ENVIRONMENTAL EXPOSURE TO CADMIUM, ZINC AND SELENIUM AND RISK OF PROSTATE DISEASE

Abstract

Introduction Prostate cancer is the third most common cancer diagnosed and the leading cause of cancer deaths in New Zealand men, with a significant differential by ethnic group. Ethnicity influences human interaction with the environment through culturally specific occupation and diet. The interface of ethnicity and environmental health and its role in causing differential rates of prostate disease is still unknown. Our study examined putative environmental factors for elevated serum prostate specific antigen (PSA) (a correlate of prostate cancer) and benign prostatic hyperplasia. Cadmium (Cd), an industrial/agricultural bi-product and suspected prostate carcinogen, is readily found in the New Zealand soil/food supply. Zinc (Zn) is a nutrient element necessary for healthy prostate function. These two metal ions compete for binding sites in tissues and Zn antagonises the toxicity of Cd. The role of selenium (Se) as a promising anti carcinogen for prostate cancer is being researched. Zn and Se are of particular interest in New Zealand, as soil levels are low compared to other countries. Objective To examine environmental exposure to Cd, Zn and Se in three New Zealand ethnic groups and explore associations with elevated PSA levels and prostate disease. Methods Fourteen hundred subjects have been tested for elevated PSA and further diagnosed for benign prostatic hyperplasia (BPH). From these subjects, 70 randomly selected bloods from each main ethnic group (European, Maori and Pacific Island) were tested for Cd, Se and Zn using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), and a risk factor/exposure questionnaire administered. Ethnic blood levels of Cd, Zn and Se levels have been compared along with the serum PSA levels, symptoms of BPH, occupational and dietary data. Results: There is an ethnic difference in blood levels of the metals examined. The overall mean blood levels of Cd are consistent with the results of a Belgium study of subjects deemed to have high environmental Cd exposure. Conclusions Results indicate that it is likely that environmental exposure to Cd, Zn and Se differs between ethnic groups in New Zealand and that this may be an important factor in the differential rates of prostate disease between the ethnic groups.