Particulate Matter Air Pollution Exposure,Distance to Road,and Incident Lung Cancer in the Nurses’ Health Study Cohort

Background: A body of literature has suggested an elevated risk of lung cancer associated with particulate matter and traffic-related pollutants.Objective: We examined the relation of lung cancer incidence with long-term residential exposures to ambient particulate matter and residential distance to roadway, as a proxy for traffic-related exposures.Methods: For participants in the Nurses’ Health Study, a nationwide prospective cohort of women, we estimated 72-month average exposures to PM_2.5, PM_2.5–10, and PM₁₀ and residential distance to road. Follow-up for incident cases of lung cancer occurred from 1994 through 2010. Cox proportional hazards models were adjusted for potential confounders. Effect modification by smoking status was examined.Results: During 1,510,027 person-years, 2,155 incident cases of lung cancer were observed among 103,650 participants. In fully adjusted models, a 10-μg/m³ increase in 72-month average PM₁₀ [hazard ratio (HR) = 1.04; 95% CI: 0.95, 1.14], PM_2.5 (HR = 1.06; 95% CI: 0.91, 1.25), or PM_2.5–10 (HR = 1.05; 95% CI: 0.92, 1.20) was positively associated with lung cancer. When the cohort was restricted to never-smokers and to former smokers who had quit at least 10 years before, the associations appeared to increase and were strongest for PM_2.5 (PM₁₀: HR = 1.15; 95% CI: 1.00, 1.32; PM_2.5: HR = 1.37; 95% CI: 1.06, 1.77; PM_2.5–10: HR = 1.11; 95% CI: 0.90, 1.37). Results were most elevated when restricted to the most prevalent subtype, adenocarcinomas. Risks with roadway proximity were less consistent.Conclusions: Our findings support those from other studies indicating increased risk of incident lung cancer associated with ambient PM exposures, especially among never- and long-term former smokers.Citation: Puett RC, Hart JE, Yanosky JD, Spiegelman D, Wang M, Fisher JA, Hong B, Laden F. 2014. Particulate matter air pollution exposure, distance to road, and incident lung cancer in the Nurses’ Health Study Cohort. Environ Health Perspect 122:926–932; http://dx.doi.org/10.1289/ehp.1307490     

A Prospective Analysis of Airborne Metal Exposures and Risk of Parkinson Disease in the Nurses’ Health Study Cohort

Background: Exposure to metals has been implicated in the pathogenesis of Parkinson disease (PD).Objectives: We sought to examine in a large prospective study of female nurses whether exposure to airborne metals was associated with risk of PD.Methods: We linked the U.S. Environmental Protection Agency (EPA)’s Air Toxics tract-level data with the Nurses’ Health Study, a prospective cohort of female nurses. Over the course of 18 years of follow-up from 1990 through 2008, we identified 425 incident cases of PD. We examined the association of risk of PD with the following metals that were part of the first U.S. EPA collections in 1990, 1996, and 1999: arsenic, antimony, cadmium, chromium, lead, manganese, mercury, and nickel. To estimate hazard ratios (HRs) and 95% CIs, we used the Cox proportional hazards model, adjusting for age, smoking, and population density.Results: In adjusted models, the HR for the highest compared with the lowest quartile of each metal ranged from 0.78 (95% CI: 0.59, 1.04) for chromium to 1.33 (95% CI: 0.98, 1.79) for mercury.Conclusions: Overall, we found limited evidence for the association between adulthood ambient exposure to metals and risk of PD. The results for mercury need to be confirmed in future studies.Citation: Palacios N, Fitzgerald K, Roberts AL, Hart JE, Weisskopf MG, Schwarzschild MA, Ascherio A, Laden F. 2014. A prospective analysis of airborne metal exposures and risk of Parkinson disease in the Nurses’ Health Study Cohort. Environ Health Perspect 122:933–938; http://dx.doi.org/10.1289/ehp.1307218     

Cumulative Lead Exposure and Age at Menopause in the Nurses’ Health Study Cohort

Background: Early menopause has been associated with many adverse health outcomes, including increased risk of cardiovascular disease morbidity and mortality. Lead has been found to be adversely associated with female reproductive function, but whether exposures experienced by the general population are associated with altered age at menopause has not been explored.Objective: Our goal was to assess the association between cumulative lead exposure and age at natural menopause.Methods: Self-reported menopausal status and bone lead concentration measured with K-shell X-ray fluorescence—a biomarker of cumulative lead exposure—were obtained from 434 women participants in the Nurses’ Health Study.Results: The mean (± SD) age at natural menopause was 50.8 ± 3.6 years. Higher tibia lead level was associated with younger age at menopause. In adjusted analyses, the average age of menopause for women in the highest tertile of tibia lead was 1.21 years younger (95% CI: –2.08, –0.35) than for women in the lowest tertile (p-trend = 0.006). Although the number of cases was small (n = 23), the odds ratio for early menopause (< 45 years of age) was 5.30 (95% CI: 1.42, 19.78) for women in the highest tertile of tibia lead compared with those in the lowest tertile (p-trend = 0.006). There was no association between patella or blood lead and age at menopause.Conclusions: Our results support an association between low-level cumulative lead exposure and an earlier age at menopause. These data suggest that low-level lead exposure may contribute to menopause-related health outcomes in older women through effects on age at menopause.Citation: Eum KD, Weisskopf MG, Nie LH, Hu H, Korrick SA. 2014. Cumulative lead exposure and age at menopause in the Nurses’ Health Study Cohort. Environ Health Perspect 122:229–234; http://dx.doi.org/10.1289/ehp.1206399     

Chronic Fine and Coarse Particulate Exposure,Mortality, and Coronary Heart Disease in the Nurses’ Health Study

Background

The relationship of fine particulate matter < 2.5 μm in diameter (PM_2.5) air pollution with mortality and cardiovascular disease is well established, with more recent long-term studies reporting larger effect sizes than earlier long-term studies. Some studies have suggested the coarse fraction, particles between 2.5 and 10 μm (PM_10–2.5), may also be important. With respect to mortality and cardiovascular events, questions remain regarding the relative strength of effect sizes for chronic exposure to fine and coarse particles.

Objectives

We examined the relationship of chronic PM_2.5 and PM_10–2.5 exposures with all-cause mortality and fatal and nonfatal incident coronary heart disease (CHD), adjusting for time-varying covariates.

Methods

The current study included women from the Nurses’ Health Study living in metropolitan areas of the northeastern and midwestern United States. Follow-up was from 1992 to 2002. We used geographic information systems–based spatial smoothing models to estimate monthly exposures at each participant’s residence.

Results

We found increased risk of all-cause mortality [hazard ratio (HR), 1.26; 95% confidence interval (CI), 1.02–1.54] and fatal CHD (HR = 2.02; 95% CI, 1.07–3.78) associated with each 10-μg/m³ increase in annual PM_2.5 exposure. The association between fatal CHD and PM_10–2.5 was weaker.

Conclusions

Our findings contribute to growing evidence that chronic PM_2.5 exposure is associated with risk of all-cause and cardiovascular mortality.     

Air Pollution Exposures During Adulthood and Risk of Endometriosis in the Nurses’ Health Study II

Background: Particulate matter and proximity to large roadways may promote disease mechanisms, including systemic inflammation, hormonal alteration, and vascular proliferation, that may contribute to the development and severity of endometriosis.Objective: Our goal was to determine the association of air pollution exposures during adulthood, including distance to road, particulate matter < 2.5 μm, between 2.5 and 10 μm, and < 10 μm, (PM_2.5, PM_10–2.5, PM₁₀), and timing of exposure with risk of endometriosis in the Nurses’ Health Study II.Methods: Proximity to major roadways and outdoor levels of PM_2.5, PM_10–2.5, and PM₁₀ were determined for all residential addresses from 1993 to 2007. Multivariable-adjusted time-varying Cox proportional hazard models were used to estimate the relation between these air pollution exposures and endometriosis risk.Results: Among 84,060 women, 2,486 incident cases of surgically confirmed endometriosis were identified over 710,230 person-years of follow-up. There was no evidence of an association between endometriosis risk and distance to road or exposure to PM_2.5, PM_10–2.5, or PM₁₀ averaged over follow-up or during the previous 2- or 4-year period.Conclusions: Traffic and air pollution exposures during adulthood were not associated with incident endometriosis in this cohort of women.Citation: Mahalingaiah S, Hart JE, Laden F, Aschengrau A, Missmer SA. 2014. Air pollution exposures during adulthood and risk of endometriosis in the Nurses’ Health Study II. Environ Health Perspect 122:58–64; http://dx.doi.org/10.1289/ehp.1306627     

Reproductive Factors and Risk of Thyroid Cancer in Women: An Analysis in the Nurses’ Health Study II

BackgroundThe incidence of thyroid cancer in women is increasing at an alarming rate, with greatest risk in the reproductive years. Establishing relationships of hormonally related reproductive factors with thyroid cancer has been difficult. We aimed to elucidate potential risk factors for thyroid cancer in a large cohort of women.MethodsAmong 116,228 women in the Nurses’ Health Study II followed from 1989 to 2013, 620 cases of thyroid cancer were identified. We examined reproductive and hormone-related factors, including age at menarche, age at menopause, parity, oral contraceptive use, and postmenopausal hormone therapy use. Pregnancy, reproductive years, and months of breastfeeding were used as surrogate markers for exposure to endogenous reproductive hormones. We used multivariable Cox models to calculate relative risks and 95% confidence intervals for the associations between these factors and risk of thyroid cancer.ResultsNumber of reproductive years of 41 years or more was associated with more than double the risk of thyroid cancer compared with 30 years or fewer (relative risk, 2.20; 95% confidence interval, 1.19–4.06). The other variables analyzed (parity number, months of breastfeeding, age at menarche, menopausal status, and postmenopausal hormone therapy) were not associated with the risk of thyroid cancer. Women who entered menopause at age 45 years or older had a higher risk of thyroid cancer compared with women who entered menopause at a younger age. This result did not reach statistical significance; however, there was a linear trend between later age at menopause and increased risk of thyroid cancer (p_trend = .009).ConclusionsThis study used a unique large, longitudinal dataset to assess thyroid cancer risk factors and potential confounders over an extended time frame. Our key finding suggests increased risk of thyroid cancer may be associated with a variety of indicators of longer reproductive years. The Nurses’ Health Study II has provided new insights into the hormonal risks associated with thyroid cancer.     

Autism Spectrum Disorder and Particulate Matter Air Pollution before,during, and after Pregnancy: A Nested Case–Control Analysis within the Nurses’ Health Study II Cohort

Background

Autism spectrum disorder (ASD) is a developmental disorder with increasing prevalence worldwide, yet has unclear etiology.

Objective

We explored the association between maternal exposure to particulate matter (PM) air pollution and odds of ASD in her child.

Methods

We conducted a nested case–control study of participants in the Nurses’ Health Study II (NHS II), a prospective cohort of 116,430 U.S. female nurses recruited in 1989, followed by biennial mailed questionnaires. Subjects were NHS II participants’ children born 1990–2002 with ASD (n = 245), and children without ASD (n = 1,522) randomly selected using frequency matching for birth years. Diagnosis of ASD was based on maternal report, which was validated against the Autism Diagnostic Interview-Revised in a subset. Monthly averages of PM with diameters ≤ 2.5 μm (PM_2.5) and 2.5–10 μm (PM_10–2.5) were predicted from a spatiotemporal model for the continental United States and linked to residential addresses.

Results

PM_2.5 exposure during pregnancy was associated with increased odds of ASD, with an adjusted odds ratio (OR) for ASD per interquartile range (IQR) higher PM_2.5 (4.42 μg/m³) of 1.57 (95% CI: 1.22, 2.03) among women with the same address before and after pregnancy (160 cases, 986 controls). Associations with PM_2.5 exposure 9 months before or after the pregnancy were weaker in independent models and null when all three time periods were included, whereas the association with the 9 months of pregnancy remained (OR = 1.63; 95% CI: 1.08, 2.47). The association between ASD and PM_2.5 was stronger for exposure during the third trimester (OR = 1.42 per IQR increase in PM_2.5; 95% CI: 1.09, 1.86) than during the first two trimesters (ORs = 1.06 and 1.00) when mutually adjusted. There was little association between PM_10–2.5 and ASD.

Conclusions

Higher maternal exposure to PM_2.5 during pregnancy, particularly the third trimester, was associated with greater odds of a child having ASD.

Citation

Raz R, Roberts AL, Lyall K, Hart JE, Just AC, Laden F, Weisskopf MG. 2015. Autism spectrum disorder and particulate matter air pollution before, during, and after pregnancy: a nested case–control analysis within the Nurses’ Health Study II cohort. Environ Health Perspect 123:264–270; http://dx.doi.org/10.1289/ehp.1408133     

Impact of smoking and smoking cessation on health-related quality of life in women in the Nurses’ Health Study

Purpose

To examine the relationship between smoking and health-related quality of life (HRQOL) and the impact of quitting smoking on changes in HRQOL among women in the two Nurses’ Health Study (NHS) cohorts (n = 158,736) who were 29 to 71 years of age in 1992/1993 when they reported data on smoking status and completed the Short Form-36^® version 1 (SF-36^®).

Methods

At baseline, the SF-36^® physical component scores (SF-PCS) and mental component scores (SF-MCS) were examined by smoking status (never, 56%, former, 32%, and current, 13%) within 10-year age groups. Smoking characteristics were analyzed as correlates of SF-36^®. Changes in smoking status and SF-PCS and SF-MCS, adjusted for comorbid disease and other covariates, were reassessed at 4-year intervals among current smokers in 1992/1993 and those who either continued smoking after 4 and 8 years or reported not smoking at both intervals.

Results

Smokers had lower HRQOL (SF-PCS and SF-MCS) as compared to never and former smokers. Current smoking, cigarettes per day and time since quitting were associated with significantly lower SF-PCS and SF-MCS. Continuing smokers and those who quit had significant declines in SF-PCS over time and significant improvements in SF-MCS at 8 years. There was minimal difference between groups, with some greater improvements in SF-MCS among those reporting non-smoking at 8 years. These findings support the lower ratings of HRQOL by smokers, but quitting alone, after an average of 21 years of smoking, did not improve HRQOL. Further study focused on the HRQOL impact of quitting smoking is needed.     

Electric Blanket Use and Risk of Thyroid Cancer in the Women’s Health Initiative Observational Cohort

Thyroid cancer disproportionally affects more women than men. The aim of this study was to assess whether exposure to extremely low frequency electric magnetic fields from electric blankets (EBs) was associated with the development of thyroid cancer. Data were analyzed from 89,527 women who participated in the Women’s Health Initiative Observational Study and who responded to questions concerning prior use of EBs. During a mean follow-up of 12.2 years, 190 incident cases of thyroid cancer were identified. We estimated the hazard ratio (HR) and 95 percent confidence interval (CI) of incident thyroid cancer associated with EB use by Cox’s proportional hazard model, adjusted for selected covariates. A majority, 57 percent, of the women in the cohort reported the use of EBs while sleeping and/or for warming the bed before sleep. No association was found between use of EBs and subsequent risk of thyroid cancer (HR = 0.98, 95 percent CI 0.72–1.32). Duration of EB use measured in years, months, or hours had no effect on risk. These results did not change when the cases were limited to papillary thyroid cancer, the most frequently occurring histologic type. The results of this study do not support possible health hazards of EBs in regards to thyroid cancer risk.     

Association of Urinary Concentrations of Bisphenol A and Phthalate Metabolites with Risk of Type 2 Diabetes: A Prospective Investigation in the Nurses’ Health Study (NHS) and NHSII Cohorts

Background: Prospective evidence regarding associations for exposures to bisphenol A (BPA) and phthalates with type 2 diabetes (T2D) is lacking.Objective: We prospectively examined urinary concentrations of BPA and phthalate metabolites with T2D risk.Methods: We measured BPA and eight major phthalate metabolites among 971 incident T2D case–control pairs from the Nurses’ Health Study (NHS) (mean age, 65.6 years) and NHSII (mean age, 45.6 years).Results: In the NHSII, BPA levels were not associated with incident T2D in multivariate-adjusted analysis until body mass index was adjusted: odds ratio (OR) comparing extreme BPA quartiles increased from 1.40 (95% CI: 0.91, 2.15) to 2.08 (95% CI: 1.17, 3.69; p_trend = 0.02) with such an adjustment. In contrast, BPA concentrations were not associated with T2D in the NHS (OR = 0.81; 95% CI: 0.48, 1.38; p_trend = 0.45). Likewise, urinary concentrations of total phthalate metabolites were associated with T2D in the NHSII (OR comparing extreme quartiles = 2.14; 95% CI: 1.19, 3.85; p_trend = 0.02), but not in the NHS (OR = 0.87; 95% CI: 0.49, 1.53; p_trend = 0.29). Summed metabolites of butyl phthalates or di-(2-ethylhexyl) phthalates were significantly associated with T2D only in the NHSII; ORs comparing extreme quartiles were 3.16 (95% CI: 1.68, 5.95; p_trend = 0.0002) and 1.91 (95% CI: 1.04, 3.49; p_trend = 0.20), respectively.Conclusions: These results suggest that BPA and phthalate exposures may be associated with the risk of T2D among middle-aged, but not older, women. The divergent findings between the two cohorts might be explained by menopausal status or simply by chance. Clearly, these results need to be interpreted with caution and should be replicated in future studies, ideally with multiple urine samples collected prospectively to improve the measurement of these exposures with short half-lives.Citation: Sun Q, Cornelis MC, Townsend MK, Tobias DK, Eliassen AH, Franke AA, Hauser R, Hu FB. 2014. Association of urinary concentrations of bisphenol A and phthalate metabolites with risk of type 2 diabetes: a prospective investigation in the Nurses’ Health Study (NHS) and NHSII Cohorts. Environ Health Perspect 122:616–623; http://dx.doi.org/10.1289/ehp.1307201     

Sources of Fine Particulate Matter and Risk of Preterm Birth in Connecticut, 2000–2006: A Longitudinal Study

Background: Previous studies have examined fine particulate matter (≤ 2.5 μm; PM_2.5) and preterm birth, but there is a dearth of longitudinal studies on this topic and a paucity of studies that have investigated specific sources of this exposure.Objectives: Our aim was to assess whether anthropogenic sources are associated with risk of preterm birth, comparing successive pregnancies to the same woman.Methods: Birth certificates were used to select women who had vaginal singleton live births at least twice in Connecticut during 2000–2006 (n = 23,123 women, n = 48,208 births). We procured 4,085 daily samples of PM_2.5 on Teflon filters from the Connecticut Department of Environmental Protection for six cities in Connecticut. Filters were analyzed for chemical composition, and Positive Matrix Factorization was used to determine contributions of PM_2.5 sources. Risk estimates were calculated with conditional logistic regression, matching pregnancies to the same women.Results: Odds ratios of preterm birth per interquartile range increase in whole pregnancy exposure to dust, motor vehicle emissions, oil combustion, and regional sulfur PM_2.5 sources were 1.01 (95% CI: 0.93, 1.09), 1.01 (95% CI: 0.92, 1.10), 1.00 (95% CI: 0.89, 1.12), and 1.09 (95% CI: 0.97, 1.22), respectively.Conclusion: This was the first study of PM_2.5 sources and preterm birth, and the first matched analysis, that better addresses individual-level confounding potentially inherent in all past studies. There was insufficient evidence to suggest that sources were statistically significantly associated with preterm birth. However, elevated central estimates and previously observed associations with mass concentration motivate the need for further research. Future studies would benefit from high source exposure settings and longitudinal study designs, such as that adopted in this study.Citation: Pereira G, Bell ML, Lee HJ, Koutrakis P, Belanger K. 2014. Sources of fine particulate matter and risk of preterm birth in Connecticut, 2000–2006: a longitudinal study. Environ Health Perspect 122:1117–1122; http://dx.doi.org/10.1289/ehp.1307741     

Perinatal Air Pollutant Exposures and Autism Spectrum Disorder in the Children of Nurses’ Health Study II Participants

Objective: Air pollution contains many toxicants known to affect neurological function and to have effects on the fetus in utero. Recent studies have reported associations between perinatal exposure to air pollutants and autism spectrum disorder (ASD) in children. We tested the hypothesis that perinatal exposure to air pollutants is associated with ASD, focusing on pollutants associated with ASD in prior studies.Methods: We estimated associations between U.S. Environmental Protection Agency–modeled levels of hazardous air pollutants at the time and place of birth and ASD in the children of participants in the Nurses’ Health Study II (325 cases, 22,101 controls). Our analyses focused on pollutants associated with ASD in prior research. We accounted for possible confounding and ascertainment bias by adjusting for family-level socioeconomic status (maternal grandparents’ education) and census tract–level socioeconomic measures (e.g., tract median income and percent college educated), as well as maternal age at birth and year of birth. We also examined possible differences in the relationship between ASD and pollutant exposures by child’s sex.Results: Perinatal exposures to the highest versus lowest quintile of diesel, lead, manganese, mercury, methylene chloride, and an overall measure of metals were significantly associated with ASD, with odds ratios ranging from 1.5 (for overall metals measure) to 2.0 (for diesel and mercury). In addition, linear trends were positive and statistically significant for these exposures (p < .05 for each). For most pollutants, associations were stronger for boys (279 cases) than for girls (46 cases) and significantly different according to sex.Conclusions: Perinatal exposure to air pollutants may increase risk for ASD. Additionally, future studies should consider sex-specific biological pathways connecting perinatal exposure to pollutants with ASD.     

Dietary Cadmium Exposure and Risk of Breast,Endometrial, and Ovarian Cancer in the Women’s Health Initiative

Background: In vitro and animal data suggest that cadmium, a heavy metal that contaminates some foods and tobacco plants, is an estrogenic endocrine disruptor. Elevated estrogen exposure is associated with breast, endometrial, and ovarian cancer risk.Objectives: We examined the association between dietary cadmium intake and risk of these cancers in the large, well-characterized Women’s Health Initiative (WHI).Methods: A total of 155,069 postmenopausal women, 50–79 years of age, who were enrolled in the WHI clinical trials or observational study, participated in this study. We estimated dietary cadmium consumption by combining baseline food frequency questionnaire responses with U.S. Food and Drug Administration data on food cadmium content. Participants reported incident invasive breast, endometrial, or ovarian cancer, and WHI centrally adjudicated all cases through August 2009. We applied Cox regression to estimate adjusted hazard ratios (HRs) and 95% CIs for each cancer, comparing quintiles of energy-adjusted dietary cadmium intake.Results: Over an average of 10.5 years, 6,658 invasive breast cancers, 1,198 endometrial cancers, and 735 ovarian cancers were reported. We observed no statistically significant associations between dietary cadmium and risk of any of these cancers after adjustment for potential confounders including total dietary energy intake. Results did not differ in any subgroup of women examined.Conclusions: We found little evidence that dietary cadmium is a risk factor for breast, endometrial, or ovarian cancers in postmenopausal women. Misclassification in dietary cadmium assessment may have attenuated observed associations.Citation: Adams SV, Quraishi SM, Shafer MM, Passarelli MN, Freney EP, Chlebowski RT, Luo J, Meliker JR, Mu L, Neuhouser ML, Newcomb PA. 2014. Dietary cadmium exposure and risk of breast, endometrial, and ovarian cancer in the Women’s Health Initiative. Environ Health Perspect 122:594–600; http://dx.doi.org/10.1289/ehp.1307054     

Prenatal Exposure to Airborne Polycyclic Aromatic Hydrocarbons and Children’s Intelligence at 5 Years of Age in a Prospective Cohort Study in Poland

Background

In this prospective cohort study of Caucasian mothers and children in Krakow, Poland, we evaluated the role of prenatal exposure to urban air pollutants in the pathogenesis of neurobehavioral disorders.

Objectives

The objective of this study was to investigate the relationship between prenatal polycyclic aromatic hydrocarbon (PAH) exposure and child intelligence at 5 years of age, controlling for potential confounders suspected to play a role in neurodevelopment.

Methods

A cohort of pregnant, healthy, nonsmoking women was enrolled in Krakow, Poland, between 2001 and 2006. During pregnancy, participants were invited to complete a questionnaire and undergo 48-hr personal air monitoring to estimate their babies’ exposure, and to provide a blood sample and/or a cord blood sample at the time of delivery. Two hundred fourteen children were followed through 5 years of age, when their nonverbal reasoning ability was assessed using the Raven Coloured Progressive Matrices (RCPM).

Results

We found that higher (above the median of 17.96 ng/m³) prenatal exposure to airborne PAHs (range, 1.8–272.2 ng/m³) was associated with decreased RCPM scores at 5 years of age, after adjusting for potential confounding variables (n = 214). Further adjusting for maternal intelligence, lead, or dietary PAHs did not alter this association. The reduction in RCPM score associated with high airborne PAH exposure corresponded to an estimated average decrease of 3.8 IQ points.

Conclusions

These results suggest that prenatal exposure to airborne PAHs adversely affects children’s cognitive development by 5 years of age, with potential implications for school performance. They are consistent with a recent finding in a parallel cohort in New York City.     

Commonality of Risk Factors for Mothers’ Poor Oral Health and General Health: Baseline Analysis of a Population-Based Birth Cohort Study

Maternal and Child Health Journal - Objective The association between and commonality of risk factors for poor self-rated oral health (SROH) and general health (SRGH) among new mothers has not been...     

Occupational Exposure to Benzene and Non-Hodgkin Lymphoma in a Population-Based Cohort: The Shanghai Women’s Health Study

Background

The association between benzene exposure and non-Hodgkin lymphoma (NHL) has been the subject of debate as a result of inconsistent epidemiologic evidence. An International Agency for Research on Cancer (IARC) working group evaluated benzene in 2009 and noted evidence for a positive association between benzene exposure and NHL risk.

Objective

We evaluated the association between occupational benzene exposure and NHL among 73,087 women enrolled in the prospective population-based Shanghai Women’s Health Study.

Methods

Benzene exposure estimates were derived using a previously developed exposure assessment framework that combined ordinal job-exposure matrix intensity ratings with quantitative benzene exposure measurements from an inspection database of Shanghai factories collected between 1954 and 2000. Associations between benzene exposure metrics and NHL (n = 102 cases) were assessed using Cox proportional hazard models, with study follow-up occurring from December 1996 through December 2009.

Results

Women ever exposed to benzene had a significantly higher risk of NHL [hazard ratio (HR) = 1.87, 95% CI: 1.19, 2.96]. Compared with unexposed women, significant trends in NHL risk were observed for increasing years of benzene exposure (p_trend = 0.006) and increasing cumulative exposure levels (p_trend = 0.005), with the highest duration and cumulative exposure tertiles having a significantly higher association with NHL (HR = 2.07, 95% CI: 1.07, 4.01 and HR = 2.16, 95% CI: 1.17, 3.98, respectively).

Conclusions

Our findings, using a population-based prospective cohort of women with diverse occupational histories, provide additional evidence that occupational exposure to benzene is associated with NHL risk.

Citation

Bassig BA, Friesen MC, Vermeulen R, Shu XO, Purdue MP, Stewart PA, Xiang YB, Chow WH, Zheng T, Ji BT, Yang G, Linet MS, Hu W, Zhang H, Zheng W, Gao YT, Rothman N, Lan Q. 2015. Occupational exposure to benzene and non-Hodgkin lymphoma in a population-based cohort: the Shanghai Women’s Health Study. Environ Health Perspect 123:971–977; http://dx.doi.org/10.1289/ehp.1408307