Background

Iron can cause oxidative stress and DNA damage, and heme iron can catalyze endogenous formation of N-nitroso compounds, which are potent carcinogens. Dietary iron promotes esophageal cancer incidence in animal studies and has been identified as a growth factor for Helicobacter pylori, an established risk factor for stomach cancer.

Methods

We conducted a population-based case-control study of adenocarcinoma of the esophagus (n=124) and stomach (n=154) and 449 controls in Nebraska. Heme iron and total iron intake were estimated from a food-frequency questionnaire and databases of heme and total iron. We used logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI) adjusted for known risk factors.

Results

Esophageal cancer was positively associated with higher intakes of heme iron (ORQ4 vs. Q1 =3.04, 95% CI 1.20–7.72; p-trend=0.009) and total iron from meat sources (ORQ4 vs. Q1 =2.67, 95% CI 0.99–7.16; p-trend=0.050). Risk of stomach cancer was elevated among those with higher intakes of heme iron (ORQ4vs.Q1=1.99, 95% CI 1.00–3.95, p-trend=0.17) and total iron from meat (OR=2.26, 95% CI 1.14–4.46; p-trend=0.11). Iron intake from all dietary sources was not significantly associated with risk of either cancer.

Conclusions

Our results suggest that high intakes of heme and iron from meat may be important dietary risk factors for esophageal and stomach cancer and may partly explain associations with red meat.

Background: Home and garden pesticide use has been linked to cancer and other health outcomes in numerous epidemiological studies. Exposure has generally been self-reported, so the assessment is potentially limited by recall bias and lack of information on specific chemicals.

Objectives: As part of an integrated assessment of residential pesticide exposure, we identified active ingredients and described patterns of storage and use.

Methods: During a home interview of 500 residentially stable households enrolled in the Northern California Childhood Leukemia Study during 2001–2006, trained interviewers inventoried residential pesticide products and queried participants about their storage and use. U.S. Environmental Protection Agency registration numbers, recorded from pesticide product labels, and pesticide chemical codes were matched to public databases to obtain information on active ingredients and chemical class. Poisson regression was used to identify independent predictors of pesticide storage. Analyses were restricted to 259 participating control households.

Results: Ninety-five percent (246 of 259) of the control households stored at least one pesticide product (median, 4). Indicators of higher sociodemographic status predicted more products in storage. We identified the most common characteristics: storage areas (garage, 40%; kitchen, 20%), pests treated (ants, 33%; weeds, 20%), pesticide types (insecticides, 46%; herbicides, 24%), chemical classes (pyrethroids, 77%; botanicals, 50%), active ingredients (pyrethrins, 43%) and synergists (piperonyl butoxide, 42%). Products could contain multiple active ingredients.

Conclusions: Our data on specific active ingredients and patterns of storage and use will inform future etiologic analyses of residential pesticide exposures from self-reported data, particularly among households with young children.

Ovarian cancer is a leading cause of cancer death among women in the United States and it has the highest mortality rate of all gynecologic cancers. Internationally, there is a five-fold variation in incidence and mortality of ovarian cancer, which suggests a role for environmental factors, including diet. Nitrate and nitrite are found in various food items and they are precursors of N-nitroso compounds, which are known carcinogens in animal models. We evaluated dietary nitrate and nitrite intake and epithelial ovarian cancer in the National Institutes of Health (NIH)-AARP Diet and Health Study, including 151 316 women aged 50–71 years at the time of the baseline questionnaire in 1995–1996. The nitrate and nitrite intake was assessed using a 124-item validated food frequency questionnaire. Through 31 December 2006, 709 incident epithelial ovarian cancer cases with complete dietary information were identified. Using Cox proportional hazards regression to estimate hazard ratios and 95% confidence intervals (CIs), women in the highest intake quintile of dietary nitrate had a 31% increased risk (95% CI: 1.01–1.68) of epithelial ovarian cancer, compared with those in the lowest intake quintile. Although there was no association for total dietary nitrite, those in the highest intake category of animal sources of nitrite had a 34% increased risk (95% CI: 1.05–1.69) of ovarian cancer. There were no clear differences in risk by histologic subtype of ovarian cancer. Our findings suggest that a role of dietary nitrate and nitrite in ovarian cancer risk should be followed in other large cohort studies.

Background Previous studies suggest an association between obesity and oesophageal (OA) and oesophagogastric junction adenocarcinomas (OGJA). However, these studies have been limited in their ability to assess whether the effects of obesity vary by gender or by the presence of gastro-oesophageal reflux (GERD) symptoms.

Methods Individual participant data from 12 epidemiological studies (8 North American, 3 European and 1 Australian) comprising 1997 OA cases, 1900 OGJA cases and 11 159 control subjects were pooled. Logistic regression was used to estimate study-specific odds ratios (ORs) and 95% confidence intervals (CIs) for the association between body mass index (BMI, kg/m2) and the risk of OA and OGJA. Random-effects meta-analysis was used to combine these ORs. We also investigated effect modification and synergistic interaction of BMI with GERD symptoms and gender.

Results The association of OA and OGJA increased directly with increasing BMI (P for trend <0.001). Compared with individuals with a BMI <25, BMI ≥40 was associated with both OA (OR 4.76, 95% CI 2.96–7.66) and OGJA (OR 3.07, 95% CI 1.89–4.99). These associations were similar when stratified by gender and GERD symptoms. There was evidence for synergistic interaction between BMI and GERD symptoms in relation to OA/OGJA risk.

Conclusions These data indicate that BMI is directly associated with OA and OGJA risk in both men and women and in those with and without GERD symptoms. Disentangling the relationship between BMI and GERD will be important for understanding preventive efforts for OA and OGJA.

Background and aims

Alcohol intake is a strong and well-established risk factor for esophageal squamous cell carcinoma (ESCC), but the association with esophageal adenocarcinoma (EA) or adjacent tumors of the esophagogastric junction (EGJA), remains unclear. Therefore, we determined the association of alcohol intake with ESCC, EA, and EGJA in nine case-control studies and two cohort studies of the Barrett’s Esophagus and Esophageal Adenocarcinoma Consortium (BEACON).

Materials and methods

We collected information on alcohol intake, age, sex, education, body mass index, gastroesophageal reflux, and tobacco smoking from each study. Along with 10,854 controls, 1,821 EA, and 1,837 EGJA, seven studies also collected ESCC cases (n=1,016). Study-specific odds ratios (OR) and 95% confidence intervals (CI) were calculated from multivariate-adjusted logistic regression models for alcohol intake in categories compared to non-drinkers. Summary risk estimates were obtained by random effects models.

Results

We observed no increase in risk of EA or EGJA for increasing levels of any of the alcohol intake measures examined. ORs for the highest frequency category (≥7 drinks per day) were 0.97 (95% CI = 0.68-1.36) for EA and 0.77 (95% CI = 0.54-1.10) for EGJA. Suggestive findings linked moderate intake (e.g. 0.5 to <1 drinks per day) to decreased risk of EA (OR = 0.63 95% CI = 0.41-0.99) and EGJA (OR = 0.78; 95% CI = 0.62-0.99). In contrast, alcohol intake was strongly associated with increased risk of ESCC (OR for ≥7 drinks per day= 9.62, 95%CI=4.26-21.71).

Conclusions

In contrast to ESCC, higher alcohol consumption was not associated with increased risk of either EA or EGJA. The apparent inverse association observed with moderate alcohol intake should be evaluated in future prospective studies.

Background

We hypothesized that diabetes may play a role in thyroid cancer risk due to the parallel secular rise in diabetes prevalence and morbidity in the United States, the higher prevalence of thyroid disorders among diabetics compared with the general population, and the potential roles of metabolic syndrome, obesity, and diabetes as precipitating factors in cancer development.

Methods

We assessed the association between self-reported diabetes and the risk of differentiated thyroid cancer in the NIH-AARP Diet and Health Study, a prospective cohort of 200,556 women and 295,992 men, 50–71 years of age, in 1995–1996. Diabetes status and information on potential confounders was ascertained using a self-administered questionnaire. During an average of 10 years of follow-up, 585 thyroid cancer cases were identified. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for thyroid cancer and thyroid cancer subtypes in men and women according to diabetes status.

Results

Nine percent of the total baseline cohort reported a history of diabetes (7% of women, 10% of men). A nonsignificant 25% increase in thyroid cancer risk (HR = 1.25; 95% CI: 0.95–1.64) was associated with diabetes. Among women, the risk was significantly increased (HR = 1.46, 95% CI: 1.01–2.10). The risk was not elevated among men (HR = 1.04, 95% CI: 0.69–1.58). In this cohort, diabetic women with differentiated thyroid cancer were at somewhat higher risk of follicular thyroid cancer (HR = 1.92; 95% CI: 0.86–4.27) than papillary thyroid cancer (HR = 1.25; 95% CI: 0.80–1.97).

Conclusion

This study lends support to the hypothesis that diabetes increases the risk of differentiated thyroid cancer.

Nitrate and nitrite are precursors of N-nitroso compounds, which induce tumors of the pancreas in animals. The authors evaluated the relation of dietary nitrate and nitrite to pancreatic cancer risk in the NIH-AARP Diet and Health Study. Nitrate and nitrite intakes were assessed at baseline using a 124-item food frequency questionnaire. During approximately 10 years of follow-up between 1995 and 2006, 1,728 incident pancreatic cancer cases were identified. There was no association between total nitrate or nitrite intake and pancreatic cancer in men or women. However, men in the highest quintile of summed nitrate/nitrite intake from processed meat had a nonsignificantly elevated risk of pancreatic cancer (hazard ratio = 1.18, 95% confidence interval: 0.95, 1.47; P-trend = 0.11). The authors observed a stronger increase in risk among men for nitrate/nitrite intake from processed meat at ages 12–13 years (highest quintile vs. lowest: hazard ratio = 1.32, 95% confidence interval: 0.99, 1.76; P-trend = 0.11), though the relation did not achieve statistical significance. The authors found no associations between adult or adolescent nitrate or nitrite intake from processed meats and pancreatic cancer among women. These results provide modest evidence that processed meat sources of dietary nitrate and nitrite may be associated with pancreatic cancer among men and provide no support for the hypothesis in women.

Ingested nitrate can be endogenously reduced to nitrite, which may form N-nitroso compounds, known potent carcinogens. However, some studies have reported no or inverse associations between dietary nitrate intake and cancer risk. These associations may be confounded by a protective effect of folate, which plays a vital role in DNA repair. We evaluated the interaction of dietary and water nitrate intake with total folate intake on breast cancer risk in the Iowa Women’s Health Study. Dietary intake was assessed at study baseline. Nitrate intake from public water was assessed using a historical database on Iowa municipal water supplies. After baseline exclusions, 34,388 postmenopausal women and 2,875 incident breast cancers were included. Overall, neither dietary nor water nitrate was associated with breast cancer risk. Among those with folate intake ≥400 μg/d, breast cancer risk was significantly increased in public water users with the highest nitrate quintile (HR=1.40, 95%CI=1.05–1.87) and private well users (HR=1.38, 95%CI=1.05–1.82) compared to public water users with the lowest nitrate quintile; in contrast, there was no association among those with lower folate intake. Our findings do not support a previous report of increased risk of breast cancer among individuals with high dietary nitrate but low folate intake.

During the past several decades, an increasing incidence of thyroid cancer has been observed worldwide. Nitrate inhibits iodide uptake by the thyroid, potentially disrupting thyroid function. An increased risk of thyroid cancer associated with nitrate intake was recently reported in a cohort study of older women in Iowa. We evaluated dietary nitrate and nitrite intake and thyroid cancer risk overall and for subtypes in the National Institutes of Health-American Association of Retired Persons (NIH-AARP) Diet and Health Study, a large prospective cohort of 490,194 men and women, ages 50–71 years in 1995–1996. Dietary intakes were assessed using a 124-item food frequency questionnaire. During an average of 7 years of follow-up we identified 370 incident thyroid cancer cases (170 men, 200 women) with complete dietary information. Among men, increasing nitrate intake was positively associated with thyroid cancer risk (relative risk (RR) for the highest quintile versus lowest quintile RR=2.28, 95% CI: 1.29–4.04l; p-trend <0.001); however, we observed no trend with intake among women (p-trend=0.61). Nitrite intake was not associated with risk of thyroid cancer for either men or women. We evaluated risk for the two main types of thyroid cancer. We found positive associations for nitrate intake and both papillary (RR = 2.10; 95%CI: 1.09–4.05; p-trend=0.05) and follicular thyroid cancer (RR= 3.42; 95%CI: 1.03–11.4; p-trend=0.01) among men. Nitrite intake was associated with increased risk of follicular thyroid cancer (RR= 2.74; 95%CI: 0.86–8.77; p-trend=0.04) among men. Our results support a role of nitrate in thyroid cancer risk and suggest that further studies to investigate these exposures are warranted.

Background

Although impaired lung function in general has been associated with an increased risk of lung cancer, past studies typically have not attempted to investigate separately the obstructive and restrictive components of respiratory impairment. To deal with this question further, data from a large (n = 176 997) cohort of male Swedish construction workers, for whom spirometry measurements before follow‐up were available, were analysed.

Methods

Cancer incidence for 1971–2001 was obtained through linkage with the national cancer registry. Using a modification of the Global Initiative for Chronic Obstructive Lung Disease criteria for chronic obstructive pulmonary disease (COPD), subjects were classified into five categories of lung function: normal, mild COPD, moderate COPD, severe COPD and restrictive lung disease (RLD). Rate ratios (RR) and 95% confidence intervals (CI) for lung cancer across lung function categories were calculated using Poisson regression, adjusted for age and smoking. Other end points (histological types of lung cancer, non‐lung tobacco‐related cancers, other cancers, total mortality) were also investigated.

Results

834 incident cases of lung cancer were identified. Increased rates of lung cancer were observed for both COPD (mild: RR 1.5, 95% CI 1.2 to 1.9; moderate/severe: RR 2.2, 95% CI 1.8 to 2.7) and RLD (RR 2.0, 95% CI 1.6 to 2.5) relative to normal lung function. These associations did not meaningfully change on applying follow‐up lag times of 5, 10 and 15 years after spirometry. When analysed by histological type, associations with both COPD and RLD were stronger for squamous cell carcinoma and small cell carcinoma, and weaker for adenocarcinoma. Both COPD and RLD were associated with increased rates of total mortality.

Conclusions

Obstructive and restrictive impairments in lung function are associated with increased lung cancer risk.

We conducted a population-based case-control study of adenocarcinoma of the stomach and esophagus in Nebraska, U.S.A. Nitrate concentrations in public drinking water supplies were linked to residential water source histories. Among those using private wells at the time of the interview, we measured nitrate levels in water samples from wells. Dietary nitrate and nitrite were estimated from a food-frequency questionnaire. Among those who primarily used public water supplies (79 distal stomach, 84 esophagus, 321 controls), average nitrate levels were not associated with risk (highest versus lowest quartile: stomach OR=1.2, 95% CI [0.5–2.7]; esophagus OR=1.3, 95% CI [0.6–3.1]). We observed the highest ORs for distal stomach cancer among those with higher water nitrate ingestion and higher intake of processed meat compared with low intakes of both; however, the test for positive interaction was not significant (p=0.213). We did not observe this pattern for esophagus cancer. Increasing intake of nitrate and nitrite from animal sources was associated with elevated ORs for stomach cancer and with a significant positive trend in risk of esophagus cancer (P-trend=0.325 and 0.015, respectively). Larger studies with higher exposures to drinking water sources of nitrate are warranted to further evaluate N-nitroso compound precursors as risk factors for these cancers.

Background

There is increasing interest in using chemicals measured in carpet dust as indicators of chemical exposures. However, investigators have rarely sampled dust repeatedly from the same households and therefore little is known about the variability of chemical levels that exist within and between households in dust samples.

Results

We analyzed 9 polycyclic aromatic hydrocarbons, 6 polychlorinated biphenyls, and nicotine in 68 carpet-dust samples from 21 households in agricultural communities of Fresno County, California collected from 2003-2005. Chemical concentrations (ng per g dust) ranged from < 2-3,609 for 9 polycyclic aromatic hydrocarbons, from < 1-150 for 6 polychlorinated biphenyls, and from < 20-7,776 for nicotine. We used random-effects models to estimate variance components for concentrations of each of these carpet-dust chemicals and calculated the variance ratio, λ, defined as the ratio of the within-household variance component to the between-household variance component. Subsequently, we used the variance ratios calculated from our data, to illustrate the potential effect of measurement error on the attenuation of odds ratios in hypothetical case-control studies. We found that the median value of the estimated variance ratios was 0.33 (range: 0.13-0.72). Correspondingly, in case-control studies of associations between these carpet-dust chemicals and disease, given the collection of only one measurement per household and a hypothetical odds ratio of 1.5, we expect that the observed odds ratios would range from 1.27 to 1.43. Moreover, for each of the chemicals analyzed, the collection of three repeated dust samples would limit the expected magnitude of odds ratio attenuation to less than 20%.

Conclusions

Our findings suggest that attenuation bias should be relatively modest when using these semi-volatile carpet-dust chemicals as exposure surrogates in epidemiologic studies.

Background

Red and processed meats could increase cancer risk via several potential mechanisms involving iron, heterocyclic amines, polycyclic aromatic hydrocarbons and N-nitroso compounds. Although there have been multiple studies of meat and colorectal cancer, other gastrointestinal malignancies are understudied.

Methods

We estimated hazards ratios (HR) and 95% confidence intervals (CI) for the association between meat, meat components, and meat cooking by-products and risk of esophageal or gastric cancer in a large cohort study. During approximately 10 years of follow-up, we accrued 215 esophageal squamous cell carcinomas, 630 esophageal adenocarcinomas, 454 gastric cardia adenocarcinomas and 501 gastric non-cardia adenocarcinomas.

Results

Red meat intake was positively associated with esophageal squamous cell carcinoma (HR for the top versus bottom quintile = 1.79, 95% CI: 1.07–3.01, P for trend = 0.019). Individuals in the highest intake quintile of 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (DiMeIQx) had an increased risk for gastric cardia cancer (HR = 1.44, 95% CI: 1.01–2.07, P for trend = 0.104). Furthermore, those in the highest quintile of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) or heme iron intake had a suggestive increased risk for esophageal adenocarcinoma (HR = 1.35, 95% CI: 0.97–1.89, P for trend = 0.022; HR = 1.45, 95% CI: 0.99–2.12, P for trend = 0.463; HR = 1.47, 95% CI: 0.99-2.20, P for trend = 0.063, respectively). Benzo[a]pyrene, nitrate and nitrite were not associated with esophageal or gastric cancer.

Conclusions

We found positive associations between red meat intake and esophageal squamous cell carcinoma, and between DiMeIQx intake and gastric cardia cancer.

Background

The increasing incidence of thyroid cancer in the United States is well documented. In this study, we assessed the incidence patterns by histologic type according to demographic and tumor characteristics to further our understanding of these cancers.

Methods

We used the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program for cases diagnosed during 1992–2006 to investigate patterns for the four major histologic types of thyroid cancer by gender, race/ethnicity, and age as well as registry, tumor stage, and size.

Results

Among women, papillary thyroid cancer rates were highest among Asians (10.96 per 100,000 woman-years) and lowest among blacks (4.90 per 100,000 woman-years); follicular cancer rates did not vary substantially by race/ethnicity (p-values >0.05), medullary cancer rates were highest among Hispanics (0.21 per 100,000 woman-years) and whites (0.22 per 100,000 woman-years), and anaplastic rates were highest among Hispanics (0.17 per 100,000 woman-years). Among men, both papillary and follicular thyroid cancer rates were highest among whites (3.58 and 0.58 per 100,000 man-years, respectively), medullary cancer rates were highest among Hispanics (0.18 per 100,000 man-years), and anaplastic rates were highest among Asians (0.11 per 100,000 man-years). Racial/ethnic-specific rates did not vary notably across registries. In contrast to age-specific rates of papillary thyroid cancer that peaked in midlife (age 50), especially pronounced among women, rates for follicular, medullary, and anaplastic types continued to rise across virtually the entire age range, especially for anaplastic carcinomas. Female-to-male incidence rate ratios among whites decreased with age most steeply for the follicular type and least steeply for the medullary type; it was <1 until the very oldest ages for the anaplastic type.

Conclusion

We conclude that the similar age-specific patterns and lack of geographical variation across the SEER racial/ethnic groups indicate that detection effects cannot completely explain the observed thyroid cancer incidence patterns as variation in the amount or quality of healthcare provided has been shown to vary by SEER racial/ethnic groups, gender, and age. We find that the variations in age-specific patterns by gender and across histologic types are intriguing and recommend that future etiologic investigation focus on exogenous and endogenous exposures that are experienced similarly by racial/ethnic groups, more strongly among women, and distinctively by age.

Background

Meat could be involved in bladder carcinogenesis via multiple potentially carcinogenic meat-related compounds related to cooking and processing, including nitrate, nitrite, heterocyclic amines (HCAs), and polycyclic aromatic hydrocarbons. We comprehensively investigated the association between meat and meat components and bladder cancer.

Methods

During 7 years of follow-up, 854 transitional cell bladder cancer cases were identified among 300,933 men and women who completed a validated food frequency questionnaire in the large prospective NIH-AARP Diet and Health Study. We estimated intake of nitrate and nitrite from processed meat and HCAs and PAHs from cooked meat using quantitative databases of measured values. We calculated total dietary nitrate and nitrite based on literature values.

Results

The hazard ratios (HR) and 95% confidence intervals (CI) for red meat (HR for fifth compared to first quintile=1.22, 95% CI=0.96–1.54, p-trend=0.07) and the HCA 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) (HR=1.19, 95% CI=0.95–1.48, p-trend=0.06) conferred a borderline statistically significant increased risk of bladder cancer. We observed positive associations in the top quintile for total dietary nitrite (HR=1.28, 95% CI=1.02–1.61, p-trend= 0.06) and nitrate plus nitrite intake from processed meat (HR=1.29 95% CI=1.00–1.67, p-trend= 0.11).

Conclusions

These findings provide modest support for a role for total dietary nitrite and nitrate plus nitrite from processed meat in bladder cancer. Our results also suggest a positive association between red meat and PhIP and bladder carcinogenesis.

Background

Previous studies that showed an association between smoking and adenocarcinomas of the esophagus and esophagogastric junction were limited in their ability to assess differences by tumor site, sex, dose–response, and duration of cigarette smoking cessation.

Methods

We used primary data from 10 population-based case–control studies and two cohort studies from the Barrett’s Esophagus and Esophageal Adenocarcinoma Consortium. Analyses were restricted to white non-Hispanic men and women. Patients were classified as having esophageal adenocarcinoma (n = 1540), esophagogastric junctional adenocarcinoma (n = 1450), or a combination of both (all adenocarcinoma; n = 2990). Control subjects (n = 9453) were population based. Associations between pack-years of cigarette smoking and risks of adenocarcinomas were assessed, as well as their potential modification by sex and duration of smoking cessation. Study-specific odds ratios (ORs) estimated using multivariable logistic regression models, adjusted for age, sex, body mass index, education, and gastroesophageal reflux, were pooled using a meta-analytic methodology to generate summary odds ratios. All statistical tests were two-sided.

Results

The summary odds ratios demonstrated strong associations between cigarette smoking and esophageal adenocarcinoma (OR = 1.96, 95% confidence interval [CI] = 1.64 to 2.34), esophagogastric junctional adenocarcinoma (OR = 2.18, 95% CI = 1.84 to 2.58), and all adenocarcinoma (OR = 2.08, 95% CI = 1.83 to 2.37). In addition, there was a strong dose–response association between pack-years of cigarette smoking and each outcome (P < .001). Compared with current smokers, longer smoking cessation was associated with a decreased risk of all adenocarcinoma after adjusting for pack-years (<10 years of smoking cessation: OR = 0.82, 95% CI = 0.60 to 1.13; and ≥10 years of smoking cessation: OR = 0.71, 95% CI = 0.56 to 0.89). Sex-specific summary odds ratios were similar.

Conclusions

Cigarette smoking is associated with increased risks of adenocarcinomas of the esophagus and esophagogastric junction in white men and women; compared with current smoking, smoking cessation was associated with reduced risks.

Background: Ingestion of inorganic arsenic in drinking water is recognized as a cause of bladder cancer when levels are relatively high (≥ 150 µg/L). The epidemiologic evidence is less clear at the low-to-moderate concentrations typically observed in the United States. Accurate retrospective exposure assessment over a long time period is a major challenge in conducting epidemiologic studies of environmental factors and diseases with long latency, such as cancer.

Objective: We estimated arsenic concentrations in the water supplies of 2,611 participants in a population-based case–control study in northern New England.

Methods: Estimates covered the lifetimes of most study participants and were based on a combination of arsenic measurements at the homes of the participants and statistical modeling of arsenic concentrations in the water supply of both past and current homes. We assigned a residential water supply arsenic concentration for 165,138 (95%) of the total 173,361 lifetime exposure years (EYs) and a workplace water supply arsenic level for 85,195 EYs (86% of reported occupational years).

Results: Three methods accounted for 93% of the residential estimates of arsenic concentration: direct measurement of water samples (27%; median, 0.3 µg/L; range, 0.1–11.5), statistical models of water utility measurement data (49%; median, 0.4 µg/L; range, 0.3–3.3), and statistical models of arsenic concentrations in wells using aquifers in New England (17%; median, 1.6 µg/L; range, 0.6–22.4).

Conclusions: We used a different validation procedure for each of the three methods, and found our estimated levels to be comparable with available measured concentrations. This methodology allowed us to calculate potential drinking water exposure over long periods.

Background

N-nitroso compounds (NOCs) are found in processed meat and are formed endogenously from intake of nitrite and nitrate. Endogenous NOC formation is antagonized by nitrosation inhibitors in fruit and vegetables (e.g., vitamin C) and promoted by heme in red meat. It has been hypothesized that a diet resulting in high exposure to NOCs increases adult glioma risk.

Methods

Using proportional hazards models, we tested this hypothesis among 545,770 participants in the prospective NIH-AARP Diet and Health Study, which assessed dietary intake at baseline (1995–96) with a comprehensive food frequency questionnaire (FFQ) and at ages 12–13 years with an abbreviated FFQ.

Results

During follow-up through 2003, 585 participants were diagnosed with glioma. We found no significant trends in glioma risk for consumption of processed or red meat, nitrate, or vitamin C or E. We found significant positive trends for nitrite intake from plant sources (hazard ratio [HR] for quintile 5 vs. 1, 1.59; 95% confidence interval [CI], 1.20–2.10; p-trend = 0.028) and, unexpectedly, for fruit and vegetable intake (HR, 1.42; 95% CI, 1.08–1.86; p-trend = .0081). Examination of interactions between dietary intakes (e.g., nitrite and vitamin C) and a limited analysis of diet at ages 12–13 provided no support for the NOC hypothesis.

Conclusions

Our results cast doubt on the NOC hypothesis in relation to dietary intake and adult glioma risk.

Impact

Further work is needed on early life diet, adult intake of nitrite from plant sources, and adult intake of fruit and vegetables in relation to adult glioma risk.

Background: Residential proximity to agricultural pesticide applications has been used as a surrogate for exposure in epidemiologic studies, although little is known about the relationship with levels of pesticides in homes.

Objective: We identified determinants of concentrations of agricultural pesticides in dust.

Methods: We collected samples of carpet dust and mapped crops within 1,250 m of 89 residences in California. We measured concentrations of seven pesticides used extensively in agriculture (carbaryl, chlorpyrifos, chlorthal-dimethyl, diazinon, iprodione, phosmet, and simazine). We estimated use of agricultural pesticides near residences from a statewide database alone and by linking the database with crop maps. We calculated the density of pesticide use within 500 and 1,250 m of residences for 180, 365, and 730 days before collection of dust and evaluated relationships between agricultural pesticide use estimates and pesticide concentrations in carpet dust.

Results: For five of the seven pesticides evaluated, residences with use of agricultural pesticides within 1,250 m during the previous 365 days had significantly higher concentrations of pesticides than did residences with no nearby use. The highest correlation with concentrations of pesticides was generally for use reported within 1,250 m of the residence and 730 days before sample collection. Regression models that also accounted for occupational and home use of pesticides explained only a modest amount of the variability in pesticide concentrations (4–28%).

Conclusions: Agricultural pesticide use near residences was a significant determinant of concentrations of pesticides in carpet dust for five of seven pesticides evaluated.

Background

Exploring spatial-temporal patterns of disease incidence through cluster analysis identifies areas of significantly elevated or decreased risk, providing potential clues about disease risk factors. Little is known about the etiology of non-Hodgkin lymphoma (NHL), or the latency period that might be relevant for environmental exposures, and there are no published spatial-temporal cluster studies of NHL.

Methods

We conducted a population-based case-control study of NHL in four National Cancer Institute (NCI)-Surveillance, Epidemiology, and End Results (SEER) centers: Detroit, Iowa, Los Angeles, and Seattle during 1998-2000. Using 20-year residential histories, we used generalized additive models adjusted for known risk factors to model spatially the probability that an individual had NHL and to identify clusters of elevated or decreased NHL risk. We evaluated models at five different time periods to explore the presence of clusters in a time frame of etiologic relevance.

Results

The best model fit was for residential locations 20 years prior to diagnosis in Detroit, Iowa, and Los Angeles. We found statistically significant areas of elevated risk of NHL in three of the four study areas (Detroit, Iowa, and Los Angeles) at a lag time of 20 years. The two areas of significantly elevated risk in the Los Angeles study area were detected only at a time lag of 20 years. Clusters in Detroit and Iowa were detected at several time points.

Conclusions

We found significant spatial clusters of NHL after allowing for disease latency and residential mobility. Our results show the importance of evaluating residential histories when studying spatial patterns of cancer.

The incidence of non-Hodgkin lymphoma has substantially increased during the past several decades, and although established risk factors such as immunodeficiency and viral infection may be responsible for a portion of the cases, the vast majority of the NHL cases remain unexplained. Dietary nitrate and nitrite intake are exposures of particular interest for non-Hodgkin lymphoma risk as they have been shown to cause lymphomas in animal studies and there is growing evidence of adverse impact in the epidemiological literature. We investigated NHL risk in general and by subtype in relation to dietary nitrate and nitrite intake in a population-based case-control study of 1,304 women in Connecticut. Nitrate and nitrite intake was assessed using a 120-item food frequency questionnaire. We found no association between risk of NHL and dietary nitrate and a slightly increased risk of NHL for higher dietary nitrite intake (OR = 1.37; 95% CI: 1.04–1.79). The risk was significantly increased for diffuse large B-cell lymphoma (OR = 1.61; 95% CI: 1.08–2.42), follicular lymphoma (OR = 1.61; 95% CI: 1.02–2.54), and T-cell lymphoma (OR = 2.38; 95% CI: 1.12–5.06). Animal products containing nitrite appear to be driving the risk for DLBC lymphoma and follicular lymphoma, whereas the risk for T-cell lymphoma is being driven by plant products. Our results confirm a previous finding for nitrite intake and highlight the importance of evaluating NHL risk by histologic type. We conclude that these results should be replicated in a larger study with data on water consumption as well as diet.

Objectives

We used data from a large, population-based case-control study in New England to examine relationships between occupation, industry, and bladder cancer risk.

Methods

Lifetime occupational histories were obtained by personal interview from 1,158 patients newly diagnosed with urothelial carcinoma of the bladder between 2001 and 2004 among residents of Maine, New Hampshire, and Vermont, and from 1,402 population controls selected from Department of Motor Vehicle records (ages 30 to 64 years) or Medicare beneficiary records (65 to 79 years). Unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for demographic factors, smoking, and employment in high-risk occupations other than the one being analyzed.

Results

Male precision metalworkers and metalworking/plasticworking machine operators had significantly elevated risks and significant trends in risk with duration of employment (precision metalworkers: OR=2.2; CI: 1.4, 3.4, Ptrend =0.0065; metalworking/plasticworking machine operators: OR=1.6; CI: 1.01, 2.6, Ptrend=0.047). Other occupations/industries for which risk increased significantly with duration of employment included: for men, textile machine operators, mechanics/repairers, automobile mechanics, plumbers, computer systems analysts, information clerks, and landscape and horticultural services industry workers; and for women, service occupations, health services, cleaning and building services, management-related occupations, electronic components and accessories manufacturing, and transportation equipment manufacturing. Men reporting use of metalworking fluids (MWF) had a significantly elevated bladder cancer risk (OR=1.7; 95% CI: 1.1, 2.5),

Conclusions

Our findings for metalworkers and for MWF exposure support the hypothesis that some component(s) of MWF may be carcinogenic to the bladder in humans. Our results also corroborate many other previously-reported associations between bladder cancer risk and various occupations. More detailed analyses using information collected in job-specific questionnaires administered in this study may help to identify components of MWF that may be carcinogenic, and other bladder carcinogens to which people are exposed in a variety of occupations.

Although the relation between red and processed meat intake and colorectal cancer has been reported in several epidemiologic studies, very few investigated the potential mechanisms. This study examined multiple potential mechanisms in a large U.S. prospective cohort with a detailed questionnaire on meat type and meat cooking methods linked to databases for estimating intake of mutagens formed in meats cooked at high temperatures (heterocyclic amines, polycyclic aromatic hydrocarbons), heme iron, nitrate and nitrite. During 7 years of follow-up, 2,719 colorectal cancer cases were ascertained from a cohort of 300,948 men and women. The hazard ratios (HR) and 95% confidence intervals (CI) comparing the fifth to the first quintile for both red (HR=1.24, 95% CI: 1.09-1.42; p-trend <0.001) and processed meat (HR=1.16, 95% CI: 1.01-1.32; p-trend=0.017) intake indicated an elevated risk for colorectal cancer. The potential mechanisms for this relation include heme iron (HR=1.13, 95% CI: 0.99-1.29; p-trend=0.022), nitrate from processed meats (HR=1.16, 95% CI: 1.02-1.32; p-trend=0.001) and heterocyclic amine intake (HR=1.19, 95% CI: 1.05-1.34; p-trend <0.001 for MeIQx and HR=1.17, 95% CI: 1.05-1.29; p-trend <0.001 for DiMeIQx). In general, the elevated risks were higher for rectal cancer than for colon cancer, with the exception of MeIQx and DiMeIQx, which were only associated with colon cancer. In conclusion, we found a positive association for red and processed meat intake and colorectal cancer; heme iron, nitrate/nitrite, and heterocyclic amines from meat may explain these associations.

Estimation of human exposures to polycyclic aromatic hydrocarbons (PAHs) is often desired for the epidemiological studies of cancer. One way to obtain information about indoor levels of PAHs is to measure these chemicals in house dust. In this study, we evaluated the predictive value of self-reported and geographic data for estimating measured levels of nine PAHs in house dust from 583 households in the Northern California Childhood Leukemia Study (NCCLS). Using multivariable linear regression models, we evaluated the effects on house-dust PAH concentrations from the following covariates: residential heating sources, smoking habits, house characteristics, and outdoor emission sources. House dust was collected from 2001 to 2007, usingboth high-volume surface samplers and household vacuum cleaners, and was analyzed for nine PAHs using gas chromatography-mass spectrometry. All nine PAHs were detected in more than 93% of dust samples, with median concentrations ranging from 14 to 94 ng/g dust. Statistically significant effects on PAH concentrations in house dust were found for gas heating, outdoor PAH concentrations, and residence age. Yet, the optimal regression model only explained 15% of the variation in PAH levels in house dust. As self-reported data and outdoor PAH sources were only marginally predictive of observed PAH levels, we recommend that PAH concentrations be measured directly in dust samples for use in epidemiological studies.