Associations between arsenic, cadmium, and selenium exposure and oxidative stress in rural residents of northern Laos

Abstract

BACKGROUND AND AIM: Oxidative stress is an important consequence of exposure to arsenic and cadmium, but it is unclear to what extent low-level exposures contribute to oxidative stress. Additionally, previous studies suggested that selenium suppresses the toxicity of arsenic and cadmium. This study aimed to examine associations between arsenic and cadmium exposure and oxidative damage to DNA and lipid in rural residents of northern Laos, considering selenium interactions with the two toxic elements. METHODS: We collected data on general characteristics (village, sex, age, smoking, drinking, height, and weight) and a single spot urine sample from the participants (n = 341). Urinary concentrations of arsenic, cadmium, and selenium were measured by inductively coupled plasma mass spectrometry to estimate their exposure/intake levels. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-isoprostane concentrations were measured by liquid chromatography-tandem mass spectrometry (oxidative stress biomarkers of DNA and lipid, respectively). Multiple linear regression analyses examined associations of urinary concentrations of arsenic and cadmium with those of oxidative stress markers, adjusted for covariates. We performed additional analyses to include interaction terms between urinary concentrations of arsenic/cadmium and selenium. RESULTS:Geometric means of specific gravity-adjusted urinary concentrations of arsenic, cadmium, selenium, 8-OHdG, and 8-isoprostane were 40.0, 1.38, 11.7, 3.89, and 0.934 µg/L, respectively. Urinary concentration of arsenic and cadmium showed positive associations with that of 8-isoprostane. We also observed that there were significant interactions between arsenic and selenium in the association with 8-OHdG (Coefficient (95% CI) = -0.21 (-0.37, -0.05)) and between cadmium and selenium in the association with 8-isoprostane (Coefficient (95% CI) = -0.14 (-0.25, -0.03)). CONCLUSIONS:Our findings suggested that arsenic and cadmium exposure were positively associated with oxidative stress in rural residents of northern Laos. Additionally, selenium might have protective effects on arsenic-/cadmium-induced oxidative stress. KEYWORDS: Heavy metals, Chemical exposures, Environmental epidemiology