Biomedical subjects

Joanne S Colt

Publications and source records attributed to Joanne S Colt.

18 recordsLinked to original sources

PubMed2006

Ultraviolet radiation, dietary vitamin D, and risk of non-Hodgkin lymphoma (United States).

OBJECTIVE: Because of conflicting findings about the relationship between ultraviolet (UV) radiation and the risk of non-Hodgkin lymphoma (NHL), we evaluated the risk of several indicators related to UV, including two not previously studied: dietary vitamin D, and ambient UV levels by residential location. METHODS: As part of a case-control study conducted in four Surveillance, Epidemiology, and End Results (SEER) registries, we collected UV information from a self-administered questionnaire and computer-assisted personal interview with 551 NHL cases and 462 controls. We estimated the relative risk (RR) and 95% confidence intervals (CI) from unconditional logistic regression models. RESULTS: Eye color, a marker of host susceptibility to UV, showed a decreasing risk gradient for lightest eyes (0.47) compared to darkest. Relative risks were in the range of 0.73-0.78 for participants reporting more hours in the mid-day summer sun. Use of sunlamps or tanning booths was associated with decreased risk (RR = 0.88), as was estimated overall ambient UV (RR = 0.76 per 50 RB-units) overall. Vitamin D intake from diet and supplements was not related to risk. Results were thus consistent for the various indicators, although some estimated risks were not statistically significant. Effects were generally similar for diffuse large B-cell (DLBCL) and follicular lymphomas. CONCLUSION: These data suggest a slight protective effect of sunlight against NHL, and they agree with geographic patterns of NHL incidence observed in the US.

Adult↗

PubMed2006

Risk of non-Hodgkin lymphoma and nitrate and nitrite from drinking water and diet.

INTRODUCTION: Nitrate and nitrite are precursors in the in vivo formation of N-nitroso compounds, potent animal carcinogens. METHODS: We conducted a population-based case-control study of non-Hodgkin lymphoma (NHL) in 1998 to 2000 in Iowa, Detroit, Seattle, and Los Angeles. Because nitrate levels were elevated in many drinking water supplies in Iowa, but not in the other study centers, we evaluated water nitrate levels and risk of NHL in Iowa only. Monitoring data for public supplies were linked to water source histories from 1960 onward. Nitrate was measured at interview homes with private wells. We limited most analyses to those with nitrate estimates for > 70% of their person-years since 1960 (181 cases, 142 controls). For those in the diet arm of the study (458 cases, 383 controls from 4 centers) and for Iowa participants in both the diet and drinking water analyses, we estimated dietary nitrate and nitrite intake using a 117-item food-frequency questionnaire that included foods high in nitrate and nitrite. Odds ratios and 95% confidence intervals were calculated using logistic regression, adjusting for the study matching factors, education, and caloric intake (diet analyses only). RESULTS: We found no overall association with the highest quartile of average drinking water nitrate (> 2.90 mg/L nitrate-N: odds ratios = 1.2; 95% confidence interval = 0.6-2.2) or with years > or = 5 mg/L (10+ years: 1.4; 0.7-2.9). We observed no evidence of an interaction between drinking water nitrate exposure and either vitamin C or red meat intake, an inhibitor and precursor, respectively, of N-nitroso compound formation. Among those in the diet arm, dietary nitrate was inversely associated with risk of NHL (highest quartile: 0.54; 0.34-0.86). Dietary nitrite intake was associated with increasing risk (highest quartile: 3.1; 1.7-5.5) largely due to intakes of bread and cereal sources of nitrite. CONCLUSION: Average drinking water nitrate levels below 3 mg/L were not associated with NHL risk. Our study had limited power to evaluate higher levels that deserve further study.

Aged↗

PubMed2006

Residential insecticide use and risk of non-Hodgkin's lymphoma.

Previous studies have linked non-Hodgkin's lymphoma (NHL) with occupational exposure to insecticides, but residential use is largely unexplored. In this population-based case-control study, we examined NHL risk and use of insecticides in the home and garden. We identified NHL cases, uninfected with HIV, diagnosed between 1998 and 2000 among women and men ages 20 to 74 years in Iowa and the metropolitan areas of Los Angeles, Detroit, and Seattle. Controls were selected using random digit dialing or Medicare files. Computer-assisted personal interviews (1,321 cases and 1,057 controls) elicited data on insecticide use at each home occupied since 1970. Insecticide levels were measured in dust taken from used vacuum cleaner bags (682 cases and 513 controls). We previously reported a positive association with dichlorodiphenyldichloroethylene levels in carpet dust residues. Here, we focus on insecticides that were commonly used after 1970, the time period covered by our questionnaire. People whose homes were treated for termites had elevated NHL risk (odds ratio, 1.3; 95% confidence interval, 1.0-1.6). Risk was modestly, although not significantly, elevated in all but one study center and in all sexes and races. The elevation in risk was restricted to people whose homes were treated before the 1988 chlordane ban. There was a significant trend of increasing risk with increasing levels of alpha-chlordane residues in dust (P(trend) = 0.04) and a marginally significant trend for gamma-chlordane (P(trend) = 0.06). We found no evidence of associations for insects overall, for specific types of insects other than termites, or for elevated residues of other insecticides. We concluded that chlordane treatment of homes for termites may increase residents' NHL risk.

Adult↗

PubMed2006

Proximity to crops and residential exposure to agricultural herbicides in iowa.

Rural residents can be exposed to agricultural pesticides through the proximity of their homes to crop fields. Previously, we developed a method to create historical crop maps using a geographic information system. The aim of the present study was to determine whether crop maps are useful for predicting levels of crop herbicides in carpet dust samples from residences. From homes of participants in a case-control study of non-Hodgkin lymphoma in Iowa (1998-2000), we collected vacuum cleaner dust and measured 14 herbicides with high use on corn and soybeans in Iowa. Of 112 homes, 58% of residences had crops within 500 m of their home, an intermediate distance for primary drift from aerial and ground applications. Detection rates for herbicides ranged from 0% for metribuzin and cyanazine to 95% for 2,4-dichlorophenoxyacetic acid. Six herbicides used almost exclusively in agriculture were detected in 28% of homes. Detections and concentrations were highest in homes with an active farmer. Increasing acreage of corn and soybean fields within 750 m of homes was associated with significantly elevated odds of detecting agricultural herbicides compared with homes with no crops within 750 m (adjusted odds ratio per 10 acres = 1.06; 95% confidence interval, 1.02-1.11). Herbicide concentrations also increased significantly with increasing acreage within 750 m. We evaluated the distance of crop fields from the home at < 100, 101-250, 251-500, and 501-750 m. Including the crop buffer distance parameters in the model did not significantly improve the fit compared with a model with total acres within 750 m. Our results indicate that crop maps may be a useful method for estimating levels of herbicides in homes from nearby crop fields.

Case-Control Studies↗

PubMed2005

Persistent organochlorine chemicals in plasma and risk of non-Hodgkin's lymphoma.

Polychlorinated biphenyls (PCB) have been suspected as possible contributors to increasing non-Hodgkin's lymphoma incidence during the latter half of the 20th century based on their toxicologic properties and provocative epidemiologic reports. We investigated PCBs and other organochlorines and risk of non-Hodgkin's lymphoma in a population-based case-control study in the United States. Congeners of PCBs (including coplanar congeners), dioxins, furans and pesticides or pesticide metabolites were measured in plasma of 100 untreated cases and 100 control subjects. We used a multiple imputation procedure to fill in missing values of levels determined to be below the detection limits. Risks of non-Hodgkin's lymphoma associated with each analyte were estimated using conditional logistic regression for the continuous measure, exposure quartiles, trend across quartile categories, and exposures above the 95th percentile. Certain PCB congeners were associated with increased risk of non-Hodgkin's lymphoma, including coplanar PCBs 156, 180, and 194, with odds ratios for the highest versus lowest quartile ranging from 2.7 to 3.5, and significant trends. Each of the furan congeners was associated with risk of non-Hodgkin's lymphoma, as were total furans, with 3.5-fold increased risk for the highest versus lowest quartile and a significant trend across quartiles (P = 0.006). The toxic equivalency quotient (TEQ), a summed metric that weights congeners by their dioxin-like potency, was associated with non-Hodgkin's lymphoma, with 35% increased risk per 10 TEQ pg/g lipid (95% confidence interval, 1.02-1.79). Our results add to existing literature, which suggests that exposure to organochlorines contributes to non-Hodgkin's lymphoma risk; these risks were most apparent for certain PCBs and furans.

Adult↗

PubMed2005

Immune-related conditions and immune-modulating medications as risk factors for non-Hodgkin's lymphoma: a case-control study.

In immunosuppressed or autoimmune disease states, disordered immune responses may lead to non-Hodgkin's lymphoma (NHL). In a US population-based case-control study of NHL (1998-2000), the authors collected personal histories of immune-related conditions and use of immune-modulating therapies as well as family histories of autoimmune conditions. The study included 1,321 NHL cases and 1,057 controls; only half received some questionnaire components. NHL was associated with Sjögren's syndrome (odds ratio (OR) = 13, 95% confidence interval (CI): 1.7, 100) and lupus (OR = 4.2, 95% CI: 1.2, 15). Two specific NHL subtypes were strongly associated with Sjögren's syndrome: salivary gland (OR = 290, 95% CI: 33, 2600) and marginal zone (OR = 75, 95% CI: 9.1, 610). NHL was less convincingly associated with receipt of an organ transplant (OR = 2.0, 95% CI: 0.4, 11). Other autoimmune conditions were too rare to evaluate or not associated with NHL. Corticosteroid use was unrelated to NHL (OR = 1.0, 95% CI: 0.8, 1.2), but methotrexate use was marginally associated (OR = 2.3, 95% CI: 0.7, 7.5). Family history of dermatomyositis was associated with NHL (7 cases vs. 0 controls, OR = infinite; two-sided p = 0.02), but dermatomyositis was absent in cases themselves. Family history of remaining conditions was unrelated to NHL. Results suggest that disordered immunity in some immune-related conditions can lead to NHL.

Adult↗

PubMed2005

Meat and meat-mutagen intake and risk of non-Hodgkin lymphoma: results from a NCI-SEER case-control study.

Non-Hodgkin Lymphoma (NHL) incidence has risen dramatically over past decades, but the reasons for most of this increase are not known. Meat cooked well-done using high-temperature cooking techniques produces heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (B[a]P). This study was conducted as a population-based case-control study in Iowa, Detroit, Seattle and Los Angeles and was designed to determine whether meat, meat-cooking methods, HCAs or PAHs from meat were associated with NHL risk. This study consisted of 458 NHL cases, diagnosed between 1998 and 2000, and 383 controls. Participants completed a 117-item food frequency questionnaire (FFQ), with graphical aids to assess the meat-cooking method and doneness level, which was linked to a HCA and B[a]P database. Logistic regression, comparing the fourth to the first quartile, found no association between red meat or processed meat intake and risk for NHL [odds ratio (OR) and 95% confidence interval (CI): 1.10 (0.67-1.81) and 1.18 (0.74-1.89), respectively]. A marginally significant elevated risk for NHL was associated with broiled meat [OR and 95% CI: 1.32 (0.99-1.77); P trend = 0.09], comparing those who consumed broiled meat with those who did not. The degree to which meat was cooked was not associated with the risk for NHL, although one of the HCAs, DiMeIQx (2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline), was associated with an inverse risk. Fat intake was associated with a significantly elevated risk for NHL [OR and 95% CI: 1.60 (1.05-2.45); P trend = 0.12]; in contrast, animal protein was inversely associated with risk for NHL [OR and 95% CI: 0.39 (0.22-0.70); P trend = 0.004]. Overall, our study suggests that consumption of meat, whether or not it is well-done, does not increase the risk of NHL. Furthermore, neither HCAs nor B[a]P from meat increase the risk of NHL.

Adult↗

PubMed2005

Anthropometrics, physical activity, related medical conditions, and the risk of non-hodgkin lymphoma.

BACKGROUND: Recent reports suggest that obesity, or conditions associated with obesity, might be risk factors for non-Hodgkin lymphoma (NHL), a cancer with dramatically increasing incidence in western countries over the last several decades. Physical inactivity increases the risk of obesity and of type 2 diabetes, but there are few data on the association of physical activity with risk of NHL. METHODS: We evaluated these factors in a population-based case-control study conducted in Detroit, Iowa, Los Angeles, and Seattle from 1998 to 2000. Incident HIV-negative NHL cases aged 20-74 years were rapidly reported in each area (n = 1321). Controls were identified through random digit dialing and Medicare files, and were frequency matched to cases on sex, age, race, and study site (n = 1057). Risk factor data were collected by in-person interviews and self-administered questionnaires. Unconditional logistic regression was used to estimate the odds ratio (OR) and 95% confidence intervals (CI), adjusted for age, sex, race and study center. RESULTS: High body mass index (OR = 1.73 for 35+ versus <25 kg/m2; 95% CI 1.15-2.59) and history of gallstones (OR = 1.95, 95% CI 1.11-3.40) were positively associated with diffuse NHL, but were not associated with follicular or all NHL combined. Height was positively associated with risk of all NHL combined (OR = 1.38 for >70 versus <65 inches; 95% CI 0.98-1.94), and positive associations were apparent for both diffuse and follicular NHL. Non-occupational physical activity was inversely associated with risk of all NHL combined (ORs with increasing level: 1, 0.75, 0.71, 0.55, 0.68; p-trend = 0.04) and for diffuse and follicular NHL. We observed no association of total energy intake, type 2 diabetes, or hypertension with risk of NHL. In a multivariable model to predict risk of diffuse NHL, BMI (OR = 2.15 for 35+ versus <25 kg/m2; 95% CI 1.09-4.25) and height (OR = 1.63 for 71+ versus <65 inches; 95% CI 0.75-3.57) were positively associated with risk while physical activity was weakly and inversely associated risk (ORs with increasing level: 1, 0.76, 0.72, 0.78, 0.82; p-trend = 0.9). CONCLUSION: BMI and history of gallstones were positively associated with risk of diffuse NHL, supporting a role for obesity in this NHL subtype. Height was positively associated with NHL risk across subtypes, and suggests a role for early life nutrition in NHL risk. Non-occupational physical activity was only weakly and inversely associated with NHL risk after adjustment for obesity, height and alcohol use.

Adult↗

PubMed2005

Response rates in a case-control study: effect of disclosure of biologic sample collection in the initial contact letter.

PURPOSE: Participants in epidemiology studies are often asked to complete an interview and to provide biospecimens. In a population-based case-control study of kidney cancer involving an interview and optional biospecimens, we examined whether mentioning the biospecimens in the initial contact letter adversely affects willingness to be interviewed. METHODS: Eligible cases (n = 434) and controls (n = 775) in Detroit were alternately assigned to receive one of two versions of the contact letter. Both explained that the study involves an interview with 100 dollars compensation plus an optional component with additional compensation; only one disclosed that the optional component involved biospecimens. RESULTS: There were no meaningful differences between the groups in willingness to be interviewed. However, among 303 cases and 351 controls already interviewed, the proportion providing biospecimens was higher in the fully informed group: for blood, the differences were 10.8 (95% CI, 2.0, 19.5) for cases and 6.7% (95% CI, -1.7, 15.1) for controls. Findings were similar for saliva. CONCLUSIONS: In a study involving an interview and optional biospecimens, informing people about the samples in the contact letter seems preferable to a non-specific reference to a second study component. Both approaches yielded similar interview participation rates, but biospecimen participation rates were higher among those informed about the samples in the contact letter.

Adult↗

PubMed2005

Organochlorines in carpet dust and non-Hodgkin lymphoma.

BACKGROUND: The incidence of non-Hodgkin lymphoma (NHL) has risen over the past several decades. Reasons for this increase are largely unexplained. METHODS: In this population-based case-control study, we examined NHL risk and exposure to organochlorine compounds using concentrations in carpet dust as an exposure indicator. We identified NHL cases, uninfected with HIV, diagnosed between 1998 and 2000 among women and men ages 20-74 years in Iowa, Los Angeles County, and the Detroit and Seattle metropolitan areas. Controls were selected using random-digit-dialing or Medicare files. Organochlorine concentrations were measured in vacuum bag dust from 603 white cases and 443 white controls who had owned most of their carpets for at least 5 years. RESULTS: NHL risk was elevated if any of the polychlorinated biphenyl (PCB) congeners (PCBs 105, 138, 153, 170, or 180) was detected (odds ratio = 1.5; 95% confidence interval = 1.2-2.0). Risk was elevated in the top tertile of PCB 180 (1.7; 1.1-2.6) and in the top 2 tertiles of total PCBs (middle tertile, 1.6 [1.1-2.4]; top tertile 1.5 [1.0-2.2]). There was a positive trend in risk with increasing PCB 180 levels (P trend = 0.03). NHL risk was elevated if dichlorodiphenyldichloroethylene (DDE) was detected (1.3; 1.0-1.7), but only among men. A positive, but not monotonic, dose-response relationship was observed for DDE (P trend = 0.02). CONCLUSIONS: Our findings suggest an increased risk of NHL associated with exposure to PCBs, with evidence of greater effects for PCB 180. There is also some evidence of an association with DDE.

Adult↗

PubMed2005

Positional accuracy of two methods of geocoding.

BACKGROUND: Geocoding is often used in epidemiologic studies to map residences with geographic information systems (GIS). The accuracy of the method is usually not determined. METHODS: We collected global positioning system (GPS) measurements at homes in a case-control study of non-Hodgkin lymphoma in Iowa. We geocoded the addresses by 2 methods: (1) in-house, using ArcView 3.2 software and the U.S. Census Bureau TIGER 2000 street database; and (2) automated geocoding by a commercial firm. We calculated the distance between the geocoded and GPS location (positional error) overall and separately for homes within towns and outside (rural). We evaluated the error in classifying homes with respect to their proximity to crop fields. RESULTS: Overall, the majority of homes were geocoded with positional errors of less than 100 m by both methods (ArcView/TIGER 2000, median = 62 m [interquartile range = 39-103]; commercial firm, median = 61 m [interquartile range = 35-137]). For town residences, the percent geocoded with errors of </=100 m was 81% for ArcView/TIGER 2000 and 84% for the commercial firm. For rural residences, a smaller percent of addresses were geocoded with this level of accuracy, especially by the commercial firm (ArcView/TIGER 2000, 56%; commercial firm, 28%). Geocoding errors affected our classification of homes according to their proximity to agricultural fields at 100 m, but not at greater distances (250-500 m). CONCLUSIONS: Our results indicate greater positional errors for rural addresses compared with town addresses. Using a commercial firm did not improve accuracy compared with our in-house method. The effect of geocoding errors on exposure classification will depend on the spatial variation of the exposure being studied.

Adult↗

PubMed2005

Residential herbicide use and risk of non-Hodgkin lymphoma.

CONTEXT: Environmental exposure to herbicides has been hypothesized to contribute to the long-term increase in non-Hodgkin lymphoma (NHL). OBJECTIVE: To estimate the effects of residential herbicide exposure on NHL risk. DESIGN: Population-based case-control study. SETTING: Iowa and metropolitan Detroit, Los Angeles, and Seattle, 1998 to 2000. PARTICIPANTS: NHL patients ages 20 to 74 years and unaffected residents identified by random digit dialing and Medicare eligibility files. MAIN OUTCOME MEASURES: Computer-assisted personal interviews (1,321 cases, 1,057 controls) elicited data on herbicide use at each home occupied since 1970. Levels of 2,4-dichlorophenoxy-acetic acid and dicamba were measured in dust taken from used vacuum cleaner bags in the current home (679 cases, 510 controls who had owned at least half of their carpets for > or = 5 years). RESULTS: Herbicide use on the lawn or garden was similar among cases and controls (adjusted relative risk, 1.02; 95% confidence interval, 0.84-1.23). Estimated risk did not increase with greater duration, frequency, or total number of applications of herbicides to the lawn, the garden, or to both combined. Risk was not elevated for respondents who applied the herbicides themselves and not for those exposed during the 1970s, 1980s, or 1990s. We detected 2,4-dichlorophenoxy-acetic acid equally often in homes of cases and controls (78%). We found dicamba in homes of 15% of cases and 20% of controls. We also found no elevation in risk among the respondents who had the highest dust levels and highest self-reported exposures. We found no consistent patterns for specific histologies. CONCLUSIONS: We found no detectable excess associated with residential exposures. Residential herbicide exposures are unlikely to explain the long-term increase in NHL.

Adult↗

PubMed2004

Case-control study of simian virus 40 and non-Hodgkin lymphoma in the United States.

BACKGROUND: Recent studies have reported detection of simian virus 40 (SV40) DNA in tumor tissues from 15%-43% of U.S. non-Hodgkin lymphoma (NHL) patients. SV40 accidentally contaminated U.S. poliovirus vaccines that were widely administered from 1955 through 1962. However, epidemiologic data linking SV40 with NHL are lacking. METHODS: We obtained serum samples from 724 incident NHL case patients and 622 control subjects from a population-based U.S. case-control study. SV40 serostatus was analyzed by two independent laboratories (designated A and B) using similar virus-like particle (VLP) enzyme immunoassays. Associations with serostatus were assessed with logistic regression, adjusting for sex, race, birth year, and study site. VLPs for the human polyomaviruses BK and JC were used in competitive inhibition experiments to assess the specificity of SV40 reactivity. Statistical tests were two-sided. RESULTS: SV40 antibody results from the two laboratories were correlated (R = 0.59; P<.001). Laboratories A and B detected SV40 seropositivity in 7.2% and 9.8% of NHL case patients, respectively, and in 10.5% and 9.6% of control subjects, respectively. SV40 seropositivity was not associated with increased NHL risk (laboratory A: adjusted odds ratio [OR] = 0.68, 95% confidence interval [CI] = 0.46 to 1.00; laboratory B: adjusted OR = 1.02, 95% CI = 0.71 to 1.47). SV40 seropositivity was not associated with NHLs of any specific histology or site. Among subjects born before 1963, 1.0%-1.6% showed SV40-specific reactivity, i.e., SV40 reactivity confirmed in competitive inhibition experiments, whereas (based on limited data) none born subsequently demonstrated SV40-specific reactivity. CONCLUSIONS: In persons born before 1963, the presence of SV40-specific antibodies, although rare, could reflect exposure to SV40-contaminated vaccines. Nevertheless, NHL risk was unrelated to serologic evidence of SV40 exposure or infection.

Adult↗

PubMed2004

Hepatitis C virus infection and non-Hodgkin lymphoma: results of the NCI-SEER multi-center case-control study.

Several studies have noted elevated hepatitis C virus (HCV) prevalence among patients with non-Hodgkin lymphoma (NHL), suggesting that HCV infection increases NHL risk through chronic immune stimulation. Population-based data from the U.S. are lacking. In a population-based case-control study of NHL in the United States, we identified HCV infection using an enzyme immunoassay, confirmed by recombinant immunoblot assay or HCV RNA detection. The association between HCV and NHL was assessed using logistic regression, adjusting for demographic factors, illicit drug use or medical history. Thirty-two of 813 (3.9%) NHL cases and 14 of 684 (2.1%) controls were HCV-infected [odds ratio (OR) 1.96, 95%CI 1.07-4.03]. For separate NHL subtypes, numbers were limited. Nonetheless, positive associations were noted for follicular (OR 2.46, 95%CI 1.01-5.81), marginal zone (3.99, 0-13.6) and mucosa-associated lymphoid tissue (2.04, 0-7.20) NHLs. For all NHLs combined, the HCV-NHL association changed little after adjustment for sex, age, race and study center (OR 1.89, 95%CI 1.00-4.00). HCV was common in controls who had injected drugs (40%) or used other illicit drugs (6.5%), but adjustment for drug use did not affect the HCV-NHL association (OR 1.87, 95%CI 0.95-4.10). Transfusion history was unrelated to HCV status, and adjustment for this exposure did not attenuate the HCV-NHL association (OR 2.15, 95%CI 1.12-4.76). Excluding 4 subjects with a history of hemodialysis or 3 subjects with organ transplants also did not affect the results. Our study demonstrates an association between HCV infection and NHL in the United States. HCV infection may be a cause of NHL.

Adult↗

PubMed2004

Occupation and bladder cancer risk in a population-based case-control study in New Hampshire.

OBJECTIVE: To identify occupations with excess bladder cancer risk in New Hampshire, where bladder cancer mortality rates have been elevated for decades. METHODS: Lifetime occupational histories were obtained from interviews with 424 cases and 645 controls in a population-based case-control study. Unconditional logistic regression models were used to estimate odds ratios (Ors) and 95% confidence intervals (CI) for each occupation, adjusted for age and smoking. Analyses by duration of employment were carried out and interactions with smoking were examined. RESULTS: Male tractor-trailer truck drivers had an elevated risk for bladder cancer (OR = 2.4, CI = 1.4-4.1), with a significant positive trend in risk with increasing duration of employment (P (trend) = 0.0003). Male metal/plastic processing machine operators also had a significant excess (OR = 4.9, CI = 1.6-15.1), attributable mainly to molding/casting machine operators (OR = 16.6, CI = 2.1-131). Elevated risk was also observed for male fabricators, assemblers, and hand workers (OR = 1.8, CI = 1.0-3.4). Women in certain sales occupations (sales clerks, counter clerks, and cashiers) had a significant excess risk (OR = 2.2, CI = 1.3-3.9) and a significant trend with duration of employment (P (trend) = 0.016), as did female health service workers (OR = 4.1, CI = 1.6-10.7; P (trend) = 0.014). There was a positive interaction between smoking and employment as a health service worker (p = 0.036). CONCLUSIONS: These findings are generally consistent with previous studies. Elevated risks for male molding/casting machine operators, female salesworkers, and female health service workers, especially those with a history of smoking, require further investigation.

Adult↗

PubMed2004

Comparison of pesticide levels in carpet dust and self-reported pest treatment practices in four US sites.

Epidemiologic studies have used both questionnaires and carpet dust sampling to assess residential exposure to pesticides. The consistency of the information provided by these two approaches has not been explored. In a population-based case-control study of non-Hodgkin's lymphoma, carpet dust samples were collected from the homes of 513 control subjects in Detroit, Iowa, Los Angeles, and Seattle. The samples were taken from used vacuum cleaner bags and analyzed for 30 pesticides. Interviewers queried subjects about the types of pests treated in their home using a detailed questionnaire accompanied by visual aids. Geographic variations in pesticide levels were generally consistent with geographic differences in pest treatment practices. Los Angeles residents reported the most treatment for crawling insects, fleas/ticks, and termites, and Los Angeles dust samples had the highest levels of propoxur, chlorpyrifos, diazinon, permethrin, and chlordane. Iowa had the most treatment for lawn/garden weeds, and also the highest levels of 2,4-dichlorophenoxyacetic acid and dicamba. Although Seattle had the highest proportion of subjects treating for lawn/garden insects, the lawn/garden insecticides were higher in other sites. Multivariate linear regression revealed several significant associations between the type of pest treated and dust levels of specific pesticides. The strongest associations were between termite treatment and chlordane, and flea/tick treatment and permethrin. Most of the significant associations were consistent with known uses of the pesticides; few expected associations were absent. The consistency between the questionnaire data and pesticide residues measured in dust lends credibility to both methods for assessing residential exposure to pesticides. The combined techniques appear promising for epidemiologic studies. Interviewing is the only way to assess pesticide exposures before current carpets were in place. Dust sampling provides an objective measure of specific compounds to which a person may have been exposed through personal use of a pesticide or by drift-in or track-in from outside, and avoids recall bias.

Adult↗

PubMed2004

Epidemiologic evaluation of measurement data in the presence of detection limits.

Quantitative measurements of environmental factors greatly improve the quality of epidemiologic studies but can pose challenges because of the presence of upper or lower detection limits or interfering compounds, which do not allow for precise measured values. We consider the regression of an environmental measurement (dependent variable) on several covariates (independent variables). Various strategies are commonly employed to impute values for interval-measured data, including assignment of one-half the detection limit to nondetected values or of "fill-in" values randomly selected from an appropriate distribution. On the basis of a limited simulation study, we found that the former approach can be biased unless the percentage of measurements below detection limits is small (5-10%). The fill-in approach generally produces unbiased parameter estimates but may produce biased variance estimates and thereby distort inference when 30% or more of the data are below detection limits. Truncated data methods (e.g., Tobit regression) and multiple imputation offer two unbiased approaches for analyzing measurement data with detection limits. If interest resides solely on regression parameters, then Tobit regression can be used. If individualized values for measurements below detection limits are needed for additional analysis, such as relative risk regression or graphical display, then multiple imputation produces unbiased estimates and nominal confidence intervals unless the proportion of missing data is extreme. We illustrate various approaches using measurements of pesticide residues in carpet dust in control subjects from a case-control study of non-Hodgkin lymphoma.

Bias↗

PubMed2002

Sampling private wells at past homes to estimate arsenic exposure: a methodologic study in New England.

We are conducting a collaborative, population-based case-control study in Maine, New Hampshire, and Vermont to investigate the reasons for the elevated bladder cancer mortality in northern New England. Arsenic in drinking water is one of the primary exposures under investigation. To estimate subjects' lifetime exposure to waterborne arsenic, it will be necessary to obtain water samples from private wells that subjects used in the past. We conducted a methodologic study to assess the feasibility of locating and sampling from private wells at subjects' past residences. Ninety-eight New Hampshire residents (mean age 67 years) completed a questionnaire requesting the complete address, dates of occupancy, and drinking water sources for each home lived in since birth. An interviewer then asked subjects for more detailed information about each home to assist in a field search of past homes in the three-state study area of Maine, New Hampshire, and Vermont. Fifty-eight of the 98 subjects indicated that they had used a total of 103 private wells in 95 previous homes located in these three states. We conducted a field search to locate these 95 homes, visited town offices to find the properties on tax maps and obtain the current owners' names and addresses, attempted to obtain permission from the current owners to sample the wells, and collected water samples. In all, 48 (47%) of the 103 past wells in the study area were sampled successfully. The remaining wells were not sampled because the homes were not located (22%) or had been demolished (2%), permission to sample the wells was not obtained (17%), the wells had been destroyed (7%) or could not be found on the grounds of the residence (3%), or for other reasons (2%). Various approaches for improving the success rates for sampling water from private wells are discussed, as is the use of predictive modeling to impute exposures when sampling is not feasible.

Adult↗