McKenzie Lisa M, Allshouse William B, Byers Tim E, Bedrick Edward J, Serdar Berrin, Adgate John L
Department of Environmental and Occupational Health, Colorado School of Public Health, University of Colorado Anschutz Campus, Aurora, Colorado, United States of America.
Department of Epidemiology, Colorado School of Public Health, University of Colorado Anschutz Campus, Aurora, Colorado, United States of America.
PLoS One. 2017 Feb 15;12(2):e0170423. doi: 10.1371/journal.pone.0170423. eCollection 2017.
Oil and gas development emits known hematological carcinogens, such as benzene, and increasingly occurs in residential areas. We explored whether residential proximity to oil and gas development was associated with risk for hematologic cancers using a registry-based case-control study design.
Participants were 0-24 years old, living in rural Colorado, and diagnosed with cancer between 2001-2013. For each child in our study, we calculated inverse distance weighted (IDW) oil and gas well counts within a 16.1-kilometer radius of residence at cancer diagnosis for each year in a 10 year latency period to estimate density of oil and gas development. Logistic regression, adjusted for age, race, gender, income, and elevation was used to estimate associations across IDW well count tertiles for 87 acute lymphocytic leukemia (ALL) cases and 50 non-Hodgkin lymphoma (NHL) cases, compared to 528 controls with non-hematologic cancers.
Overall, ALL cases 0-24 years old were more likely to live in the highest IDW well count tertiles compared to controls, but findings differed substantially by age. For ages 5-24, ALL cases were 4.3 times as likely to live in the highest tertile, compared to controls (95% CI: 1.1 to 16), with a monotonic increase in risk across tertiles (trend p-value = 0.035). Further adjustment for year of diagnosis increased the association. No association was found between ALL for children aged 0-4 years or NHL and IDW well counts. While our study benefited from the ability to select cases and controls from the same population, use of cancer-controls, the limited number of ALL and NHL cases, and aggregation of ages into five year ranges, may have biased our associations toward the null. In addition, absence of information on O&G well activities, meteorology, and topography likely reduced temporal and spatial specificity in IDW well counts.
Because oil and gas development has potential to expose a large population to known hematologic carcinogens, further study is clearly needed to substantiate both our positive and negative findings. Future studies should incorporate information on oil and gas development activities and production levels, as well as levels of specific pollutants of interest (e.g. benzene) near homes, schools, and day care centers; provide age-specific residential histories; compare cases to controls without cancer; and address other potential confounders, and environmental stressors.
石油和天然气开发会释放已知的血液系统致癌物，如苯，且此类开发在居民区越来越常见。我们采用基于登记处的病例对照研究设计，探讨居住在靠近石油和天然气开发区域是否与血液系统癌症风险相关。
研究对象为0至24岁、居住在科罗拉多州农村且在2001年至2013年期间被诊断患有癌症的人群。对于我们研究中的每个儿童，我们计算了在癌症诊断时10年潜伏期内每年居住半径16.1公里范围内的反距离加权（IDW）油气井数量，以估计油气开发密度。使用对年龄、种族、性别、收入和海拔进行调整的逻辑回归，来估计87例急性淋巴细胞白血病（ALL）病例和50例非霍奇金淋巴瘤（NHL）病例与528例非血液系统癌症对照相比，IDW井数三分位数之间的关联。
总体而言，与对照组相比，0至24岁的ALL病例更有可能居住在IDW井数最高的三分位数区域，但结果在不同年龄组中差异很大。对于5至24岁的人群，ALL病例居住在最高三分位数区域的可能性是对照组的4.3倍（95%置信区间：1.1至16），三分位数之间风险呈单调增加（趋势p值 = 0.035）。对诊断年份进行进一步调整后，关联增强。未发现0至4岁儿童的ALL或NHL与IDW井数之间存在关联。虽然我们的研究受益于能够从同一人群中选择病例和对照、使用癌症对照，但ALL和NHL病例数量有限以及将年龄聚合为五年范围，可能使我们的关联偏向于零。此外，缺乏关于油气井活动、气象和地形的信息可能降低了IDW井数的时间和空间特异性。
由于石油和天然气开发有可能使大量人群暴露于已知的血液系统致癌物中，显然需要进一步研究来证实我们的阳性和阴性发现。未来的研究应纳入有关油气开发活动和生产水平的信息，以及家庭、学校和日托中心附近感兴趣的特定污染物（如苯）的水平；提供特定年龄的居住史；将病例与无癌症对照进行比较；并解决其他潜在的混杂因素和环境应激源。
