Distribution and Determinants of Urinary Cadmium Levels in Korean Women: Focused Analysis on Age and Smoking using the 4th KoNEHS Data

Background: Cadmium is a toxic heavy metal with an exceptionally long biological half-life, leading to significant cumulative exposure.This study characterized urinary cadmium (U-Cd) distribution in Korean adults, with a specific focus on identifying high-exposure patterns and determinants among women using nationally representative biomonitoring data.Methods: Creatinine-corrected U-Cd levels were analyzed in 4,239 adults from the 4th Korea National Environmental Health Survey (KoNEHS).Weighted analyses were applied to account for the complex survey design.High exposure was defined as U-Cd levels at or above the 90th percentile (P90) and 95th percentile (P95).Smoking exposure was objectively assessed using urinary cotinine concentrations rather than self-reported data.Results: The weighted median U-Cd was 0.64 g/g creatinine, with P90 and P95 at 1.51 and 1.97 g/g creatinine, respectively.The high-exposure group (P90) was significantly older and predominantly female (84.2%), while their urinary cotinine levels were paradoxically lower than those in the non-high-exposure group.In weighted regression models specifically for women, age showed a significant positive association with U-Cd ( = 0.042, p < 0.001), whereas urinary cotinine showed no significant association (p = 0.615).Conclusions:These findings indicate that U-Cd primarily reflects long-term cumulative environmental exposure rather than short-term smoking behavior, a trend that is particularly evident in the female population.Targeted exposure reduction strategies should prioritize older women as a high-risk group for chronic cadmium accumulation.