Although the exposure levels of lead and cadmium we are exposed today are significantly lower than in the past, environmental exposure to low levels of both metals accumulate in the body and could develop various chronic diseases. Some epidemiological studies recently have shown a positive association of low dose exposure of lead and cadmium with the adverse effects on nervous and endocrine systems. However, there have been few studies on ototoxicity and endocrine disturbance, which are representative effects on the nervous and endocrine systems. Most previous research on these effects of lead and cadmium has been limited to occupationally high exposed workers and relatively vulnerable children and youth. Therefore, it is important in public health to study these two effects (ototoxicity and endocrine disorders) based on the general population exposed to environmental lead and cadmium.This study aims to investigate the associations of environmental lead and cadmium exposure with the ototoxic effect and endocrine disorder among the general population of Korea. Because this study is cross-sectional, I used data that could represent the general population of Korea and considered various potential confounders in the models to minimize the bias of the results. I analyzed the data from the Korea National Health and Nutrition Examination Survey (KNHANES), which is an ongoing series of cross-sectional surveys designed to assess health and nutritional status in the non-institutionalized Korean population.I found that environmental lead and cadmium exposure could reduce hearing ability at high-frequencies, and the estimating method of hearing disorder using the relatively low frequencies could underestimate the hearing impairments caused by ototoxic effects. This thesis also supports the hypothesis that low dose exposure to lead could affect metabolic syndrome and thyroid hormone. A significant association between blood lead levels and metabolic syndrome was observed in the general population of Korea, and serum thyroid-stimulating hormone levels were both positively associated with blood lead concentrations and metabolic syndrome. Moreover, I found that environmental lead exposure was positively associated with menstrual irregularity and early menopause in Korean women. In particular, the effect of lead on menstrual irregularity increased in the context of higher cadmium levels.Overall, this thesis provides evidence that environmental lead and cadmium exposures are associated with the ototoxic effect and endocrine disorders. This finding provides preliminary evidence for public health strategies to prevent hearing loss and diseases caused by endocrine-disrupting.