Jemal Ahmedin, Graubard Barry I, Devesa Susan S, Flegal Katherine M
Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland, USA.
Environ Health Perspect. 2002 Apr;110(4):325-9. doi: 10.1289/ehp.02110325.
Lead is classified as a possible carcinogen in humans. We studied the relationship of blood lead level and all cancer mortality in the general population of the United States using data from the National Health and Nutrition Examination Survey II (NHANES II) Mortality Study, 1992, consisting of a total of 203 cancer deaths (117 men and 86 women) among 3,592 whites (1,702 men and 1,890 women) with average of 13.3 years of follow-up. We used Cox proportional hazard regression models to estimate the dose-response relationship between blood lead and all cancer mortality. Log-transformed blood lead was either categorized into quartiles or treated as a continuous variable in a cubic regression spline. Relative risks (RRs) were estimated for site-specific cancers by categorizing lead above and below the median. Among men and women combined, dose-response relationship between quartile of blood lead and all cancer mortality was not significant (ptrend = 0.16), with RRs of 1.24 [95% percent confidence interval (CI), 0.66-2.33], 1.33 (95% CI, 0.57-3.09), and 1.50 (95% CI, 0.75-3.01) for the second, third, and fourth quartiles, respectively, compared with the first quartile. Spline analyses found no dose response (p = 0.29), and none of the site-specific cancer RRs were significant. Among men, no significant dose-response relationships were found for quartile or spline analyses (p trend = 0.57 and p = 0.38, respectively). Among women, no dose-response relationship was found for quartile analysis (ptrend = 0.22). However, the spline dose-response results were significant (p = 0.001), showing a threshold effect at the 94th percentile of blood lead or a lead concentration of 24 microg/dL, with an RR of 2.4 (95% CI, 1.1-5.2) compared with the risk at 12.5 percentile. Because the dose-response relationship found in women was not found in men, occurred at only the highest levels of lead, and has no clear biologic explanation, further replication of this relationship is needed before it can be considered believable. In conclusion, individuals with blood lead levels in the range of NHANES II do not appear to have increased risk of cancer mortality.
铅被归类为对人类可能的致癌物。我们利用1992年美国国家健康与营养检查调查II（NHANES II）死亡率研究的数据，研究了美国普通人群中血铅水平与所有癌症死亡率之间的关系。该研究共有3592名白人（1702名男性和1890名女性），平均随访13.3年，其中共有203例癌症死亡（117名男性和86名女性）。我们使用Cox比例风险回归模型来估计血铅与所有癌症死亡率之间的剂量反应关系。对数转换后的血铅要么被分为四分位数，要么在三次回归样条中作为连续变量处理。通过将铅分为中位数以上和以下，估计特定部位癌症的相对风险（RRs）。在男性和女性的综合数据中，血铅四分位数与所有癌症死亡率之间的剂量反应关系不显著（p趋势=0.16），与第一四分位数相比，第二、第三和第四四分位数的RRs分别为1.24[95%置信区间（CI），0.66 - 2.33]、1.33（95%CI，0.57 - 3.09）和1.50（95%CI，0.75 - 3.01）。样条分析未发现剂量反应（p = 0.29），且特定部位癌症的RRs均不显著。在男性中，四分位数或样条分析均未发现显著的剂量反应关系（p趋势分别为0.57和p = 0.38）。在女性中，四分位数分析未发现剂量反应关系（p趋势=0.22）。然而，样条剂量反应结果显著（p = 0.001），显示在血铅第94百分位数或铅浓度为24微克/分升时存在阈值效应，与第12.5百分位数的风险相比，RR为2.4（95%CI，1.1 - 5.2）。由于在女性中发现的剂量反应关系在男性中未发现，仅发生在铅的最高水平，且没有明确的生物学解释，因此在该关系被认为可信之前，需要进一步重复验证。总之，血铅水平在NHANES II范围内的个体似乎没有增加癌症死亡风险。
