Heavy metal exposure and renal impairment: A systematic review of observational studies

Background: Environmental exposure to toxins has been strongly implicated in its multi-faceted etiology of chronic kidney disease, a serious public health problem affecting individuals, families, and communities. There is a need to synthesize available studies on the effect of heavy metal exposure on renal function, considering the rising global burden of kidney disease. The objective of this study is to determine the association between exposure to heavy metals and renal disease. Methods: The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) were used to conduct the review. A comprehensive independent search, title, abstract, and full-text screening of available literature on Google Scholar, PubMed, and OAREScience was done between March 2021 and May 2021. The criteria for study inclusion were full-text articles published in English language in the last 20 years (2001-2020), and observational primary human studies reporting the association between heavy metal exposure and renal disease. The Newcastle-Ottawa Quality Assessment Scale was used to assess the quality of the included studies. Results: A total of 552 studies were identified following the search from the different databases. A total of 13 studies were finally included in the review. Heavy metals implicated in the studies include cadmium, lead, mercury, and arsenic, with ten studies showing environmental exposure as the primary source. Ten (10) studies showed an association between heavy metal exposure and renal impairment (p<0.05) while only 3 studies reported no association. Conclusion: Environmental monitoring is needed to stem the tide of heavy metal exposure in view of the growing burden of chronic kidney disease.

Health risk and spatial distribution characteristics of heavy metal exposure in typical abandoned mining area in Liuzhou, Guangxi / 环境与职业医学

Background Exposure to heavy metals has potential adverse impacts on human health, and the concentration of heavy metals in abandoned mining areas may still be higher than that in general areas, so the health risk assessment in such areas cannot be ignored. Objective To explore the health risk of heavy metal exposure and the spatial distribution characteristics of associated main metals in a typical abandoned mining area. Methods Environmental samples of irrigated soil, rice, and drinking water were collected from 13 natural villages under the jurisdiction of a township in Liuzhou, Guangxi from November to December 2019, where a typical abandoned mining was located. Finally, 13 irrigation soil samples, 11 rice samples, and 13 drinking water samples were collected. The concentrations of six metals and metalloid elements in each environmental sample were detected by inductively coupled-plasma mass spectrometry (ICP-MS), including cadmium (Cd), arsenic (As), lead (Pb), chromium (Cr), copper (Cu), and zinc (Zn). At the same time, 251 local residents were recruited for health risk assessment. Model parameters such as body weight, rice intake, and drinking water intake of local residents were obtained through field survey, and the median metal concentration of each environmental sample was taken as the risk assessment parameter of the region. The health risk of heavy metal exposure of local residents was assessed by using oral health risk assessment model of U.S. Environmental Protection Agency. The spatial distribution characteristics of health risks associated with heavy metals were evaluated by empirical Bayes interpolation method using Geographic Information System (GIS) technology. Results The positive rates of Cd, As, Pb, Cr, Cu, and Zn in the irrigated soil samples were 100.00%. The positive rate of Pb was 63.64% in the rice samples, while the rates of other metals were 100.00%. The positive rates of Cd, As, Pb, Cr, Cu, and Zn in the drinking water samples were 53.85%, 76.92%, 92.31%, 15.38%, 84.62%, and 100.00%, respectively. The results of non-carcinogenic risk assessment of oral exposure to heavy metals suggested that the contribution of heavy metals causing non-carcinogenic risk from high to low was As (70.52%) > Cd (18.03%) > Zn (6.63%) > Cu (4.12%) > Pb (0.64%) > Cr (0.06%), and the corresponding estimated non-carcinogenic risk values were 3.54 × 100, 9.05 × 10−1, 3.33 × 10−1, 2.07 × 10−1, 3.23 × 10−2, and 5.42 × 10−4, respectively. The results of carcinogenic risk assessment of oral exposure to heavy metals suggested that the contribution of studied metals from high to low was Cd (87.00%) > As (10.24%) > Cr (2.60%) > Pb (0.16%), and the estimated carcinogenic risks were 4.35× 10−3, 5.12 × 10−4, 1.30 × 10−4, and 3.08 × 10−7, respectively. Rice was the leading media associated with non-carcinogenic risk and carcinogenic risk (99.4% and 99.8% respectively). The spatial distribution characteristics of GIS showed no obvious regularity in the distribution of As in irrigated soil, rice, and drinking water. In rice and irrigated soil, the content of Cd in the villages adjacent to the mining area was obviously higher than that in the other villages, while in drinking water, the content in the villages far away from the mining area was higher. Conclusion As and Cd are the main heavy metals that increase the health risk of local residents in a typical abandoned mining area, and the distribution characteristics of the two heavy metals in different environmental media are not completely consistent.

Association between metal cobalt exposure and the risk of congenital heart defect occurrence in offspring: a multi-hospital case-control study

BACKGROUND@#Many studies have investigated heavy metal exposure could increase the occurrence of congenital heart defects (CHDs). However, there are limited data regarding the relationship between cobalt exposure and CHD occurrence in offspring. The aim of this study was to analyze the association between cobalt exposure in mothers and the risk of CHDs in offspring.@*MATERIALS AND METHODS@#In order to explore the association between cobalt exposure and occurrence of congenital heart defect (CHD), a case-control study with 490 controls and 399 cases with CHDs in China were developed. The concentrations of cobalt in hair of pregnant woman and fetal placental tissue were measured and processed by a logistic regression analysis to explore the relationship between cobalt exposure and risk of CHDs.@*RESULTS@#The median concentration of hair cobalt in the control and case group was 0.023 ng/mg and 0.033 ng/mg (aOR, 1.837; 95% CI, 1.468-2.299; P < 0.001), respectively. And the median (5-95% range) fetal placental cobalt concentrations were 19.350 ng/g and 42.500 ng/g (aOR, 2.924; 95% CI, 2.211-3.868; P < 0.001) in the control and case groups, respectively. Significant differences in the middle level of cobalt in hair were found in the different CHD subtypes, including septal defects, conotruncal defects, right ventricular outflow tract obstruction, and left ventricular outflow tract obstruction (P < 0.001). Dramatically, different cobalt concentrations in fetal placental tissue were found in all subtypes of cases with CHDs (P < 0.01).@*CONCLUSIONS@#The finding suggested that the occurrence of CHDs may be associated with cobalt exposure.