Polychlorinated biphenyls and dibenzofurans increased abnormal sperm morphology without alterations in aneuploidy: The Yucheng study

Establishing the Mechanisms Involved in the Environmental Exposure to Polychlorinated Biphenyls (PCBs) in the Risk of Male Infertility

Exposure to toxic chemicals, such as plasticizers, alkylphenol compounds, and polychlorinated biphenyls (PCBs), has increased due to environmental contamination. PCBs, categorized as persistent organic pollutants (POPs), are lipophilic chemicals commonly used in lubricants, cutting oils, and electrical insulators. PCBs may have detrimental effects on hormone-producing glands, potentially contributing to male infertility. Thus, the objective of this study was to provide a comprehensive overview of the adverse effects of PCBs on the male reproductive system. Searches of three electronic databases were performed using MESH terms and 32 studies were included. Although the exact mechanism of action for PCBs remains unclear, several PCBs are regarded as potential endocrine disruptors due to their ability to interact with hormone signaling pathways. PCBs have been found to disrupt physiological functions by mimicking endogenous hormones as agonists or antagonists, altering patterns of hormone synthesis, hormone receptor affinities or numbers, and modulating enzymes involved in hormone secretion. These reports highlight the pleiotropic nature of PCB function and the susceptibility of the reproductive system. Endocrine-disrupting PCBs can mimic, alter, or block hormonal responses, inhibiting natural signaling to the testes and epididymis via various mechanisms such as binding to sex hormone-binding globulin and androgen-binding protein or blocking cell surface receptors. Furthermore, PCBs can alter the hormonal environment in the prostate or seminal vesicles by changing the affinity of androgens for their receptors. The testicles and genital organs may be susceptible to various estrogenic effects, leading to changes in the quality or quantity of their secretions and the volume of semen.

The associations between renal disease severity and exposure to organophosphate flame retardants in patients with chronic kidney disease

Organophosphate flame retardants (OPFRs) are emerging and widespread environmental pollutants with potential health hazards, including nephrotoxicity. However, the exposure patterns and nephrotoxic potential of OPFRs are yet to be investigated in patients with chronic kidney disease (CKD). We conducted a cross-sectional study involving 166 patients with CKD stratified by estimated glomerular filtration rate (eGFR) and severity of proteinuria. The urinary concentrations of 10 OPFR compounds were measured to evaluate the exposure patterns. Clinical and urinary OPFR profiles were compared among subgroups to identify whether the OPFR compounds were independently correlated with eGFR and proteinuria. Additionally, lifestyle factors were compared among subgroups stratified by median concentrations of urinary OPFR compounds associated with renal disease severity. This study revealed universal exposure to OPFRs in the CKD population, with an overall urinary detection rate of 98.80 %. Furthermore, after adjusting for covariates, the urinary concentration of bis(2-chloroethyl) phosphate (BCEP) was identified as an independent predictor of lower eGFR (low vs high eGFR, odds ratio (OR) (95 % confidence interval (CI)), 1.761 (1.032-3.005) per log μg/g creatinine, p = 0.038), and the urinary concentration of bis(2-butoxyethyl) phosphate (BBOEP) was independently correlated with overt proteinuria in CKD patients (with vs without overt proteinuria, OR (95 % CI), 1.813 (1.065-3.086) per log μg/g creatinine, p = 0.028). Moreover, frequent seafood consumption was negatively correlated with urinary BCEP concentration (high vs low BCEP, OR (95 % CI), 0.455 (0.228-0.908), p = 0.025), and age was inversely associated with urinary BBOEP concentration (high vs low BBOEP, OR (95 % CI), 0.968 (0.937-0.999) per year, p = 0.048). In conclusion, our investigation highlights the extensive exposure to OPFRs and the independent association between renal disease severity and urinary BCEP/BBOEP concentrations in the CKD population, indicating the nephrotoxic potential of these pollutants.

Aryl Hydrocarbon Receptor and Dioxin-Related Health Hazards-Lessons from Yusho

Poisoning by high concentrations of dioxin and its related compounds manifests variable toxic symptoms such as general malaise, chloracne, hyperpigmentation, sputum and cough, paresthesia or numbness of the extremities, hypertriglyceridemia, perinatal abnormalities, and elevated risks of cancer-related mortality. Such health hazards are observed in patients with Yusho (oil disease in Japanese) who had consumed rice bran oil highly contaminated with 2,3,4,7,8-pentachlorodibenzofuran, polychlorinated biphenyls, and polychlorinated quaterphenyls in 1968. The blood concentrations of these congeners in patients with Yusho remain extremely elevated 50 years after onset. Dioxins exert their toxicity via aryl hydrocarbon receptor (AHR) through the generation of reactive oxygen species (ROS). In this review article, we discuss the pathogenic implication of AHR in dioxin-induced health hazards. We also mention the potential therapeutic use of herbal drugs targeting AHR and ROS in patients with Yusho.

Endocrine Disrupting Chemicals and Reproductive Health in Boys and Men

Male reproductive health has declined as indicated by increasing rates of cryptorchidism, i.e., undescended testis, poor semen quality, low serum testosterone level, and testicular cancer. Exposure to endocrine disrupting chemicals (EDCs) has been proposed to have a role in this finding. In utero exposure to antiandrogenic EDCs, particularly at a sensitive period of fetal testicular development, the so-called 'masculinization programming window (MPW)', can disturb testicular development and function. Low androgen effect during the MPW can cause both short- and long-term reproductive disorders. A concurrent exposure to EDCs may also affect testicular function or damage testicular cells. Evidence from animal studies supports the role of endocrine disrupting chemicals in development of male reproductive disorders. However, evidence from epidemiological studies is relatively mixed. In this article, we review the current literature that evaluated relationship between prenatal EDC exposures and anogenital distance, cryptorchidism, and congenital penile abnormality called hypospadias. We review also studies on the association between early life and postnatal EDC exposure and semen quality, hypothalamic-pituitary-gonadal axis hormone levels and testicular cancer.

Regional difference in semen quality of young men: a review on the implication of environmental and lifestyle factors during fetal life and adulthood

The prevalence of low semen quality and the incidence of testicular cancer have been steadily increasing over the past decades in different parts of the World. Although these conditions may have a genetic or epigenetic origin, there is growing evidence that multiple environmental and lifestyle factors can act alone or in combination to induce adverse effects. Exposure to these factors may occur as early as during fetal life, via the mother, and directly throughout adulthood after full spermatogenic capacity is reached. This review aims at providing an overview of past and current trends in semen quality and its relevance to fertility as well as a barometer of men’s general health. The focus will be on recent epidemiological studies of young men from the general population highlighting geographic variations in Europe. The impact of some lifestyle and environmental factors will be discussed with their role in both fetal life and adulthood. These factors include smoking, alcohol consumption, psychological stress, exposure to electromagnetic radiation, and Endocrine Disrupting Chemicals (EDCs). Finally, the challenges in investigating the influence of environmental factors on semen quality in a fast changing world are presented.

Potential Increased Risk of Trisomy 18 Observed After a Fertilizer Warehouse Fire in Brazos County and TX

Background: In this paper, we aimed to investigate the potential impacts of a fire accident in a fertilizer warehouse on chromosomal anomalies, including Trisomy 21 (T21) and Trisomy (T18) among pregnancies in Brazos County, Texas. We conducted an observational study in Brazos County, TX, with all patients of T18 and T21 cases in the live births in Brazos County between 2005–2014. The prevalence of T18 and T21 before, during, and after the accident in Brazos County were calculated and compared. The Standardized Morbidity Ratio (SMR) was applied to compare the prevalence of T18 and T21 in Brazos County to the statewide prevalence in Texas after adjusting for maternal race and age. Compared with statewide risk, the risk of T18 during the impacted years in Brazos county was found to be significantly higher (SMR = 5.0, 95% Confidence Interval(CI): 2.19–9.89), while there was no significant difference before (SMR = 0.77, 0.13–2.54) and after the accident (SMR = 0.71, 0.12–2.36). However, the prevalence of T21 during the impacted years was not significantly different from those before or after the accident. This study conclusively suggests that this fertilizer fire may be related to the increased prevalence of T18 in Brazos County, though the findings warrant further investigation.

Applying a social-ecological framework to Yucheng: 40 years after exposure to polychlorinated biphenyls and dibenzofurans

Although many epidemiological studies have been conducted on Yucheng cohorts, this incident has rarely been examined from social-ecological perspectives. This study adopted a social-ecological model as a framework to provide a more complete description of Yucheng in order to understand its effects on affected individuals, communities, and society. At first, recent studies on Yucheng victim's health effects  was updated. Long-term follow-up studies of Yucheng cohort have revealed the adverse health effects exerted on victims and their children. Subsequently, this study uses the disaster ecology model as a conceptual framework to review Yucheng. The movements of Yucheng victims and their supporters have constituted a primary actor for promoting the personal and legal rights of Yucheng victims. Finally, this study discusses how to improve future studies to effectively assist victims in their recovery from this incident.

Risk for animal and human health related to the presence of dioxins and dioxin-like PCBs in feed and food

The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of dioxins (PCDD/Fs) and DL-PCBs in feed and food. The data from experimental animal and epidemiological studies were reviewed and it was decided to base the human risk assessment on effects observed in humans and to use animal data as supportive evidence. The critical effect was on semen quality, following pre- and postnatal exposure. The critical study showed a NOAEL of 7.0 pg WHO2005-TEQ/g fat in blood sampled at age 9 years based on PCDD/F-TEQs. No association was observed when including DL-PCB-TEQs. Using toxicokinetic modelling and taking into account the exposure from breastfeeding and a twofold higher intake during childhood, it was estimated that daily exposure in adolescents and adults should be below 0.25 pg TEQ/kg bw/day. The CONTAM Panel established a TWI of 2 pg TEQ/kg bw/week. With occurrence and consumption data from European countries, the mean and P95 intake of total TEQ by Adolescents, Adults, Elderly and Very Elderly varied between, respectively, 2.1 to 10.5, and 5.3 to 30.4 pg TEQ/kg bw/week, implying a considerable exceedance of the TWI. Toddlers and Other Children showed a higher exposure than older age groups, but this was accounted for when deriving the TWI. Exposure to PCDD/F-TEQ only was on average 2.4- and 2.7-fold lower for mean and P95 exposure than for total TEQ. PCDD/Fs and DL-PCBs are transferred to milk and eggs, and accumulate in fatty tissues and liver. Transfer rates and bioconcentration factors were identified for various species. The CONTAM Panel was not able to identify reference values in most farm and companion animals with the exception of NOAELs for mink, chicken and some fish species. The estimated exposure from feed for these species does not imply a risk.

Environmental Toxins and Male Fertility

PURPOSE OF REVIEW

Global industrialization has increased population exposure to environmental toxins. A global decline in sperm quality over the last few decades raises questions about the adverse impact of environmental toxins on male reproductive health.

RECENT FINDINGS

Multiple animal- and human-based studies on exposure to environmental toxins suggest a negative impact on semen quality, in terms of sperm concentration, motility, and/or morphology. These toxins may exert estrogenic and/or anti-androgenic effects, which in turn alter the hypothalamic-pituitary-gonadal axis (HPGA), induce sperm DNA damage, or cause sperm epigenetic changes. This chapter will discuss the most recent literature about the most common environmental toxins and their impact on spermatogenesis and its consequences on male fertility. Understanding the presence and underlying mechanism of these toxins will help us preserve the integrity of the male reproduction system and formulate better regulations against their indiscriminate use.