本文讨论了在流行病学研究中,影响剂量一反应关系的某些时间因素,如接触年龄、接触年限和停止接触年限以及它们之间的相互关系。接触年龄青年人和成年人对疾病的敏感性是不同的。研究表明,铅对大脑的影响,儿童较成年人敏感;年轻时开始吸烟者,肺癌发生的相对危险度显著高于成年开始吸烟者。本文表明接触年龄与疾病发生的危险度密切相 This article discusses some of the time-related factors that influence the dose-response relationship in epidemiological studies, such as age of exposure, duration of exposure, duration of exposure, and their interrelationships. Young people and adults exposed to the age sensitivity of the disease is different. Studies have shown that the impact of lead on the brain, children are more sensitive than adults; young smokers started, the relative risk of lung cancer was significantly higher than that of adult smokers. This article shows that exposure to age is closely related to the risk of disease