The sustaining effects of e-waste-related metal exposure on hypothalamus-pituitary-adrenal axis reactivity and oxidative stress

Concentrations and influencing factors of 17 elements in placenta, cord blood, and maternal blood of women from an e-waste recycling area

BACKGROUND

The effects of prenatal element exposure on mothers and fetuses have generated concern. Profiles of trace and toxic elements in biological material are urgently desired, especially for women who reside near e-waste recycling facilities. The aim of this study was to investigate elements concentrations in placenta, cord blood, and maternal blood of women and to evaluate the influencing factors.

METHODS

A group of 48 women from an e-waste recycling site and a group of 31 women from a non-e-waste recycling site were recruited. Basic characteristics were collected by questionnaire and the concentrations of 17 elements in placenta, cord blood, and maternal blood samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Finally, the generalized linear model regression analysis (GLM) was used to test the association between element concentrations and possible factors.

RESULTS

Compared to the control group, the exposed group had significantly elevated cadmium (Cd), zinc (Zn), nickel (Ni), and antimony (Sb) in placenta, and higher lead (Pb) in maternal blood and cord blood (P<0.05). Sb concentration in maternal blood was significantly lower than in the control group (P<0.05). GLM analysis showed that element concentrations were mainly associated with maternal age [chromium (Cr), iron (Fe), selenium (Se), cobalt (Co), mercury (Hg) in placenta, copper (Cu) in maternal blood], education (Se, Sb in placenta), family income (Cu in maternal blood and Ni in placenta), passive smoking [Cu and Zn in placenta, Pb in maternal blood], and e-waste contact history (Hg in cord blood, Cu, Zn, and Cd in maternal blood).

CONCLUSIONS

Women in the e-waste recycling area had higher toxic element levels in the placenta and blood samples. More preventive measures were needed to reduce the risk of element exposure for mothers and fetuses in these areas.

Systematic literature review of heavy metal contamination of the Nigerian environment from e-waste management: Associated health and carcinogenic risk assessment

E-waste -the aftermath of large amount of electrical and electronic equipment ferried into Africa from which Nigeria receives a significant chunk, is composed of components known to be hazardous to health. Composition of series of heavy metals (HMs) in e-waste is traceable to many health conditions including cancer which is hitherto incompletely understood. This study harmonizes primary data on HMs from e-waste in different Nigerian environmental media including the air, soil, surface dust, water and plant. We estimated the possible health implications, single and aggregative soil and water pollution indices both in adult and children categories, carcinogenic and non-carcinogenic risks secondary to HM exposure and mapped out the possible mechanism of carcinogenesis. Analysis showed that soil, water, surface dust and plant matrices in Nigerian environment are variedly but considerably contaminated with combination of HMs. The significantly high values of the hazard quotient and hazard index of both water and surface dust matrices are indicative of adverse health effect of the non-carcinogenic risk. The highest HQ is generated by Pb and Cr through dermal exposure to soil and surface dust with mean values of 1718.48, 1146.14, 1362.10 and 1794.61 respectively among Nigerian children followed by the oral exposure. This pattern of observation is similar to that obtained for adult category. HI due to Pb and Cr in soil constitutes the highest HI (2.05E+03 and 1.18E+03 respectively) followed by surface dust. However, this study precipitates the observation that children are more at health risk than adults in contaminated environment. Carcinogenic risk also follows the same pattern of expression in the Nigerian environment. We conclude that exposure to e-waste poses significant carcinogenic and non-carcinogenic health risks and the induction of toxicity may be mediated via DNA damage, oxidative stress and inflammatory/immune cells dysfunction in Nigerian environment.

The effects of micro- and nanoplastics on the central nervous system: A new threat to humanity?

Given the widespread production and use of plastics, poor biodegradability, and inadequate recycling, micro/nanoplastics (MNPs) have caused widespread environmental pollution. As a result, humans inevitably ingest MNPs through various pathways. However, there is still no consensus on whether exposure to MNPs has adverse effects on humans. This article aims to provide a comprehensive overview of the knowledge of MNPs and the potential mechanisms of their impact on the central nervous system. Numerous in vivo and in vitro studies have shown that exposure to MNPs may pass through the blood-brain barrier (BBB) and lead to neurotoxicity through impairments in oxidative and inflammatory balance, neurotransmitter alternation, nerve conduction-related key enzymes, and impact through the gut-brain axis. It is worth noting that MNPs may act as carriers and have more severe effects on the body when co-exposed with other substances. MNPs of smaller sizes cause more severe harm. Despite the scarcity of reports directly relevant to humans, this review brings together a growing body of evidence showing that exposure to MNPs disturbs neurons and has even been found to alter the memory and behavior of organisms. This effect may lead to further potential negative influence on the central nervous system and contribute to the development of other diseases such as central nervous system inflammation and Parkinson 's-like neurodegenerative disorders. There is a need further to investigate the threat of MNPs to human health.

Exploration of Whole Blood Chromium as Biomarker of Hexavalent Chromium Exposure: Based on Literature Review and Monte Carlo Simulation

Hexavalent chromium (Cr(VI)) is a sort of common industrial poison and environmental pollutant posing great health threat to the population. Appropriate biomarkers are indispensable indicative tools in the biological monitoring and health risk assessment of Cr(VI). In this study, we explored the rationality and feasibility of whole blood Cr serving as the biomarker of internal exposure with corroboration drawn from literature review and Monte Carlo simulation. It was indicated that the whole blood Cr had practical operability in the large-scale population researches and robust biological significance with broad association with various Cr(VI)-related effect indices. The simulated distribution of whole blood Cr concentration in exposed populations was about three times higher than that of the control (13.52 ± 24.99 vs. 4.25 ± 11.37 μg/L, P < 0.05; 6.73 ± 10.92 μg/L vs. 1.96 ± 2.05 μg/L in China, P < 0.05), which suggested a great discriminatory ability that might be supported as evidence for its reasonable application.

Assessing oxidative stress resulting from environmental exposure to metals (Oids) in a middle Eastern population

Concentrations of metals and metalloids derived mainly from anthropogenic activities have increased considerably in the environment. Metals might be associated with increase reactive oxygen species (ROS) damage, potentially related to several health outcomes. This study has recruited 200 adult participants, including 110 males and 90 females in Shiraz (Iran), to investigate the relationship between chronic exposure to metals and ROS damage by analyzing malondialdehyde (MDA) and 8-Oxo-2'-deoxyguanosine (8-OHdG) concentrations, and has evaluated the associations between chronic metal exposure and ROS damage using regression analysis. Our findings showed participants are chronically exposed to elevate As, Ni, Hg, and Pb levels. The mean urinary concentrations of 8-OHdG and MDA were 3.8 ± 2.35 and 214 ± 134 µg/g creatinine, respectively. This study shows that most heavy metals are correlated with urinary ROS biomarkers (R ranges 0.19 to 0.64). In addition, regression analysis accounting for other confounding factors such as sex, age, smoking status, and teeth filling with amalgam highlights that Al, Cu, Si and Sn are associated with 8-OHdG concentrations, while an association between Cr and MDA and 8-OHdG is suggested. Smoking cigarettes and water-pipe is considered a significant contributory factor for both ROS biomarkers (MDA and 8-OHdG).

Blubber Cortisol-Based Approach to Explore the Endocrine Responses of Indo-Pacific Humpback Dolphins (Sousa chinensis) to Diet Shifts and Contaminant Exposure

The detrimental effects of contaminant exposure and changes in the availability of food resources are still of concern for Indo-Pacific humpback dolphins (Sousa chinensis) of the Pearl River Estuary (PRE). Here, we validated and applied a blubber cortisol biomarker approach to assess the physiological responses of PRE dolphins to various pollutants and diet changes during 2008-2018 (n = 70). For calves, generalized additive models (GAMs) revealed that cortisol levels varied significantly by month and were positively correlated with the body length, owing to significant maternal transfer of hormones. The significantly positive correlation between length-adjusted cortisol levels in calf and the annual calf mortality ratios suggested that during years of high calf mortality, these animals were highly stressed before they die. For noncalves, blubber cortisol levels in diseased animals were significantly higher than those in "healthy" ones. Chromium (Cr) and dichlorodiphenyltrichloroethanes displayed a significant and positive relationship with blubber cortisol levels, suggesting that contaminant-mediated endocrine disruption effects may have occurred in noncalves. The GAMs indicated a decreasing trend of noncalf's blubber cortisol levels over an 11-year span, which can be explained by their declining contaminant accumulation levels due to a significant dietary shift from eating highly contaminated fishes to less polluted ones.

A review of the endocrine disrupting effects of micro and nano plastic and their associated chemicals in mammals

Over the years, the vaste expansion of plastic manufacturing has dramatically increased the environmental impact of microplastics [MPs] and nanoplastics [NPs], making them a threat to marine and terrestrial biota because they contain endocrine disrupting chemicals [EDCs] and other harmful compounds. MPs and NPs have deleteriouse impacts on mammalian endocrine components such as hypothalamus, pituitary, thyroid, adrenal, testes, and ovaries. MPs and NPs absorb and act as a transport medium for harmful chemicals such as bisphenols, phthalates, polybrominated diphenyl ether, polychlorinated biphenyl ether, organotin, perfluorinated compounds, dioxins, polycyclic aromatic hydrocarbons, organic contaminants, and heavy metals, which are commonly used as additives in plastic production. As the EDCs are not covalently bonded to plastics, they can easily leach into milk, water, and other liquids affecting the endocrine system of mammals upon exposure. The toxicity induced by MPs and NPs is size-dependent, as smaller particles have better absorption capacity and larger surface area, releasing more EDC and toxic chemicals. Various EDCs contained or carried by MPs and NPs share structural similarities with specific hormone receptors; hence they interfere with normal hormone receptors, altering the hormonal action of the endocrine glands. This review demonstrates size-dependent MPs' bioaccumulation, distribution, and translocation with potential hazards to the endocrine gland. We reviewed that MPs and NPs disrupt hypothalamic-pituitary axes, including the hypothalamic-pituitary-thyroid/adrenal/testicular/ovarian axis leading to oxidative stress, reproductive toxicity, neurotoxicity, cytotoxicity, developmental abnormalities, decreased sperm quality, and immunotoxicity. The direct consequences of MPs and NPs on the thyroid, testis, and ovaries are documented. Still, studies need to be carried out to identify the direct effects of MPs and NPs on the hypothalamus, pituitary, and adrenal glands.

The changes of essential trace elements in residents from an e-waste site and the relationships between elements and hormones of the hypothalamic-pituitary-thyroid (HPT) axis

The heavy metals pollution and related health issues were widely reported in e-waste sites, while the impacts of e-waste exposure on the essential trace elements have been neglected. The aim of this study was focused on the internal Cu, Fe, Mn and Zn levels in the residents from an e-waste site and the potential endocrine disrupting effects of these essential trace elements on the hypothalamic-pituitary-thyroid (HPT) axis. This was a cross-sectional study that 87 subjects were recruited from the e-waste site and 81 from the reference site. The results indicated that the e-waste exposed group had significantly lower Fe, Mn level when compared with the reference group (p < 0.05). Cu and Zn were also lower in the exposed group but the differences were not statistically significant. The exposed group had significantly higher TSH level and Fe was significantly associated with TSH in the females (β (95% CI): - 1.892 (-3.309, -0.475), p = 0.009), rather than in males or all subjects. The exposed group also showed oxidative stress which was indicated by the increased concentrations of MDA and 8-iso-PG. It was further indicated the elevated MDA was mediated by the increase of TSH in the females but not directly related to Fe. In conclusion, the e-waste exposed group showed a decrease of essential trace elements, an increase of TSH and oxidative stress. The decreased Fe was related to the elevated TSH in the females, which further indirectly mediated the increase of oxidative stress. The results suggested that the internal exposure levels and the potential health effects of the essential trace elements in populations from e-waste sites should be of more concern. And the women might be more vulnerable and they need more protection to against the adverse health effects from e-waste.

Molecular Mechanism of Arsenic-Induced Neurotoxicity including Neuronal Dysfunctions

Arsenic is a key environmental toxicant having significant impacts on human health. Millions of people in developing countries such as Bangladesh, Mexico, Taiwan, and India are affected by arsenic contamination through groundwater. Environmental contamination of arsenic leads to leads to various types of cancers, coronary and neurological ailments in human. There are several sources of arsenic exposure such as drinking water, diet, wood preservatives, smoking, air and cosmetics, while, drinking water is the most explored route. Inorganic arsenic exhibits higher levels of toxicity compared its organic forms. Exposure to inorganic arsenic is known to cause major neurological effects such as cytotoxicity, chromosomal aberration, damage to cellular DNA and genotoxicity. On the other hand, long-term exposure to arsenic may cause neurobehavioral effects in the juvenile stage, which may have detrimental effects in the later stages of life. Thus, it is important to understand the toxicology and underlying molecular mechanism of arsenic which will help to mitigate its detrimental effects. The present review focuses on the epidemiology, and the toxic mechanisms responsible for arsenic induced neurobehavioral diseases, including strategies for its management from water, community and household premises. The review also provides a critical analysis of epigenetic and transgenerational modifications, mitochondrial oxidative stress, molecular mechanisms of arsenic-induced oxidative stress, and neuronal dysfunction.

E-Waste in Africa: A Serious Threat to the Health of Children

Waste electronic and electrical equipment (e-waste) consists of used and discarded electrical and electronic items ranging from refrigerators to cell phones and printed circuit boards. It is frequently moved from developed countries to developing countries where it is dismantled for valuable metals in informal settings, resulting in significant human exposure to toxic substances. E-waste is a major concern in Africa, with large sites in Ghana and Nigeria where imported e-waste is dismantled under unsafe conditions. However, as in many developing countries, used electronic and electrical devices are imported in large quantities because they are in great demand and are less expensive than new ones. Many of these used products are irreparable and are discarded with other solid waste to local landfills. These items are then often scavenged for the purpose of extracting valuable metals by heating and burning, incubating in acids and other methods. These activities pose significant health risks to workers and residents in communities near recycling sites. E-waste burning and dismantling activities are frequently undertaken at e-waste sites, often in or near homes. As a result, children and people living in the surrounding areas are exposed, even if they are not directly involved in the recycling. While toxic substances are dangerous to individuals at any age, children are more vulnerable as they are going through important developmental processes, and some adverse health impacts may have long-term impacts. We review the e-waste situation in Africa with a focus on threats to children's health.

Association Between Rare Earth Element Cerium and the Risk of Oral Cancer: A Case-Control Study in Southeast China

Cerium (Ce), the most abundant of rare earth elements in the earth's crust, has received much health concerns due to its wide application in industry, agriculture, and medicine. The current study aims to evaluate whether there is an association between Ce exposures and the risk of developing oral cancer. Serum Ce level of 324 oral cancer patients and 650 matched healthy controls were measured by inductively coupled plasma mass spectrometry. Association between Ce level and the risk of oral cancer was estimated with an unconditional logistic regression model. Serum Ce concentrations in the oral cancer patients and controls were 0.57 (0.21-3.02) μg/L and 2.27 (0.72-4.26) μg/L, respectively. High level of Ce was associated with a decreased risk of oral cancer (OR: 0.60, 95% CI: 0.43-0.84). Stronger inverse associations between high level of Ce and oral cancer risk were observed among those with smoking (OR: 0.46, 95% CI: 0.27-0.79), drinking (OR: 0.50, 95% CI: 0.26-0.96), limited intake of leafy vegetables (OR: 0.40, 95% CI: 0.22-0.71) and fish (OR: 0.52, 95% CI: 0.33-0.83). There were significant multiplicative interactions between Ce level and alcohol drinking or intake of leafy vegetables and fish (all P_interaction <0.05). This preliminary case-control study suggests an inverse association between high serum Ce level and the risk of oral cancer. Further prospective studies with a larger sample size are needed to confirm the findings.