27. 由于未受辐射的人群中的心血管病发生率高，该疾病具有多因子特点和异质性，以及需要说明一些重要的混杂因素（如吸烟、遗传和胆固醇水平），因此仅靠流行病学研究是否能大大提高对心血管病发生率和辐射照射之间存在因果关系的可能性及这种关系性质的了解，目前尚不确定。
27. Because of the high occurrence of cardiovascular disease in non-exposed populations, and its multifactorial nature and heterogeneity, as well as the need to account for major confounding factors (such as tobacco use, genetics and cholesterol level), it is uncertain whether epidemiological studies alone will be able to add significantly to the understanding of the potential for and nature of any possible causal relationship between the incidence of cardiovascular disease and radiation exposure.