Objective: To evaluate the effect of nitrate levels in the drinking water on the incidence of urological malignancies in a German community.
Patients and methods: For 28 years (1957-86) the community of Bocholt, Germany (70,000 inhabitants) had a drinking water supply with different nitrate levels, i.e. 60 mg/L in group A (57,253 inhabitants) and 10 mg/L in group B (10,037 inhabitants). All newly diagnosed cases of urological malignancies were registered from 1986 to 1997. The incidence was calculated using an age standardization based on the German population.
Results: In all, there were 527 urological malignancies recorded (urothelial cancer 39.8%, renal cell carcinoma 10.8%, testicular tumours 8.0%, penile carcinoma 1.7%, prostate cancer 39.7%). The incidence per 100,000 inhabitants/year of urinary tract tumours was 33.8 in group A and only 17.1 in group B (relative risk, RR 1.98, 95% confidence interval, CI, 1.10-3.54). The RR was 0.87 (0.34-2.22) for renal tumours, 0.66 (0.14-2.88) for penile cancer and 1.06 (0.76-1.48) for prostate cancer. For testicular tumours there was an inverse association with nitrate level, with a RR of 0.43 (0.21-0.90).
Conclusion: This study showed an association of nitrate load in drinking water and the incidence of urothelial cancer in both genders, with an inverse correlation to testicular tumours and no correlation with renal, penile and prostatic tumours.