area (-3.9%, p < 0.01) and total cross sectional area (-4.1%, p < 0.01) of femurs in the [0.5] group, whereas no effects were seen on bone density. Conversely, bone length and size were not affected in female offspring. However, the procollagen type I N-terminal propeptide (P1NP), a peptide formed during type 1 collagen synthesis, was increased in plasma (42%: p < 0.01) in female offspring exposed to [0.5] of BPA, although collagen gene expression was not increased in bone. The biomechanical properties of the bones were not altered in either sex. Bone marrow mRNA expression was only affected in male offspring.

CONCLUSIONS

Developmental low-dose exposure to BPA resulted in sex-specific bone effects in rat offspring. A dose approximately eight times lower than the current temporary EFSA human tolerable daily intake of 4µg/kg BW/day, reduced bone length and size in male rat offspring. Long-term studies are needed to clarify whether the increased plasma levels of P1NP in female offspring reflect development of fibrosis.

Association of Perfluoroalkyl Substances, Bone Mineral Density, and Osteoporosis in the U.S. Population in NHANES 2009-2010

BACKGROUND

Perfluoroalkyl substances (PFASs), including perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA), are detectable in the serum of 95% of the U.S.

OBJECTIVE

Considering the role of PFASs as endocrine disruptors, we examined their relationships with bone health.

METHODS

The association between serum PFAS concentration and bone mineral density at total femur (TFBMD), femoral neck (FNBMD), lumbar spine (LSBMD), and physician-diagnosed osteoporosis was assessed in 1,914 participants using data from the National Health and Nutritional Examination Survey 2009-2010.

RESULTS

The mean age of the participants was 43 years. Men had higher serum PFAS concentrations than women (p < 0.001) except for PFNA. In both sexes, serum PFOS concentrations were inversely associated with FNBMD (p < 0.05). In women, significant negative associations were observed for natural log (ln)-transformed PFOS exposure with TFBMD and FNBMD, and for ln-transformed PFOA exposure with TFBMD (p < 0.05). In postmenopausal women, serum PFOS was negatively associated with TFBMD and FNBMD, and PFNA was negatively associated with TFBMD, FNBMD, and LSBMD (all p < 0.05). With one log unit increase in serum PFOA, PFHxS, and PFNA, osteoporosis prevalence in women increased as follows: [adjusted odds ratios (aORs)] 1.84 (95% CI: 1.17, 2.905), 1.64 (95% CI: 1.14, 2.38), and 1.45 (95% CI: 1.02, 2.05), respectively. In women, the prevalence of osteoporosis was significantly higher in the highest versus the lowest quartiles of PFOA, PFHxS, and PFNA, with aORs of 2.59 (95% CI: 1.01, 6.67), 13.20 (95% CI: 2.72, 64.15), and 3.23 (95% CI: 1.44, 7.21), respectively, based on 77 cases in the study sample.

CONCLUSION

In a representative sample of the U.S. adult population, serum PFAS concentrations were associated with lower bone mineral density, which varied according to the specific PFAS and bone site assessed. Most associations were limited to women. Osteoporosis in women was also associated with PFAS exposure, based on a small number of cases.

CITATION

Khalil N, Chen A, Lee M, Czerwinski SA, Ebert JR, DeWitt JC, Kannan K. 2016. Association of perfluoroalkyl substances, bone mineral density, and osteoporosis in the U.S. population in NHANES 2009-2010. Environ Health Perspect 124:81-87; http://dx.doi.org/10.1289/ehp.1307909.

Impact of sludge deposition on biodiversity

Sludge deposition in the environment is carried out in several countries. It encompasses the dispersion of treated or untreated sludge in forests, marsh lands, open waters as well as estuarine systems resulting in the gradual accumulation of toxins and persistent organic compounds in the environment. Studies on the life cycle of compounds from sludge deposition and the consequences of deposition are few. Most reports focus rather on treatment-methods and approaches, legislative aspects as well as analytical evaluations of the chemical profiles of sludge. This paper reviews recent as well as some older studies on sludge deposition in forests and other ecosystems. From the literature covered it can be concluded that sludge deposition induces two detrimental effects on the environment: (1) raising of the levels of persistent toxins in soil, vegetation and wild life and (2) slow and long-termed biodiversity-reduction through the fertilizing nutrient pollution operating on the vegetation. Since recent studies show that eutrophication of the environment is a major threat to global biodiversity supplying additional nutrients through sludge-based fertilization seems imprudent. Toxins that accumulate in the vegetation are transferred to feeding herbivores and their predators, resulting in a reduced long-term survival chance of exposed species. We briefly review current legislation for sludge deposition and suggest alternative routes to handling this difficult class of waste.

A study on temporal trends and estimates of fate of Bisphenol A in agricultural soils after sewage sludge amendment

Temporal concentration trends of BPA in soils were investigated following sewage sludge application to pasture (study 1: short term sludge application; study 2: long term multiple applications over 13 years). The background levels of BPA in control soils were similar, ranging between 0.67-10.57 ng g(-1) (mean: 3.02 ng g(-1)) and 0.51-6.58 ng g(-1) (mean: 3.22 ng g(-1)) for studies 1 and 2, respectively. Concentrations in both treated and control plots increased over the earlier sampling times of the study to a maximum and then decreased over later sampling times, suggesting other sources of BPA to both the treated and control soils over the study period. In study 1 there was a significant treatment effect of sludge application in the autumn (p=0.002) although no significant difference was observed between treatment and control soils in the spring. In study 2 treated soils contained considerably higher BPA concentrations than controls ranging between 12.89-167.9 ng g(-1) (mean: 63.15 ng g(-1)). This and earlier studies indicate the long-term accumulation of multiple contaminants by multiple sewage sludge applications over a prolonged period although the effects of the presence of such contaminant mixtures have not yet been elucidated. Fugacity modelling was undertaken to estimate partitioning of Bisphenol A (soil plus sewage: pore water: soil air partitioning) and potential uptake into a range of food crops. While Bisphenol A sorbs strongly to the sewage-amended soil, 4% by mass was predicted to enter soil pore water resulting in significant uptake by crops particularly leafy vegetables (3.12-75.5 ng g(-1)), but also for root crops (1.28-31.0 ng g(-1)) with much lower uptake into cereal grains (0.62-15.0 ng g(-1)). This work forms part of a larger programme of research aimed at assessing the risks associated with the long-term application of sewage sludge to agricultural soils.

Performance of calcium peroxide for removal of endocrine-disrupting compounds in waste activated sludge and promotion of sludge solubilization

Removal of six phenolic endocrine disrupting compounds (EDCs) (estrone, 17β-estradiol, 17α-ethinylestradiol, estriol, bisphenol A, and 4-nonylphenols) from waste activated sludge (WAS) was investigated using calcium peroxide (CaO2) oxidation. Effects of initial pH and CaO2 dosage were investigated. The impacts of CaO2 treatment on sludge solubilization and anaerobic digestion were also evaluated. Specifically, the role of reactive oxygen species (ROS) in EDC degradation during CaO2 oxidation was tested. Effects of 6 metal ions contained in the sludge matrix on EDC degradation were also evaluated. The results showed that CaO2 treatment can be a promising technology for EDC removal and facilitating sludge reuse. The EDC removal efficiencies increased with the increase in CaO2 dosage. At CaO2 doses of more than 0.34 g per gram of total solid (g g(-1) TS), more than 50% of EDCs were removed in a wide pH range of 2-12. Higher removal efficiencies were achieved at initial pH values of 12 and 2. The products of EDCs during CaO2 oxidation had less estrogenic activity than the originals. Under the conditions of neutral pH and CaO2 dosage = 0.34 g g(-1) TS, the sludge solubilization can be improved by increasing the soluble total organic carbon (STOC) and volatile suspended solids (VSS) reduction by 25% and 27% in 7 d, respectively; the volatile fatty acid (VFA) production was enhanced by 96% in the 15 d following anaerobic digestion. The ROS released by CaO2 are the main factors contributing to EDC removal, among which, hydroxyl radicals (OH) play the most important role. Metal ions contained in the sludge matrix also affected EDC removal. For most cases, Fe, Cu, and Zn had positive effects; Mn and Ag had negative effects; and Mg had an insignificant effect on EDC removal.

Removal of phenolic endocrine disrupting compounds from waste activated sludge using UV, H2O2, and UV/H2O2 oxidation processes: effects of reaction conditions and sludge matrix

Removal of six phenolic endocrine disrupting compounds (EDCs) (estrone, 17β-estradiol, 17α-ethinylestradiol, estriol, bisphenol A, and 4-nonylphenols) from waste activated sludge (WAS) was investigated using ultraviolet light (UV), hydrogen peroxide (H2O2), and the combined UV/H2O2 processes. Effects of initial EDC concentration, H2O2 dosage, and pH value were investigated. Particularly, the effects of 11 metal ions and humic acid (HA) contained in a sludge matrix on EDC degradation were evaluated. A pseudo-first-order kinetic model was used to describe the EDC degradation during UV, H2O2, and UV/H2O2 treatments of WAS. The results showed that the degradation of the 6 EDCs during all the three oxidation processes fitted well with pseudo-first-order kinetics. Compared with the sole UV irradiation or H2O2 oxidation process, UV/H2O2 treatment was much more effective for both EDC degradation and WAS solubilization. Under their optimal conditions, the EDC degradation rate constants during UV/H2O2 oxidation were 45-197 times greater than those during UV irradiation and 11-53 times greater than those during H2O2 oxidation. High dosage of H2O2 and low pH were favorable for the degradation of EDCs. Under the conditions of pH = 3, UV wavelength = 253.7 nm, UV fluence rate = 0.069 mW cm(-2), and H2O2 dosage = 0.5 mol L(-1), the removal efficiencies of E1, E2, EE2, E3, BPA, and NP in 2 min were 97%, 92%, 95%, 94%, 89%, and 67%, respectively. The hydroxyl radical (OH) was proved to take the most important role for the removal of EDCs. Metal ions in sludge could facilitate the removal of EDCs during UV/H2O2 oxidation. Fe, Ag, and Cu ions had more obvious effects compared with other metal ions. The overall role of HA was dependent on the balance between its competition as organics and its catalysis/photosensitization effects. These indicate that the sludge matrix plays an important role in the degradation of EDCs.

Reproduction Symposium: does grazing on biosolids-treated pasture pose a pathophysiological risk associated with increased exposure to endocrine disrupting compounds?

Biosolids (processed human sewage sludge), which contain low individual concentrations of an array of contaminants including heavy metals and organic pollutants such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), and polychlorinated dibenzodioxins/polychlorinated dibenzofurans known to cause physiological disturbances, are increasingly being used as an agricultural fertilizer. This could pose a health threat to both humans and domestic and wild animal species. This review summarizes results of a unique model, used to determine the effects of exposure to mixtures of environmentally relevant concentrations of pollutants, in sheep grazed on biosolids-treated pastures. Pasture treatment results in nonsignificant increases in environmental chemical (EC) concentrations in soil. Whereas EC concentrations were increased in some tissues of both ewes and their fetuses, concentrations were low and variable and deemed to pose little risk to consumer health. Investigation of the effects of gestational EC exposure on fetal development has highlighted a number of issues. The results indicate that gestational EC exposure can adversely affect gonadal development (males and females) and that these effects can impact testicular morphology, ovarian follicle numbers and health, and the transcriptome and proteome in adult animals. In addition, EC exposure can be associated with altered expression of GnRH, GnRH receptors, galanin receptors, and kisspeptin mRNA within the hypothalamus and pituitary gland, gonadotroph populations within the pituitary gland, and regional aberrations in thyroid morphology. In most cases, these anatomical and functional differences do not result in altered peripheral hormone concentrations or reproductive function (e.g., lambing rate), indicating physiological compensation under the conditions tested. Physiological compensation is also suggested from studies that indicate that EC effects may be greater when exposure occurs either before or during gestation compared with EC exposure throughout life. With regard to human and animal health, this body of work questions the concept of safe individual concentration of EC when EC exposure typically occurs as complex mixtures. It suggests that developmental EC exposure may affect many different physiological systems, with some sex-specific differences in EC sensitivity, and that EC effects may be masked under favorable physiological conditions.

Is the bone tissue of ring-billed gulls breeding in a pollution hotspot in the St. Lawrence River, Canada, impacted by halogenated flame retardant exposure?

Bone metabolism is a tightly regulated process that controls bone remodeling and repair in addition to maintaining circulating calcium and phosphate levels. It has been shown that certain organohalogen contaminants may adversely impact bone tissue metabolism and structure in wildlife species. However, exceedingly few studies have addressed the bone-related effects of organohalogen exposure in birds. The objective of the present study was to investigate the associations between markers of bone metabolism and structural integrity, and concentrations of established and current-use halogenated flame retardants (FRs) in ring-billed gulls (Larus delawarensis) nesting in a known FR hotspot area in the St. Lawrence River (Montreal, Canada). Bone metabolism was assessed using plasma calcium and inorganic phosphate levels, and alkaline phophatase activity, while bone (tarsus; trabecular and cortical sections) structure quality was examined using the percentage of bone tissue comprised in the total bone volume (Bv/Tv) and bone mineral density (BMD). Bv/Tv and BMD of the tarsus tended (not significant) to be positively associated with circulating calcium levels in male ring-billed gulls. Moreover, concentrations of FRs in male bird liver (brominated diphenyl ether (BDE)-154, -183, -201, and -209) and plasma (BDE-209) were negatively correlated with trabecular and cortical BMD of the tarsus. These correlative associations may suggest light demineralization of bone tissue associated with FR exposure in male ring-billed gulls. Present findings provide some evidence that bone (tarsus) metabolism and mineral composition may be impacted in high FR-exposed (mainly to PBDEs) ring-billed gulls breeding in the highly urbanized Montreal region.

Peri-conceptional changes in maternal exposure to sewage sludge chemicals disturbs fetal thyroid gland development in sheep

Ewes were exposed to sewage sludge-fertilized pastures in a study designed investigate pre-conceptual and/or gestational exposure to environmental chemicals. The in utero impact on fetal thyroid morphology and function at day 110 (of 145) of pregnancy was then determined. Pre-conceptual exposure increased the relative thyroid organ weights in male fetuses. The number of thyroid follicles in thyroids of fetuses after pre-conceptual or gestational exposure was reduced. This correlated with an increase in Ki67 positive cells. Pre-conceptual exposure to sewage sludge reduced small blood vessels in fetal thyroids. Thyroid tissues of exposed fetuses contained regions where mature angio-follicular units were reduced exhibiting decreased immunostaining for sodium-iodide symporter (NIS). Fetal plasma levels of fT3 and fT4 in exposed animals, however, were not different from controls suggesting compensatory changes in the thyroid gland to maintain homeostasis in exposed fetuses. The regional aberrations in thyroid morphology may impact on the post-natal life of the exposed offspring.

Overcoming the toxicity effects of municipal wastewater sludge and biosolid extracts in the Yeast Estrogen Screen (YES) assay

For nearly two decades, the Yeast Estrogen Screen (YES) has been used as a valuable tool for determining the total estrogenic potency of various environmental samples, including influent and effluent streams at municipal wastewater plants. However, applying the YES assay to wastewater sludges and stabilized biosolids has been problematic. This is due to co-extracted compounds from the solids either proving toxic to the yeast or masking the presence of estrogenic substances. The present research describes the development and validation of sample preparation steps that mitigate the toxicity effects of municipal wastewater sludge and biosolid samples in the YES assay, while allowing for reliable dose-dependent expression of estrogenic activity. A copper work-up for sulfur removal and chromatographic cleanup with silica and alumina were required in addition to solid-phase extraction to adequately remove interfering compounds. Sample stabilization methods such as autoclaving, lyophilization and formaldehyde treatment were found to be detrimental to the assay. Hence, heat-drying is recommended to prevent cytotoxicity and the degradation of estrogenic substances.

Anthropogenic pollutants – an insidious threat to animal health and productivity?

Summary

Geographic variation in tissue accumulation of endocrine disrupting compounds (EDCs) in grazing sheep

Muscle tissue was collected from ewes and lambs derived from farms throughout Scotland and sample concentrations of five endocrine disrupting compound groups were determined. Farms of origin were categorised according to geographic region. There were few statistically-significant differences with region or distance from cities. However, the magnitude of the difference between the highest and lowest mean values in ewe muscle from different regions exceeded 30% for 13 of the 15 compounds that were consistently detected in muscle, with animals derived from the industrialised region having the highest mean values for 11 of the 13 compounds. A less marked trend was apparent in the lamb muscle (8 of 13 highest were in the industrialised region). The physiological effects of such small differences in exposure to mixtures of pollutants remain to be determined.