Factors associated with blood zinc, chromium, and lead concentrations in residents of the Nam Pong River in Thailand

This cross-sectional analytical study aimed to determine the blood levels of zinc (B-Zn), chromium (B-Cr), and lead (B-Pb) and to identify the factors influencing these levels in the blood of residents of the Nam Pong River. Quantitative data collection was utilized, and systematic random sampling was conducted to obtain 420 samples for measuring serum heavy metals, including B-Zn, B-Cr, and B-Pb. Multiple regression analysis was used to identify factors influencing the accumulation of heavy metals in the population, reported mean differences, 95% confidence intervals, and p values. The average levels of heavy metals were 74.38 +/- 14.00 mu g/dL (95% confidence interval [CI]: 73.03-75.72) for zinc, 0.28 +/- 0.23 mu g/L (95% CI: 0.26-0.30) for chromium, and 2.80 +/- 1.60 mu g/dL (95% CI: 2.64-2.95) for lead, which all were within normal limits. Factors influencing zinc levels included occupational exposure (batteries) (mean diff = 11.56; 95% CI: 1.81-21.32, p value = 0.02) and consumption of fish from the river exceeding 300 grams/meal or three times/week (mean diff = 4.68; 95% CI: 0.09-9.45, p value = 0.05). Factors influencing chromium levels included a history of past illness (mean diff = 0.19; 95% CI: 0.05-0.34, p value = 0.01) and dust/chemical exposure from industry (mean diff = 0.05; 95% CI: 0.00-0.11, p value = 0.05). Factors influencing lead concentrations included gender (mean diff = 1.82; 95% CI: 0.26-1.98, p value = 0.001), smoking (mean diff = 1.03; 95% CI: 0.60-1.45, p value < 0.001), and occupational exposure (garage) (mean diff = 1.11; 95% CI: 0.27-1.94, p value = 0.01).