Testicular microlithiasis and neoplastic lesions in wild eland (Tragelaphus oryx): possible effects of exposure to environmental pollutants?

Does environmental pollution affect male reproductive system in naturally exposed vertebrates? A systematic review

Due to environmental contamination, the environment constantly receives pollutants from various anthropic actions. These pollutants put ecological health at risk due to contamination and accumulation in living organisms, including wild animals and humans. Exposure can cause physiological, morphological, and behavioral changes in living beings. In this context, laboratory studies have frequently investigated how environmental contaminants affect the male reproductive system and gametes. However, few studies have examined how these contaminants affect male reproduction in naturally exposed animals. To better understand this topic, we conducted a systematic review of the effects of exposing male vertebrate animals to polluted environments on their reproductive functions. After an extensive search using the PubMed/MEDLINE, Scopus, and Web of Science databases, 39 studies met our inclusion criteria and were eligible for this review. This study showed that reproductive damages were frequent in fishes, amphibians, reptiles, birds, and mammals exposed to contaminated environments. Wild animals are exposed mainly to endocrine-disrupting compounds (EDCs), toxic metals, and radiation. Exposure to pollutants causes a reduction in androgen levels, impaired spermatogenesis, morphological damage to reproductive organs, and decreased sperm quality, leading to reduced fertility and population decline. Although several species have been studied, the number of studies is limited for some groups of vertebrates. Wildlife has proven valuable to our understanding of the potential effects of environmental contaminants on human and ecosystem health. Thus, some recommendations for future investigations are provided. This review also creates a baseline for the understanding state of the art in reproductive toxicology studies.

Agrochemicals in freshwater systems and their potential as endocrine disrupting chemicals: A South African context

South Africa is the largest agrochemical user in sub-Saharan Africa, with over 3000 registered pesticide products. Although they reduce crop losses, these chemicals reach non-target aquatic environments via leaching, spray drift or run-off. In this review, attention is paid to legacy and current-use pesticides reported in literature for the freshwater environment of South Africa and to the extent these are linked to endocrine disruption. Although banned, residues of many legacy organochlorine pesticides (endosulfan and dichlorodiphenyltrichloroethane (DDT)) are still detected in South African watercourses and wildlife. Several current-use pesticides (triazine herbicides, glyphosate-based herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D) and chlorpyrifos) have also been reported. Agrochemicals can interfere with normal hormone function of non-target organism leading to various endocrine disrupting (ED) effects: intersex, reduced spermatogenesis, asymmetric urogenital papillae, testicular lesions and infertile eggs. Although studies investigating the occurrence of agrochemicals and/or ED effects in freshwater aquatic environments in South Africa have increased, few studies determined both the levels of agricultural pesticides present and associated ED effects. The majority of studies conducted are either laboratory-based employing in vitro or in vivo bioassays to determine ED effects of agrochemicals or studies that investigate environmental concentrations of pesticides. However, a combined approach of bioassays and chemical screening will provide a more comprehensive overview of agrochemical pollution of water systems in South Africa and the risks associated with long-term chronic exposure.

Environmental exposure to nonylphenol and cancer progression Risk-A systematic review

Environmental exposure to nonylphenol (NP) can adversely affect human and wildlife health. A systematic review was conducted to evaluate the relationship between environmental NP exposure and cancer progression risk. Literature surveys were conducted within several international databases using appropriate keywords. A comprehensive search yielded 58 eligible studies involving a wide range of adverse effects, exposure assessment methods, study designs, and experimental models. Most studies reported that NP strongly induced breast cancer progression in intended experiments. Positive associations between NP exposure and ovarian, uterine, pituitary, and testicular cancers were also reported. Although some studies reported no relation between environmental NP exposure and tumour and/or cancer progression, NP (a known endocrine disrupting chemical) induced action mechanisms in multiple experimental models and may interfere with/hyper-activate oestrogen signalling. Secretion of oestrogen and development of reproductive tissues like breasts, uteruses, and ovaries showed strong associations with possible neoplasia (i.e., uncontrolled development of tumours and/or malignant cancers). Findings of this study are important for informing policymakers to pass legislation limiting the use of environmental contaminants such as NP before all adverse effects of exposure have been determined.

Untangling the association between environmental endocrine disruptive chemicals and the etiology of male genitourinary cancers

Endocrine disrupting chemicals disrupt normal physiological function of endogenous hormones, their receptors, and signaling pathways of the endocrine system. Most endocrine disrupting chemicals exhibit estrogen/androgen agonistic and antagonistic activities that impinge upon hormone receptors and related pathways. Humans are exposed to endocrine disrupting chemicals through food, water and air, affecting the synthesis, release, transport, metabolism, binding, function and elimination of naturally occurring hormones. The urogenital organs function as sources of steroid hormones, are targeted end organs, and participate within systemic feedback loops within the endocrine system. The effects of endocrine disruptors can ultimately alter cellular homeostasis leading to a broad range of health effects, including malignancy. Human cancer is characterized by uncontrolled cell proliferation, mechanisms opposing cell-death, development of immortality, induction of angiogenesis, and promotion of invasion/metastasis. While hormonal malignancies of the male genitourinary organs are the second most common types of cancer, the molecular effects of endocrine disrupting chemicals in hormone-driven cancers has yet to be fully explored. In this commentary, we examine the molecular evidence for the involvement of endocrine disrupting chemicals in the genesis and progression of hormone-driven cancers in the prostate, testes, and bladder. We also report on challenges that have to be overcome to drive our understanding of these chemicals and explore the potential avenues of discovery that could ultimately allow the development of tools to prevent cancer in populations where exposure is inevitable.

Endocrine Disruptors and Health Effects in Africa: A Call for Action

BACKGROUND

Africa faces a number of unique environmental challenges. Unfortunately, it lacks the infrastructure needed to support the comprehensive environmental studies that could provide the scientific basis to inform environmental policies. There are a number of known sources of endocrine-disrupting chemicals (EDCs) and other hazardous chemicals in Africa. However, a coordinated approach to identify and monitor these contaminants and to develop strategies for public health interventions has not yet been made.

OBJECTIVES

This commentary summarizes the scientific evidence presented by experts at the First African Endocrine Disruptors meeting. We describe a "call to action" to utilize the available scientific knowledge to address the impact of EDCs on human and wildlife health in Africa.

DISCUSSION

We identify existing knowledge gaps about exposures to EDCs in Africa and describe how well-designed research strategies are needed to address these gaps. A lack of resources for research and a lag in policy implementation slows down intervention strategies and poses a challenge to advancing future health in Africa.

CONCLUSION

To address the many challenges posed by EDCs, we argue that Africans should take the lead in prioritization and evaluation of environmental hazards, including EDCs. We recommend the institution of education and training programs for chemical users, adoption of the precautionary principle, establishment of biomonitoring programs, and funding of community-based epidemiology and wildlife research programs led and funded by African institutes and private companies. https://doi.org/10.1289/EHP1774.

What should it take to describe a substance or product as 'sperm-safe'

BACKGROUND

Male reproductive potential continues to be adversely affected by many environmental, industrial and pharmaceutical toxins. Pre-emptive testing for reproductive toxicological (side-)effects remains limited, or even non-existent. Many products that come into direct contact with spermatozoa lack adequate testing for the absence of adverse effects, and numerous products that are intended for exposure to spermatozoa have only a general assumption of safety based on the absence of evidence of actual harm. Such assumptions can have unfortunate adverse impacts on at-risk individuals (e.g. couples who are trying to conceive), illustrating a clear need for appropriate up-front testing to establish actual 'sperm safety'.

METHODS

After compiling a list of general areas within the review's scope, relevant literature and other information was obtained from the authors' personal professional libraries and archives, and supplemented as necessary using PubMed and Google searches. Review by co-authors identified and eliminated errors of omission or bias.

RESULTS

This review provides an overview of the broad range of substances, materials and products that can affect male fertility, especially through sperm fertilizing ability, along with a discussion of practical methods and bioassays for their evaluation. It is concluded that products can only be claimed to be 'sperm-safe' after performing objective, properly designed experimental studies; extrapolation from supposed predicate products or other assumptions cannot be trusted.

CONCLUSIONS

We call for adopting the precautionary principle, especially when exposure to a product might affect not only a couple's fertility potential but also the health of resulting offspring and perhaps future generations.