Associations of long-term cadmium exposure with peripheral white blood cell subtype counts and indices in residents of cadmium-polluted areas

Abstract

BackgroundExperimental evidence suggests that exposure to cadmium (Cd) could affect immune cells in vivo and in vitro. However, the associations of long-term Cd exposure with white blood cell (WBC) subtype counts and hemogram-derived indices have been rarely investigated. Therefore, we evaluated these relationships in residents of cadmium-polluted areas. MethodsThis cross-sectional study included 431 participants aged 45–75 years without occupational exposure histories from Cd-contaminated areas of southern China. We detected WBC, neutrophil, lymphocyte, and monocyte counts using routine blood tests and calculated neutrophil–lymphocyte ratio (NLR), systemic inflammation response index (SIRI), and lymphocyte–monocyte ratio (LMR). Urinary Cd (U–Cd) was measured with inductively coupled plasma mass spectrometry and adjusted for creatinine. To evaluate the associations of U–Cd with peripheral WBC subtype counts and indices, we performed multivariate linear regression, logistic regression and subgroup analyses using U–Cd categorized into quartiles. ResultsIn models adjusted for all potential confounders, U–Cd was negatively associated with WBC, neutrophil, and monocyte counts in Q2, compared with Q1 of U–Cd (p < 0.05). A similar relationship was observed between U–Cd and NLR and SIRI, whereas the corresponding association for LMR was positive (p < 0.05). In subgroup analyses, U–Cd was negatively associated with neutrophil count, except for never smokers, after full adjustment. ConclusionsU–Cd was negatively associated with WBC count, neutrophil count, monocyte count, NLR, and SIRI, and positively associated with LMR. Therefore, neutrophil count could be a potential indicator of long-term Cd exposure-associated immunosuppressive effect.