Unchanged Pulmonary Function and Increased Prevalence of Subjective Respiratory Symptoms in Non-smoking Workers with Low Cadmium Body Burden

The study investigated the effects of low cadmium (Cd) burden on the respiratory symptoms and pulmonary function in occupational workers. The study population consisted of 98 nickel-cadmium battery workers. Levels of urine cadmium, urinary creatinine (Cr), and data on the adverse respiratory symptoms and pulmonary function of the participants were measured and collected respectively. The urinary cadmium level in cadmium-exposed workers (n = 53) was within the normal range but greater than 2.4 times than those of the control group (n = 45). Compared with the control group, the cadmium-exposed workers had higher prevalence of all subjective respiratory symptoms studied in the study. The prevalence of cough (30%), phlegm (23%), and upper respiratory tract infection (URTI) (79%) in the exposure group was significantly (P < 0.05) higher than the prevalence of cough (11%), phlegm (7%), and URTI (31%) in the control group respectively. There was no significant difference between the Cd-exposed workers and control group in pulmonary function test. Our findings suggested that adverse subjective respiratory symptoms were increased and pulmonary function were unchanged in low Cd burden workers. Unchanged pulmonary function may be related to age, exposure duration, and distribution of Cd in tissue. These workers need to continue being monitored in longitudinal studies.