Early life exposure to phthalates and the development of childhood asthma among Canadian children.

BACKGROUND: Studies have demonstrated an association between phthalate exposure and childhood asthma, although results have been inconsistent. No epidemiological studies have examined exposure during the first year of life. OBJECTIVE: To investigate the association between phthalate exposures in the home environment during the first year of life, and subsequent development of childhood asthma and related symptoms. METHODS: This study used a case-cohort design including 436 randomly selected children and all additional cases of asthma at 5 years (ntotal = 129) and recurrent wheeze between 2 and 5 years (ntotal = 332) within the CHILD Cohort Study, a general population Canadian birth cohort of 3455 children. Phthalate exposure was assessed using house dust samples collected during a standardized home visit when children were 3-4 months of age. All children were assessed by specialist clinicians for asthma and allergy at 1, 3 and 5 years. Logistic regression was used to assess the association between exposure to five phthalates and asthma diagnosis at 5 years, and recurrent wheeze between 2 and 5 years, with further stratification by wheeze subtypes (late onset, persistent, transient) based on the timing of onset and persistence of wheeze symptoms. RESULTS: Di(2-ethylhexyl) phthalate (DEHP) had the highest concentration in dust (mediansubcohort = 217 µg/g), followed by benzyl butyl phthalate (BzBP) (20 µg/g). A nearly four-fold increase in risk of developing asthma was associated with the highest concentration quartile of DEHP (OR = 3.92, 95% CI: 1.87-8.24) including a positive dose-response relationship. A two-fold increase in risk of recurrent wheeze was observed across all quartiles compared to the lowest quartile of DEHP concentrations. Compared to other wheeze subtypes, stronger associations for DEHP were observed with the late onset wheezing subtype, while stronger associations for di-iso-butyl phthalate (DiBP) and BzBP were observed with the transient subtype. DISCUSSION: DEHP exposure at 3-4 months, at concentrations lower than other studies that reported an association, were associated with increased risks of asthma and recurrent wheeze among children at 5 years. These findings suggest the need to assess whether more stringent regulations are required to protect children's health, which can be informed by future work exploring the main sources of DEHP exposure.

Insecticide use and risk of non-Hodgkin lymphoma subtypes: A subset meta-analysis of the North American Pooled Project.

Insecticide use has been linked to increased risk of non-Hodgkin lymphoma (NHL), however, findings of epidemiologic studies have been inconsistent, particularly for NHL subtypes. We analyzed 1690 NHL cases and 5131 controls in the North American Pooled Project (NAPP) to investigate self-reported insecticide use and risk of NHL overall and by subtypes: follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL) and small lymphocytic lymphoma (SLL). Odds ratios (OR) and 95% confidence intervals for each insecticide were estimated using logistic regression. Subtype-specific associations were evaluated using ASSET (Association analysis for SubSETs). Increased risks of multiple NHL subtypes were observed for lindane (OR = 1.60, 1.20-2.10: FL, DLCBL, SLL), chlordane (OR = 1.59, 1.17-2.16: FL, SLL) and DDT (OR = 1.36, 1.06-1.73: DLBCL, SLL). Positive trends were observed, within the subsets with identified associations, for increasing categories of exposure duration for lindane (Ptrend = 1.7 × 10-4 ), chlordane (Ptrend = 1.0 × 10-3 ) and DDT (Ptrend = 4.2 × 10-3 ), however, the exposure-response relationship was nonlinear. Ever use of pyrethrum was associated with an increased risk of FL (OR = 3.65, 1.45-9.15), and the relationship with duration of use appeared monotonic (OR for >10 years: OR = 5.38, 1.75-16.53; Ptrend = 3.6 × 10-3 ). Our analysis identified several novel associations between insecticide use and specific NHL subtypes, suggesting possible etiologic heterogeneity in the context of pesticide exposure.

Pesticide use and risk of Hodgkin lymphoma: results from the North American Pooled Project (NAPP).

PURPOSE: The purpose of this study was to investigate associations between pesticide exposures and risk of Hodgkin lymphoma (HL) using data from the North American Pooled Project (NAPP). METHODS: Three population-based studies conducted in Kansas, Nebraska, and six Canadian provinces (HL = 507, Controls = 3886) were pooled to estimate odds ratios and 95% confidence intervals for single (never/ever) and multiple (0, 1, 2-4, ≥ 5) pesticides used, duration (years) and, for select pesticides, frequency (days/year) using adjusted logistic regression models. An age-stratified analysis (≤ 40/ > 40 years) was conducted when numbers were sufficient. RESULTS: In an analysis of 26 individual pesticides, ever use of terbufos was significantly associated with HL (OR: 2.53, 95% CI 1.04-6.17). In age-stratified analyses, associations were stronger among those ≤ 40 years of age. No significant associations were noted among those > 40 years old; however, HL cases ≤ 40 were three times more likely to report ever using dimethoate (OR: 3.76 95% CI 1.02-33.84) and almost twice as likely to have ever used malathion (OR: 1.86 95% CI 1.00-3.47). Those ≤ 40 years of age reporting use of 5 + organophosphate insecticides had triple the odds of HL (OR: 3.00 95% CI 1.28-7.03). Longer duration of use of 2,4-D, ≥ 6 vs. 0 years, was associated with elevated odds of HL (OR: 2.59 95% CI 1.34-4.97). CONCLUSION: In the NAPP, insecticide use may increase the risk of HL, but results are based on small numbers.

Silica and asbestos exposure at work and the risk of bladder cancer in Canadian men: a population-based case-control study.

BACKGROUND: Silica and asbestos are recognized lung carcinogens. However, their role in carcinogenesis at other organs is less clear. Clearance of inhaled silica particles and asbestos fibers from the lungs may lead to translocation to sites such as the bladder where they may initiate carcinogenesis. We used data from a Canadian population-based case-control study to evaluate the associations between these workplace exposures and bladder cancer. METHODS: Data from a population-based case-control study were used to characterize associations between workplace exposure to silica and asbestos and bladder cancer among men. Bladder cancer cases (N = 658) and age-frequency matched controls (N = 1360) were recruited within the National Enhanced Cancer Surveillance System from eight Canadian provinces (1994-97). Exposure concentration, frequency and reliability for silica and asbestos were assigned to each job, based on lifetime occupational histories, using a combination of job-exposure profiles and expert review. Exposure was modeled as ever/never, highest attained concentration, duration (years), highest attained frequency (% worktime) and cumulative exposure. Odds ratios (OR) and their 95% confidence intervals (CI) were estimated using adjusted logistic regression. RESULTS: A modest (approximately 20%) increase in bladder cancer risk was found for ever having been exposed to silica, highest attained concentration and frequency of exposure but this increase was not statistically significant. Relative to unexposed, the odds of bladder cancer were 1.41 (95%CI: 1.01-1.98) times higher among men exposed to silica at work for ≥27 years. For asbestos, relative to unexposed, an increased risk of bladder cancer was observed for those first exposed ≥20 years ago (OR:2.04, 95%CI:1.25-3.34), those with a frequency of exposure of 5-30% of worktime (OR:1.45, 95%CI:1.06-1.98), and for those with < 10 years of exposure at low concentrations (OR:1.75, 95%CI:1.10-2.77) and the lower tertile of cumulative exposure (OR:1.69, 95%CI:1.07-2.65). However, no clear exposure-response relationships emerged. CONCLUSIONS: Our results indicate a slight increase in risk of bladder cancer with exposure to silica and asbestos, suggesting that the effects of these agents are broader than currently recognized. The findings from this study inform evidence-based action to enhance cancer prevention efforts, particularly for workers in industries with regular exposure.

Exposure to crystalline silica in Canadian workplaces and the risk of kidney cancer.

OBJECTIVES: The causes of kidney cancer are not well understood though occupational exposures are thought to play a role. Crystalline silica is a known human carcinogen, and despite previous links with kidney disease, there have been few studies investigating its association with kidney cancer. We addressed this research gap using a population-based case-control study of Canadian men. METHODS: Questionnaire data were obtained from individuals with histologically confirmed kidney cancer, and population-based controls recruited from eight Canadian provinces (1994-1997). An industrial hygienist characterised participants' lifetime occupational exposure, and their confidence in the assessment (possibly, probably or definitely exposed) to silica on three dimensions (intensity, frequency and duration), and cumulative exposure was estimated. Logistic regression was used to estimate ORs and 95% CIs, adjusting for potential confounders. RESULTS: Nearly half of the 689 kidney cancer cases (49%) and 2369 controls (44%) had ever been occupationally exposed to crystalline silica. In a fully adjusted model, workers ever-exposed to silica had a slightly increased risk of kidney cancer relative to those who were unexposed (OR 1.10, 95% CI 0.92 to 1.32). Odds were modestly (and generally not statistically significantly) increased for models with duration of exposure and cumulative exposure, though exposure-response relationships were not evident. CONCLUSIONS: Our findings do not provide evidence that occupational exposure to crystalline silica increases risk of kidney cancer in men.

Prostate cancer in firefighting and police work: a systematic review and meta-analysis of epidemiologic studies.

OBJECTIVES: We conducted a systematic review and meta-analysis to evaluate potential associations between firefighting and police occupations, and prostate cancer incidence and mortality. METHODS: Original epidemiological studies published from 1980 to 2017 were identified through PubMed and Web of Science. Studies were included if they contained specific job titles for ever/never firefighting and police work and associated prostate cancer risk estimates with 95% confidence intervals (CI). Study quality was assessed using a 20-point checklist. Prostate cancer meta-risk estimates (mRE) and corresponding 95% CIs were calculated for firefighting and police work separately and by various study characteristics using random effects models. Between-study heterogeneity was evaluated using the I2 score. Publication bias was assessed using Begg's and Egger's tests. RESULTS: A total of 26 firefighter and 12 police studies were included in the meta-analysis, with quality assessment scores ranging from 7 to 19 points. For firefighter studies, the prostate cancer incidence mRE was 1.17 (95% CI = 1.08-1.28, I2 = 72%) and the mortality mRE was 1.12 (95% CI = 0.92-1.36, I2 = 50%). The mRE for police incidence studies was 1.14 (95% CI = 1.02-1.28; I2 = 33%); for mortality studies, the mRE was 1.08 (95% CI = 0.80-1.45; I2 = 0%). By study design, mREs for both firefighter and police studies were similar to estimates of incidence and mortality. CONCLUSION: Small excess risks of prostate cancer were observed from firefighter studies with moderate to substantial heterogeneity and a relatively small number of police studies, respectively. There is a need for further studies to examine police occupations and to assess unique and shared exposures in firefighting and police work.

Pesticide exposures and the risk of multiple myeloma in men: An analysis of the North American Pooled Project.

Multiple myeloma (MM) has been consistently linked with agricultural activities, including farming and pesticide exposures. Three case-control studies in the United States and Canada were pooled to create the North American Pooled Project (NAPP) to investigate associations between pesticide use and haematological cancer risk. This analysis used data from 547 MM cases and 2700 controls. Pesticide use was evaluated as follows: ever/never use; duration of use (years); and cumulative lifetime-days (LD) (days/year handled × years of use). Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression adjusted for age, province/state of residence, use of proxy respondents and selected medical conditions. Increased MM risk was observed for ever use of carbaryl (OR = 2.02, 95% CI = 1.28-3.21), captan (OR = 1.98, 95% CI = 1.04-3.77) and DDT (OR = 1.44, 95% CI = 1.05-1.97). Using the Canadian subset of NAPP data, we observed a more than threefold increase in MM risk (OR = 3.18, 95% CI = 1.40-7.23) for ≤10 cumulative LD of carbaryl use. The association was attenuated but remained significant for >10 LD of carbaryl use (OR = 2.44; 95% CI = 1.05-5.64; ptrend = 0.01). For captan, ≤17.5 LD of exposure was also associated with a more than threefold increase in risk (OR = 3.52, 95% CI = 1.32-9.34), but this association was attenuated in the highest exposure category of >17.5 LD (OR = 2.29, 95% CI = 0.81-6.43; ptrend = 0.01). An increasing trend (ptrend = 0.04) was observed for LD of DDT use (LD > 22; OR = 1.92, 95% CI = 0.95-3.88). In this large North American study of MM and pesticide use, we observed significant increases in MM risk for use of carbaryl, captan and DDT.

Natural resource-based industries and prostate cancer risk in Northeastern Ontario: a case-control study.

OBJECTIVE: Prostate cancer continues to be the most commonly diagnosed cancer in men, and there is limited knowledge on its preventable risk factors. A number of occupational exposures in natural resource-based industries are suspected to be related to prostate cancer risk. This study investigates associations between employment in these industries and prostate cancer. METHODS: Data were from a population-based, case-control study previously conducted in Northeastern Ontario. Incident cases (N=760) aged 45-85 years and diagnosed with prostate cancer between 1995 and 1998 were identified from the Ontario Cancer Registry. Controls (N=1632) were recruited using telephone listings, and were frequency matched to cases by age. Lifetime occupational history was collected for all participants. Logistic regression was used to estimate ORs and their associated 95% CIs. RESULTS: Elevated risks were observed for employment in forestry and logging industries (OR=1.87, 95% CI 1.32 to 2.73) and occupations (OR=1.71, 95% CI 1.24 to 2.35), and these risks increased with duration of employment for ≥10 years. Elevated risks were also found for employment in wood products industries (OR=1.45, 95% CI 1.07 to 1.97), and paper and allied products industries (OR=1.43, 95% CI 1.03 to 2.00), and when duration of employment was ≥10 years. There were also elevated risks in agriculture and mining-related work; however, these findings were not consistent across industry and occupation categories. CONCLUSIONS: Prostate cancer risk may be associated with work in several natural resource industries, primarily in the forest industries. To further evaluate observed associations, studies should focus on natural resource-based exposures in larger populations with improved exposure assessment.

Workplace exposure to diesel and gasoline engine exhausts and the risk of colorectal cancer in Canadian men.

BACKGROUND: The International Agency for Research on Cancer (IARC) classified diesel exhaust as carcinogenic to humans (Group 1) and gasoline exhaust as a possible carcinogen (Group 2B) based studies of lung cancer, however the evidence for other sites is limited. We addressed this question by investigating exposure to diesel and gasoline emissions with respect to risk of colorectal cancer in men. METHODS: We used data from a population-based case-control study with incident cases of colon (n = 931) and rectal (n = 840) cancer and 1360 controls from 7 Canadian provinces conducted in 1994-1997. Lifetime occupational history and information on other risk factors was collected. Occupational hygienists, blinded to case-control status, assigned exposures to each job for 3 dimensions: concentration, frequency, and reliability. Logistic regression was used to estimate odds ratios (OR) and their 95 % confidence intervals (CI), adjusted for age, province, use of proxy respondents, smoking, body-mass index, physical activity, intake of alcohol, processed meats, and occupational exposure to asbestos and aromatic amines. RESULTS: Among CRC cases, 638 (36 %) were exposed to diesel and 814 (46 %) were exposed to gasoline emissions. Relative to the unexposed, elevated risks were observed among subjects ever exposed to high concentration levels of diesel emissions for colorectal cancer (OR = 1.65, 95 % CI = 0.98-2.80) and rectal cancer (OR = 1.98, 95 % CI = 1.09-3.60), but not colon cancer. Prolonged (>10 years) exposure at high concentrations was also associated with high risks of rectal cancer (OR = 2.33 95 % CI = 0.94-5.78; p-trend = 0.02). No statistically significant associations were observed for gasoline emissions. CONCLUSIONS: Our findings suggest that sustained high-level exposure diesel emissions may increase the risk of rectal cancer.

Environmental immune disruptors, inflammation and cancer risk.

An emerging area in environmental toxicology is the role that chemicals and chemical mixtures have on the cells of the human immune system. This is an important area of research that has been most widely pursued in relation to autoimmune diseases and allergy/asthma as opposed to cancer causation. This is despite the well-recognized role that innate and adaptive immunity play as essential factors in tumorigenesis. Here, we review the role that the innate immune cells of inflammatory responses play in tumorigenesis. Focus is placed on the molecules and pathways that have been mechanistically linked with tumor-associated inflammation. Within the context of chemically induced disturbances in immune function as co-factors in carcinogenesis, the evidence linking environmental toxicant exposures with perturbation in the balance between pro- and anti-inflammatory responses is reviewed. Reported effects of bisphenol A, atrazine, phthalates and other common toxicants on molecular and cellular targets involved in tumor-associated inflammation (e.g. cyclooxygenase/prostaglandin E2, nuclear factor kappa B, nitric oxide synthesis, cytokines and chemokines) are presented as example chemically mediated target molecule perturbations relevant to cancer. Commentary on areas of additional research including the need for innovation and integration of systems biology approaches to the study of environmental exposures and cancer causation are presented.

Occupational exposure to crystalline silica and the risk of lung cancer in Canadian men.

Crystalline silica is a recognized carcinogen, but the association with lung cancer at lower levels of exposure has not been well characterized. This study investigated the relationship between occupational silica exposure and lung cancer and the combined effects of cigarette smoking and silica exposure on lung cancer risk. A population-based case-control study was conducted in eight Canadian provinces between 1994 and 1997. Self-reported questionnaires were used to obtain a lifetime occupational history and information on other risk factors. Occupational hygienists assigned silica exposures to each job based on concentration, frequency and reliability. Data from 1681 incident lung cancer cases and 2053 controls were analyzed using logistic regression to estimate odds ratios (OR) and their 95% confidence intervals (CI). Models included adjustments for cigarette smoking, lifetime residential second-hand smoke and occupational exposure to diesel and gasoline engine emissions. Relative to the unexposed, increasing duration of silica exposure at any concentration was associated with a significant trend in lung cancer risk (OR ≥ 30 years: 1.67, 1.21-2.24; ptrend = 0.002). The highest tertile of cumulative silica exposure was associated with lung cancer (OR = 1.81, 1.34-2.42; ptrend = 0.004) relative to the lowest. Men exposed to silica for ≥30 years with ≥40 cigarette pack-years had the highest risk relative to those unexposed with <10 pack-years (OR = 42.53, 23.54-76.83). The joint relationship with smoking was consistent with a multiplicative model. Our findings suggest that occupational exposure to silica is a risk factor for lung cancer, independently from active and passive smoking, as well as from exposure to other lung carcinogens.

Residential exposure to ambient fine particulate matter (PM2.5) and nitrogen dioxide (NO2) and incident breast cancer among young women in Ontario, Canada.

BACKGROUND: Air pollution has been classified as a human carcinogen based largely on findings for respiratory cancers. Emerging, but limited, evidence suggests that it increases the risk of breast cancer, particularly among younger women. We characterized associations between residential exposure to ambient fine particulate matter (PM2.5) and nitrogen dioxide (NO2) and breast cancer. Analyses were performed using data collected in the Ontario Environmental Health Study (OEHS). METHODS: The OEHS, a population-based case-control study, identified incident cases of breast cancer in Ontario, Canada among women aged 18-45 between 2013 and 2015. A total of 465 pathologically confirmed primary breast cancer cases were identified from the Ontario Cancer Registry, while 242 population-based controls were recruited using random-digit dialing. Self-reported questionnaires were used to collect risk factor data and residential histories. Land-use regression and remote-sensing estimates of NO2 and PM2.5, respectively, were assigned to the residential addresses at interview, five years earlier, and at menarche. Logistic regression was used to estimate odds ratios (OR) and their 95 % confidence intervals (CI) in relation to an interquartile range (IQR) increase in air pollution, adjusting for possible confounders. RESULTS: PM2.5 and NO2 were positively correlated with each other (r = 0.57). An IQR increase of PM2.5 (1.9 µg/m3) and NO2 (6.6 ppb) at interview residence were associated with higher odds of breast cancer and the adjusted ORs and 95 % CIs were 1.37 (95 % CI = 0.98-1.91) and 2.33 (95 % CI = 1.53-3.53), respectively. An increased odds of breast cancer was observed with an IQR increase in NO2 at residence five years earlier (OR = 2.16, 95 % CI: 1.41-3.31), while no association was observed with PM2.5 (OR = 0.96, 95 % CI 0.64-1.42). CONCLUSIONS: Our findings support the hypothesis that exposure to ambient air pollution, especially those from traffic sources (i.e., NO2), increases the risk of breast cancer in young women.

Multiple pesticide exposures and the risk of multiple myeloma in Canadian men.

Multiple myeloma (MM) has been linked to certain agricultural exposures, including pesticides. This analysis aimed to investigate the association between lifetime use of multiple pesticides and MM risk using two exposure metrics: number of pesticides used and days per year of pesticide use. A frequency-matched, population-based case-control study was conducted among men in six Canadian provinces between 1991 and 1994. Data from 342 MM cases and 1,357 controls were analyzed using logistic regression to calculate odds ratios (OR) and 95% confidence intervals. Pesticides were grouped by type, chemical class and carcinogenic potential, using a composite carcinogenic probability score. Selected individual pesticides were also examined. Regression models were adjusted for age, province of residence, use of proxy respondents, smoking and selected medical history variables. The overall pattern of results was complex. Positive trends in risk were observed for fungicides (ptrend=0.04) and pesticides classified as probably carcinogenic or higher (ptrend=0.03). Excess risks of MM were observed among men who reported using at least one carbamate pesticide (OR=1.94, 1.16-3.25), one phenoxy herbicide (OR=1.56, 1.09-2.25) and ≥3 organochlorines (OR=2.21, 1.05-4.66). Significantly higher odds of MM were seen for exposure to carbaryl (OR=2.71, 1.47-5.00) and captan (OR=2.96, 1.40-6.24). Use of mecoprop for >2 days per year was also significantly associated with MM (OR=2.15, 1.03-4.48). Focusing on multiple pesticide exposures is important because this more accurately reflects how exposures occur in occupational settings. Significant associations observed for certain chemical classes and individual pesticides suggest that these may be MM risk factors.

Exposures to multiple pesticides and the risk of Hodgkin lymphoma in Canadian men.

PURPOSE: To determine the risk of Hodgkin lymphoma (HL) associated with exposures to multiple pesticides grouped by various classes, including carcinogenic classifications. METHODS: Data collected in the Cross-Canada Study of Pesticides and Health, a population-based incident case-control study in six provinces conducted between 1991 and 1994, were analyzed using unconditional logistic regression. Cases (n = 316) were identified through provincial cancer registries and hospital records. Controls (n = 1,506) were frequency-matched to cases by age (± 2 years) within each province and were identified through provincial health records, telephone listings, or voter lists. The Cochran-Armitage test was used to check for trends within pesticide classes. RESULTS: Overall, there was an increase in the risk of HL among all subjects who reported use of five or more insecticides (OR 1.88, 95% CI 0.92-3.87) and among subjects younger than 40 who reported use of two acetylcholinesterase inhibitors (OR 3.16, 95% CI 1.02-9.29). There was an elevated odds ratio associated with reported use of three or more probably carcinogenic pesticides (OR 2.47, 95% CI 1.06-5.75), but no increase in risk for use of possibly carcinogenic pesticides. The risk of HL from reported use of fungicides or any pesticides was greater for cases diagnosed before age 40 than for cases diagnosed at or after age 40. When analyses excluded proxy respondents, OR estimates strengthened in some circumstances. CONCLUSIONS: This study found associations between HL and fungicides, insecticides, specifically acetylcholinesterase inhibitors, and pesticides previously identified as probable human carcinogens. These associations should be further evaluated, specifically in relation to age at diagnosis.

A geospatial assessment of industrial releases and pediatric neuroblastic tumours at diagnosis: A retrospective case series.

Environmental risk factors associated with malignancy of pediatric neuroblastic tumours are not well-known and few studies have examined the relationship between industrial emissions and neuroblastic tumour diagnosis. A retrospective case series of 310 patients was evaluated at a tertiary hospital in Toronto, Canada between January 2008, and December 2018. Data from the National Pollutant Release Inventory (NPRI) were used to estimate exposure for a dozen chemicals with known or suspected carcinogenicity or embryotoxicity. Comparative analysis and predictive logistic regression models for malignant versus benign neuroblastic tumours included variables for residential proximity, number, and type of industries, mean total emissions within 2 km, and inverse distance weighted (IDW) quantity of chemical-specific industrial emissions estimated within 10 and 50 km of cases. No significant difference was seen between malignant and benign cases with respect to the mean nearest residential distance to industry, the number or type of industry, or the mean total quantity of industrial emissions within a 2 km radius of residential location of cases. However, there were statistically significant differences in the interpolated IDW emissions of dioxins and furans released between 1993 and 2019 within 10 km. Concentrations were significantly higher in malignant neuroblastic tumours at 1.65 grams (g) toxic equivalent (TEQ) (SD 2.01 g TEQ) compared to benign neuroblastic tumours at 1.13 g TEQ (SD 0.84 g TEQ) (p = 0.05). Within 50 km 3 years prior to diagnosis, malignant cases were exposed to higher levels of aluminum, benzene, and nitrogen dioxide (p = 0.02, p = 0.04, and p = 0.02 respectively). Regression analysis of the IDW emissions within a 50 km radius revealed higher odds of exposure to benzene for malignant neuroblastic tumours (OR = 1.03, CI: 1.01-1.05, p = 0.01). These preliminary findings suggest a potential role of industrial emissions in the development of malignant pediatric neuroblastic tumours and underscore the need for further research to investigate these associations.

Pesticide use, immunologic conditions, and risk of non-Hodgkin lymphoma in Canadian men in six provinces.

Pesticide exposures and immune suppression have been independently associated with the risk of non-Hodgkin lymphoma (NHL), but their joint effect has not been well explored. Data from a case-control study of men from six Canadian provinces were used to evaluate the potential effect modification of asthma, allergies, or asthma and allergies and hay fever combined on NHL risk from use of: (i) any pesticide; (ii) any organochlorine insecticide; (iii) any organophosphate insecticide; (iv) any phenoxy herbicide; (v) selected individual pesticides [1,1'-(2,2,2-trichloroethylidene)bis[4-chlorobenzene]; 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT), malathion, (4-chloro-2-methylphenoxy)acetic acid (MCPA), mecoprop, and (2,4-dichlorophenoxy)acetic acid (2,4-D); and (vi) from the number of potentially carcinogenic pesticides. Incident NHL cases (n = 513) diagnosed between 1991 and 1994 were recruited from provincial cancer registries and hospitalization records and compared to 1,506 controls. A stratified analysis was conducted to calculate odds ratios (ORs) adjusted for age, province, proxy respondent, and diesel oil exposure. Subjects with asthma, allergies, or hay fever had non-significantly elevated risks of NHL associated with use of MCPA (OR = 2.67, 95% confidence interval [CI]: 0.90-7.93) compared to subjects without any of these conditions (OR = 0.81, 95% CI: 0.39-1.70). Conversely, those with asthma, allergies, or hay fever who reported use of malathion had lower risks of NHL (OR = 1.25, 95% CI: 0.69-2.26) versus subjects with none of these conditions (OR = 2.44, 95% CI: 1.65-3.61). Similar effects were observed for asthma and allergies evaluated individually. Although there were some leads regarding effect modification by these immunologic conditions on the association between pesticide use and NHL, small numbers, measurement error and possible recall bias limit interpretation of these results.

Occupational exposure to asbestos and lung cancer in men: evidence from a population-based case-control study in eight Canadian provinces.

BACKGROUND: Asbestos is classified as a human carcinogen, and studies have consistently demonstrated that workplace exposure to it increases the risk of developing lung cancer. Few studies have evaluated risks in population-based settings where there is a greater variety in the types of occupations, and exposures. METHODS: This was a population based case-control study with 1,681 incident cases of lung cancer, and 2,053 controls recruited from 8 Canadian provinces between 1994 and 1997. Self-reported questionnaires were used to elicit a lifetime occupational history, including general tasks, and information for other risk factors. Occupational hygienists, who were blinded to case-control status, assigned asbestos exposures to each job on the basis of (i) concentration (low, medium, high), (ii) frequency (<5%, 5-30%, and >30% of the time in a normal work week), and (iii) reliability (possible, probable, definite). Logistic regression was used to estimate odds ratios (ORs) and their corresponding 95% confidence intervals (CI). RESULTS: Those occupationally exposed to (i) low, and (ii) medium or high concentrations of asbestos had ORs for lung cancer of 1.17 (95% CI=0.92 - 1.50) and 2.16 (95% CI=1.21-3.88), respectively, relative to those who were unexposed. Medium or high exposure to asbestos roughly doubled the risk for lung cancer across all three smoking pack-year categories. The joint relationship between smoking and asbestos was consistent with a multiplicative risk model. CONCLUSIONS: Our findings provide further evidence that exposure to asbestos has contributed to an increased risk of lung cancer in Canadian workplaces, and suggests that nearly 3% of lung cancers among Canadian men are caused by occupational exposure to asbestos.

Intake of phytoestrogen foods and supplements among women recently diagnosed with breast cancer in Ontario, Canada.

Phytoestrogens are found in foods such as soy (isoflavones) and flaxseed (lignans), and certain botanical supplements. Their role in estrogen receptor positive (ER+) breast cancer recurrence and treatment is controversial, and it is unknown how this affects intake among patients. The Ontario Cancer Registry was used to identify 417 population-based breast cancer cases (mean time from diagnosis was 57 days). A questionnaire was mailed to determine intake of phytoestrogen foods and supplements in the last 2 mo, changes since diagnosis and differences by ER tumor status or hormonal treatment. Of 278 (67%) respondents, 56% consumed soy foods, 39% consumed isoflavone-rich foods (tofu, soybeans, soy milk, soy nuts), and 70% ate lignan-rich foods, including flaxseed (33%). Only soy milk, flaxseed, and flaxseed bread were commonly consumed more than once/wk. Few patients (4%) took isoflavone (soy, red clover, kudzu, licorice, isoflavones) or lignan/flaxseed supplements. Since diagnosis, 17% started or stopped soy foods (most stopped); this was more prevalent among those receiving hormonal treatment (20%; 95% confidence interval (CI): 14, 26) than not (6%; 95% CI: 1, 12). No other differences by ER status or hormonal treatment were observed. Research is needed to confirm this and to explore influencing factors.

Challenges associated with quantification of selected urinary biomarkers of exposure to tobacco products.

Tobacco use, of which cigarette smoking is the most common, is a global health concern and is directly linked to over 7 million premature deaths annually. Measurement of the levels of tobacco-related biomarkers in biological matrices reflects human exposure to the chemicals in tobacco products. Nicotine, nicotine metabolites, anatabine, and anabasine are specific to tobacco and nicotine containing products. However, as nicotine and its metabolites are ubiquitous in the environment, background contamination during sample preparation can occur, making the quantification of target analytes challenging. The main purpose of the present study was to examine quality control measures needed in the determination of urinary nicotine, nicotine metabolites, anatabine, and anabasine. Urine samples (n = 75) and NIST standard reference materials SRM 3671 and SRM 3672 were analysed. A one-step extraction procedure using cold acetone was used in this study, which involved no additional clean up. The blank matrices investigated included synthetic urine prepared with HPLC-grade water, synthetic urine prepared with Milli-Q water, and bovine urine. By adopting strategies for minimizing the background levels, very low detection limits for all the target analytes ranging from 0.025 ng/mL for 3-hydroxycotinine to 0.634 ng/mL for nicotine, were achieved. Recoveries ranged between 67% and 118% with RSD values below 20%. Intra-day and inter-day precisions were in the range of 1.1-11.7% and 4.8-25.2%, respectively. The levels of all target analytes were higher in daily smokers than in non-smokers, with the largest difference observed for 3-hydroxycotinine. No difference was observed in the levels of target analytes between individuals who were former smokers, who never smoked or who were exposed to environmental tobacco smoke (ETS), except for total nicotine equivalents (TNE), which was significantly higher in non-smokers exposed to environmental tobacco smoke compared with study participants who never smoked. The results obtained from SRM 3671 and SRM 3672 could inform a potential certification of additional biomarkers of exposure to tobacco products in those standard reference materials.

A Selective and Sensitive Gas Chromatography-Tandem Mass Spectrometry Method for Quantitation of Synthetic Musks in Human Serum.

BACKGROUND: Synthetic musk compounds are widely used as fragrances in many consumer products; however, information on human exposure and health effects is limited. Also, analytical methods for their quantification in biological matrices are limited. OBJECTIVE: In this study, an integrated method was developed and validated for the analysis of selected synthetic musk compounds in human serum. METHOD: The method is based on liquid-liquid extraction (LLE), sample clean-up by solid-phase extraction (SPE), and separation and detection by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). RESULTS: The method demonstrated good recoveries (86-105%) and high sensitivity, with low method detection limits (MDLs) ranging from 0.04 to 0.17 µg/L. The method was applied to the analysis of 10 synthetic musk compounds in 40 serum samples collected from Canadian women aged 20-44 years (20 individual samples collected in 2014 and 20 pooled samples collected in 2006). The most commonly detected compound was Galaxolide (HHCB), with median concentrations of 0.59 µg/L in samples collected in 2006, and 0.34 µg/L for samples collected in 2014. Musk ketone (MK) was not detected in any of the samples collected in 2006, but was detected in 60% of the samples collected in 2014 with a median concentration of 0.29 µg/L. Tonalide (AHTN) was detected in only one sample above its MDL (0.12 µg/L). CONCLUSIONS: This is the first study in Canada to report levels of synthetic musks in human. The data generated from this study has been used in risk screening assessment by Environment and Climate Change Canada and Health Canada.