Forman D
Imperial Cancer Research Fund, Radcliffe Infirmary, Oxford.
Cancer Surv. 1989;8(2):443-58.
This article focuses on the relationship between exposure to nitrates in the environment and subsequent risk of human cancer. The question of whether or not nitrates represent a cancer hazard is one of the most important public health issues arising from research into N-nitroso compounds. The reason for concern results from the endogenous reduction of nitrate to nitrite and subsequent nitrosation of amines, amides and proteins to give rise to carcinogenic N-nitroso compounds. The human evidence relating nitrate exposure to cancer, especially gastric cancer, has been largely based on geographic correlation studies, a relatively weak form of epidemiological methodology. In sum, this evidence and that from a small number of individually based studies does not support the hypothesis of a straightforward cause and effect association between nitrate exposure and cancer risk. Because many other factors besides nitrate are involved in the endogenous formation of N-nitrosation compounds, it is possible that exposure to nitrate is not a rate-limiting factor in most circumstances. This makes the setting of regulatory standards for nitrate exposure from the environment a complex issue.
本文聚焦于环境中硝酸盐暴露与人类后续患癌风险之间的关系。硝酸盐是否构成癌症危害这一问题，是对N-亚硝基化合物研究中出现的最重要的公共卫生问题之一。令人担忧的原因在于硝酸盐会内源性还原为亚硝酸盐，随后亚硝酸盐会使胺类、酰胺类和蛋白质发生亚硝化反应，从而产生致癌性N-亚硝基化合物。关于硝酸盐暴露与癌症（尤其是胃癌）之间关系的人体证据，很大程度上基于地理相关性研究，这是一种相对较弱的流行病学方法形式。总之，这些证据以及少数基于个体的研究结果并不支持硝酸盐暴露与癌症风险之间存在直接因果关联的假设。由于除硝酸盐外，许多其他因素也参与了N-亚硝化化合物的内源性形成过程，所以在大多数情况下，硝酸盐暴露可能并非限速因素。这使得制定环境中硝酸盐暴露的监管标准成为一个复杂的问题。
