Enstrom James E
Jonsson Comprehensive Cancer Center, University of California, Los Angeles, California 90095, USA.
Inhal Toxicol. 2005 Dec 15;17(14):803-16. doi: 10.1080/08958370500240413.
Fine particulate air pollution has been associated with increases in long-term mortality in selected cohort studies, and this association has been influential in the establishment of air quality regulations for fine particles (PM(2.5)). However, this epidemiologic evidence has been questioned because of methodological issues, conflicting findings, and lack of an accepted causal mechanism. To further evaluate this association, the long-term relation between fine particulate air pollution and total mortality was examined in a cohort of 49, 975 elderly Californians, with a mean age of 65 yr as of 1973. These subjects, who resided in 25 California counties, were enrolled in 1959, recontacted in 1972, and followed from 1973 through 2002; 39, 846 deaths were identified. Proportional hazards regression models were used to determine their relative risk of death (RR) and 95% confidence interval (CI) during 1973-2002 by county of residence. The models adjusted for age, sex, cigarette smoking, race, education, marital status, body mass index, occupational exposure, exercise, and a dietary factor. For the 35, 789 subjects residing in 11 of these counties, county-wide exposure to fine particles was estimated from outdoor ambient concentrations measured during 1979-1983 and RRs were calculated as a function of these PM(2.5) levels (mean of 23.4 microg/m(3)). For the initial period, 1973-1982, a small positive risk was found: RR was 1.04 (1.01-1.07) for a 10-microg/m(3) increase in PM(2.5). For the subsequent period, 1983-2002, this risk was no longer present: RR was 1.00 (0.98-1.02). For the entire follow-up period, RR was 1.01 (0.99-1.03). The RRs varied somewhat among major subgroups defined by sex, age, education level, smoking status, and health status. None of the subgroups that had significantly elevated RRs during 1973-1982 had significantly elevated RRs during 1983-2002. The RRs showed no substantial variation by county of residence during any of the three follow-up periods. Subjects in the two counties with the highest PM(2.5) levels (mean of 36.1 microg/m(3)) had no greater risk of death than those in the two counties with the lowest PM(2.5) levels (mean of 13.1 microg/m(3)). These epidemiologic results do not support a current relationship between fine particulate pollution and total mortality in elderly Californians, but they do not rule out a small effect, particularly before 1983.
在一些队列研究中，细颗粒物空气污染与长期死亡率升高有关，这种关联对制定细颗粒物（PM2.5）空气质量法规产生了影响。然而，由于方法学问题、相互矛盾的研究结果以及缺乏公认的因果机制，这一流行病学证据受到了质疑。为了进一步评估这种关联，我们在一组49975名加利福尼亚州老年人中研究了细颗粒物空气污染与总死亡率之间的长期关系，这些老年人在1973年时的平均年龄为65岁。这些受试者居住在加利福尼亚州的25个县，于1959年入组，1972年再次联系，并从1973年至2002年进行随访；共确定了39846例死亡病例。使用比例风险回归模型，根据居住县确定他们在1973 - 2002年期间的死亡相对风险（RR）和95%置信区间（CI）。模型对年龄、性别、吸烟、种族、教育程度、婚姻状况、体重指数、职业暴露、运动和饮食因素进行了调整。对于居住在其中11个县的35789名受试者，根据1979 - 1983年期间测量的室外环境浓度估算了全县范围内的细颗粒物暴露，并根据这些PM2.5水平（平均为23.4微克/立方米）计算RR。在初始阶段，即1973 - 1982年，发现了一个小的正风险：PM2.5每增加10微克/立方米，RR为1.04（1.01 - 1.07）。在随后的阶段，即1983 - 2002年，这种风险不再存在：RR为1.00（0.98 - 1.02）。在整个随访期间，RR为1.01（0.99 - 1.03）。RR在按性别、年龄、教育水平、吸烟状况和健康状况定义的主要亚组中略有不同。在1973 - 1982年期间RR显著升高的亚组中，没有一个在1983 - 2002年期间RR显著升高。在三个随访期的任何一个期间，RR在居住县之间均无实质性差异。PM2.5水平最高的两个县（平均为36.1微克/立方米）的受试者的死亡风险并不高于PM2.5水平最低的两个县（平均为13.1微克/立方米）的受试者。这些流行病学结果不支持目前加利福尼亚州老年人中细颗粒物污染与总死亡率之间的关系，但也不排除存在小的影响，特别是在1983年之前。
