What adverse health effects will environmental heavy metal co-exposure bring us: based on a biological monitoring study of sanitation workers

Abstract

To investigate the relationship between health effect profile and co-exposure to heavy metal, 254 sanitation workers from Guangzhou, China, were recruited. Ten urinary metals were determined by inductively coupled plasma mass spectrometry. Parameters of physical examination, including blood lipid metabolism, renal function, blood pressure, and lung function, were tested for each participant. The hazard quotients (HQs) of eight heavy metals were evaluated. Cobalt, copper (Cu), molybdenum (Mo), nickel (Ni), and tin (Sn) demonstrated the top five associations with human health with the ∑₁₉β as 2.220, 1.351, 1.234, 0.957, and 0.930, respectively. Most physical examination parameters of workers were under the normal ranges, except the levels of forced mid expiratory flow rate (MMEF_75/25), the maximum expiratory flow rate at 25% vital capacity (MEF₂₅) and apolipoprotein B in the first quartile, and the level of uric acid in the third quartile of sanitation works. Moreover, Cu was significantly associated with diastolic pressure, pulse, and high density lipid (p < 0.05). Each unit increase in Mo level was related to a 120% increase odd ratio (OR) of abnormal of systolic pressure, but was significantly and negatively correlated with high density lipoprotein and apolipoprotein A, suggesting that Mo exposure may be a risk factor of cardiovascular disease. Each unit increase in Ni and Sn levels was associated with an increased OR of abnormal rate of MMEF_75/25 and MEF₂₅ (p < 0.001), suggesting the increasing risks of respiratory diseases. Sanitation workers exposed to Ni and Pb alone had no carcinogenic risks (HQ < 1). However, 23.8%, 34.6%, and 87.3% of sanitation workers confronted non-carcinogenic risks when exposed to Cu, Mo alone (HQ > 1), or co-exposed to the four heavy metals (HI > 1). Our study preliminarily revealed the potential sensitive health indicators of heavy metal co-exposure, which will provide beneficial health protection suggestions for the occupational populations.

Keywords: Blood pressure; Lipid metabolism; Lung function; Metal exposure; Risk assessment.