Urinary biomonitoring of glyphosate exposure among male farmers and nonfarmers in the Biomarkers of Exposure and Effect in Agriculture (BEEA) study

Glyphosate is the most widely applied herbicide worldwide. Glyphosate biomonitoring data are limited for agricultural settings. We measured urinary glyphosate concentrations and assessed exposure determinants in the Biomarkers of Exposure and Effect in Agriculture (BEEA) study. We selected four groups of BEEA participants based on self-reported pesticide exposure: recently exposed farmers with occupational glyphosate use in the last 7 days (n = 98), farmers with high lifetime glyphosate use (>80th percentile) but no use in the last 7 days (n = 70), farming controls with minimal lifetime use (n = 100), and nonfarming controls with no occupational pesticide exposures and no recent home/garden glyphosate use (n = 100). Glyphosate was quantified in first morning void urine using ion chromatography isotope-dilution tandem mass spectrometry. We estimated associations between urinary glyphosate concentrations and potential determinants using multivariable linear regression. Glyphosate was detected (≥0.2 µg/L) in urine of most farmers with recent (91 %) and high lifetime (93 %) use, as well as farming (88 %) and nonfarming (81 %) controls; geometric mean concentrations were 0.89, 0.59, 0.46, and 0.39 µg/L (0.79, 0.51, 0.42, and 0.37 µg/g creatinine), respectively. Compared with both control groups, urinary glyphosate concentrations were significantly elevated among recently exposed farmers (P < 0.0001), particularly those who used glyphosate in the previous day [vs. nonfarming controls; geometric mean ratio (GMR) = 5.46; 95 % confidence interval (CI): 3.75, 7.93]. Concentrations among high lifetime exposed farmers were also elevated (P < 0.01 vs. nonfarming controls). Among recently exposed farmers, glyphosate concentrations were higher among those not wearing gloves when applying glyphosate (GMR = 1.91; 95 % CI: 1.17, 3.11), not wearing long-sleeved shirts when mixing/loading glyphosate (GMR = 2.00; 95 % CI: 1.04, 3.86), applying glyphosate exclusively using broadcast/boom sprayers (vs. hand sprayer only; GMR = 1.70; 95 % CI: 1.00, 2.92), and applying glyphosate to crops (vs. non-crop; GMR = 1.72; 95 % CI: 1.04, 2.84). Both farmers and nonfarmers are exposed to glyphosate, with recency of occupational glyphosate use being the strongest determinant of urinary glyphosate concentrations. Continued biomonitoring of glyphosate in various settings is warranted.

Exposure to Per- and Polyfluoroalkyl Substances and Breast Cancer Risk: A Systematic Review and Meta-analysis of Epidemiologic Studies

We synthesized the epidemiologic evidence on the associations between per- and polyfluoroalkyl substances (PFAS) exposure and breast cancer risk. Our systematic review and meta-analysis included 18 and 11 articles, respectively, covering studies up to February 2023. The summary relative risks (RR) estimated by random-effects meta-analyses did not support an association between PFAS and overall breast cancer risk (e.g., a natural log (ln)-unit increase in serum/plasma concentrations [ng/mL] for perfluorooctanoate [PFOA] RR=0.95, 95% confidence interval [CI]:0.77-1.18; perfluorooctane sulfonate [PFOS] RR=0.98, 95%CI: 0.87-1.11). However, when limiting to studies that assessed exposures prior to a breast cancer diagnosis, we observed a positive association with PFOA (a ln-unit increase, RR=1.16, 95%CI: 0.96-1.40). We also observed some possible heterogeneous associations by tumor estrogen and progesterone receptor status among postmenopausal breast cancer cases. No meaningful changes were observed after excluding the studies with high risk-of-bias (Tier 3). Based on the evaluation tool developed by the National Toxicology Program, given the heterogeneity across studies and the variability in timing of exposure measurements, the epidemiologic evidence needed to determine the association between PFAS exposure and breast cancer remains inadequate. Our findings support the need for future studies with improved study designs to determine this association.

Glyphosate Use and Mosaic Loss of Chromosome Y among Male Farmers in the Agricultural Health Study

BACKGROUND

Glyphosate is the most commonly used herbicide worldwide and has been implicated in the development of certain hematologic cancers. Although mechanistic studies in human cells and animals support the genotoxic effects of glyphosate, evidence in human populations is scarce.

OBJECTIVES

We evaluated the association between lifetime occupational glyphosate use and mosaic loss of chromosome Y (mLOY) as a marker of genotoxicity among male farmers.

METHODS

We analyzed blood-derived DNA from 1,606 farmers ≥ 50 years of age in the Biomarkers of Exposure and Effect in Agriculture study, a subcohort of the Agricultural Health Study. mLOY was detected using genotyping array intensity data in the pseudoautosomal region of the sex chromosomes. Cumulative lifetime glyphosate use was assessed using self-reported pesticide exposure histories. Using multivariable logistic regression, we estimated odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between glyphosate use and any detectable mLOY (overall mLOY) or mLOY affecting ≥ 10 % of cells (expanded mLOY).

RESULTS

Overall, mLOY was detected in 21.4% of farmers, and 9.8% of all farmers had expanded mLOY. Increasing total lifetime days of glyphosate use was associated with expanded mLOY [highest vs. lowest quartile; OR = 1.75 (95% CI: 1.00, 3.07), p trend = 0.03 ] but not with overall mLOY; the associations with expanded mLOY were most apparent among older (≥ 70 years of age) men [OR = 2.30 (95% CI: 1.13, 4.67), p trend = 0.01 ], never smokers [OR = 2.32 (95% CI: 1.04, 5.21), p trend = 0.04 ], and nonobese men [OR = 2.04 (95% CI: 0.99, 4.19), p trend = 0.03 ]. Similar patterns of associations were observed for intensity-weighted lifetime days of glyphosate use.

DISCUSSION

High lifetime glyphosate use could be associated with mLOY affecting a larger fraction of cells, suggesting glyphosate could confer genotoxic or selective effects relevant for clonal expansion. As the first study to investigate this association, our findings contribute novel evidence regarding the carcinogenic potential of glyphosate and require replication in future studies. https://doi.org/10.1289/EHP12834.

Serum concentrations of per- and polyfluoroalkyl substances and risk of renal cell carcinoma in the Multiethnic Cohort Study

Per- and polyfluoroalkyl substances (PFAS) are environmentally persistent organic pollutants detectable in the serum of most U.S. adults. We previously reported a positive association between serum perfluorooctanoate (PFOA) concentrations and risk of renal cell carcinoma (RCC) within the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, comprising predominantly White individuals enrolled in 1993-2001. To extend our investigations to a larger and more racially and ethnically diverse population, we conducted a nested case-control study of serum PFAS concentrations and RCC within the Multiethnic Cohort Study. We measured pre-diagnostic serum concentrations of nine PFAS among 428 RCC cases and 428 individually matched controls. We estimated odds ratios (ORs) and 95 % confidence intervals (CIs) for risk of RCC in relation to each PFAS using conditional logistic regression, adjusting for RCC risk factors and other PFAS. PFOA was not associated with RCC risk overall [doubling in serum concentration, ORcontinuous = 0.89 (95 %CI = 0.67, 1.18)]. However, we observed suggestive positive associations among White participants [2.12 (0.87, 5.18)] and among participants who had blood drawn before 2002 [1.49 (0.77, 2.87)]. Furthermore, higher perfluorononanoate (PFNA) concentration was associated with increased risk of RCC overall [fourth vs. first quartile, OR = 1.84 (0.97, 3.50), Ptrend = 0.04; ORcontinuous = 1.29 (0.97, 1.71)], with the strongest association observed among African American participants [ORcontinuous = 3.69 (1.33, 10.25)], followed by Native Hawaiian [2.24 (0.70, 7.19)] and White [1.98 (0.92, 4.25)] participants. Most other PFAS were not associated with RCC. While PFOA was not associated with RCC risk overall in this racially and ethnically diverse population, the positive associations observed among White participants and those with sera collected before 2002 are consistent with previous PLCO findings. Our study also provided new evidence of a positive association between PFNA and RCC risk that was strongest in African American participants. These findings highlight the need for additional epidemiologic research investigating PFAS exposures and RCC in large racially and ethnically diverse populations.

Abstract 4220: Occupational pesticide use and relative leukocyte telomere length in the biomarkers of exposure and effect in agriculture study

Background: Previous epidemiologic studies have reported increased risks of certain cancers in relation to specific pesticide exposures, although the mechanisms underlying many of these associations remain poorly understood. Within the Biomarkers of Exposure and Effect in Agriculture (BEEA) study, a molecular epidemiologic investigation of pesticide applicators in Iowa and North Carolina, we examined whether occupational use of pesticides is associated with alterations in leukocyte telomere length. Telomeres are essential in maintaining chromosomal stability and altered telomere length has been linked to various malignancies.

Methods: Relative telomere length (RTL) was measured using quantitative PCR in leukocytes from 1,539 male pesticide applicators ≥50 years of age. Using self-reported information on pesticide use, we characterized lifetime use of specific pesticides in terms of ever use and intensity-weighted lifetime days (IWLDs), a metric integrating total lifetime days of use and other factors influencing exposure. Multivariable linear regression models were used to estimate differences in geometric mean RTL (and corresponding 95% confidence intervals) by ever vs. never use of 48 pesticides and in exposure-response analyses for IWLDs of use of 46 pesticides, adjusting for age, state of residence, race/ethnicity, body mass index, and cigarette smoking status and pack-years.

Results: Among ever users of the insecticides lindane and aldicarb, mean RTL was significantly longer compared to never users (p=0.01 and 0.03, respectively); in exposure-response analyses, we also observed a suggestive but non-statistically significant trend between increasing IWLDs of lindane use and longer RTL (p-trend=0.07). Higher IWLDs of use of the insecticide diazinon was also associated with longer RTL (p-trend=0.03) while increasing IWLDs of the insecticide heptachlor and the herbicide 2,4,5-TP were associated with shorter RTL (p-trends=0.04 and 0.03, respectively).

Conclusions: This is, to our knowledge, the largest investigation of occupational pesticide use and RTL to date. Our findings provide novel evidence suggesting that use of certain pesticides could be associated with altered leukocyte telomere length. Notably, diazinon and lindane have previously been associated with increased risks of lung and lymphoid malignancies, respectively, and longer leukocyte telomere length has been implicated in the development of these cancers.

Citation Format: Patricia A. Erickson, Vicky C. Chang, Casey L. Dagnall, Kedest Teshome, Mitchell J. Machiela, Kathryn H. Barry, Shahinaz M. Gadalla, Laura E. Beane Freeman, Gabriella Andreotti, Jonathan N. Hofmann. Occupational pesticide use and relative leukocyte telomere length in the biomarkers of exposure and effect in agriculture study. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4220.

Iron Status and Associated Factors among Canadian Women: Results from the Canadian Health Measures Survey

BACKGROUND

Iron deficiency and overload may negatively impact women's health. There has been limited assessment of iron status and its associated factors among Canadian women.

OBJECTIVES

This study investigated associations of various sociodemographic, lifestyle, medication, and dietary factors with body iron stores among pre- and postmenopausal women in Canada.

METHODS

Analyses were conducted using cross-sectional, nationally representative survey and biomarker data from women aged 20-79 y (n = 6362) in the Canadian Health Measures Survey (2009-2017). Body iron stores were assessed by measuring serum concentrations of ferritin (SF). Information on potential correlates was collected during an in-home interview. Multivariable linear regression analyses were performed to evaluate associations with SF concentration, and logistic regression was used to estimate associations with iron deficiency (SF <15 μg/L) or elevated iron stores (SF >150 μg/L).

RESULTS

Geometric mean SF concentrations were significantly higher in postmenopausal than in premenopausal women (73.2 versus 33.8 μg/L; P < 0.001). The prevalence of iron deficiency among pre- and postmenopausal women was 16.0% and 4.0%, respectively, whereas that of elevated iron stores was 2.7% and 21.0%, respectively. After simultaneous adjustment for multiple factors, including high-sensitivity CRP (inflammation marker), we found that age, East/Southeast Asian (versus White) race/ethnicity, alcohol, and red meat consumption were positively associated with SF concentration among pre- and postmenopausal women. In addition, aspirin use and dairy consumption were inversely associated with SF concentration among postmenopausal women only. Similar patterns were observed for associations with elevated iron stores among postmenopausal women, whereas higher grain consumption was associated with an increased prevalence of iron deficiency among premenopausal women.

CONCLUSIONS

Sociodemographic, lifestyle, medication, and dietary factors are correlated with iron status determined by SF concentration among Canadian women. The findings may have implications for intervention strategies aimed at optimizing body iron stores in pre- and postmenopausal women.

Serum perfluorooctane sulfonate and perfluorooctanoate and risk of postmenopausal breast cancer according to hormone receptor status: An analysis in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial

Per- and polyfluoroalkyl substances (PFAS) are highly persistent endocrine-disrupting chemicals that may contribute to breast cancer development; however, epidemiologic evidence is limited. We investigated associations between prediagnostic serum levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) and postmenopausal breast cancer risk, overall and by hormone receptor status, in a nested case-control study of 621 cases and 621 matched controls in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. PFOS and PFOA levels were determined based on serum metabolomic profiling performed using ultraperformance liquid chromatography-tandem mass spectrometry. We used multivariable conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between each PFAS and breast cancer risk, overall, by estrogen receptor (ER) or progesterone receptor (PR) status, and by joint ER/PR status. We found little evidence of association between PFOS or PFOA and breast cancer risk overall. However, in subtype-specific analyses, we observed statistically significant increased risks of ER+, PR+, and ER+/PR+ tumors for the third vs lowest quartile of serum PFOS (ORs [95% CIs] = 1.59 [1.01-2.50], 2.34 [1.29-4.23], and 2.19 [1.21-3.98], respectively) and elevated but nonstatistically significant ORs for the fourth quartile. Conversely, for PFOA, modest positive associations with ER-, PR-, ER+/PR-, and ER-/PR- tumors were generally seen in the upper quartiles. Our findings contribute evidence supporting positive associations between serum PFOS and hormone receptor-positive tumors, and possibly between PFOA and receptor-negative tumors. Future prospective studies incorporating tumor hormone receptor status are needed to better understand the role of PFAS in breast cancer etiology.

Glyphosate Exposure and Urinary Oxidative Stress Biomarkers in the Agricultural Health Study

BACKGROUND

Glyphosate is the most widely applied herbicide worldwide, and its use has been associated with increased risks of certain hematopoietic cancers in epidemiologic studies. Animal and in vitro experiments suggest that glyphosate may induce oxidative stress, a key characteristic of carcinogens; however, evidence in human populations remains scarce. We investigated associations between glyphosate exposure and urinary oxidative stress biomarkers in the Biomarkers of Exposure and Effect in Agriculture study, a molecular epidemiologic subcohort in the Agricultural Health Study.

METHODS

This analysis included 268 male farmers selected based on self-reported recent and lifetime occupational glyphosate use and 100 age- and geography-matched male non-farmers. Concentrations of glyphosate and oxidative stress biomarkers (8-hydroxy-2'-deoxyguanosine [8-OHdG], 8-iso-prostaglandin-F2α [8-isoprostane], and malondialdehyde [MDA]) were quantified in first-morning-void urine. We performed multivariable linear regression to evaluate associations of urinary glyphosate and self-reported glyphosate use with each oxidative stress biomarker.

RESULTS

Urinary glyphosate concentrations were positively associated with levels of 8-OHdG (highest vs. lowest glyphosate quartile; geometric mean ratio [GMR]=1.15, 95% confidence interval [CI]=1.03-1.28, Ptrend=.02) and MDA (GMR = 1.20, 95% CI = 1.03-1.40, Ptrend=.06) overall. Among farmers reporting recent glyphosate use (last 7 days), use in the previous day was also associated with significantly increased 8-OHdG and MDA levels. Compared with non-farmers, we observed elevated 8-isoprostane levels among farmers with recent, high past 12-month, or high lifetime glyphosate use.

CONCLUSIONS

Our findings contribute to the weight of evidence supporting an association between glyphosate exposure and oxidative stress in humans and may inform evaluations of the carcinogenic potential of this herbicide.

Abstract 5895: Examining the association between arsenic exposure and cancer risk among Canadian adults

Background: Arsenic is a highly prevalent environmental toxin and an established carcinogen for cancers of the skin, bladder, and lung. Emerging evidence also suggests that arsenic exposure may be a risk factor for breast and other cancers. Previous studies have been conducted in populations with endemically high levels of arsenic; however, the impact of chronic exposure to low levels is not known. Thus, the purpose of this study was to describe the arsenic exposure in Canadian adults and to evaluate the association between arsenic status and cancer risk.

Methods: The Canadian Health Measures Survey (CHMS) is an ongoing, nationally representative survey that collects self-reported and objective health measures, including biomonitoring data, from participants in biennial cycles. This analysis utilized total, inorganic and organic urinary arsenic biomarkers (µg/L) from Cycles 1-5 (2007-2017) of the CHMS. Incident cancers were ascertained through a linkage to the Canadian Cancer Registry. Arsenic exposure was described using weighted percentiles, and Cox proportional hazards regression models were used to estimate the association between arsenic exposure and cancer risk (overall and site-specific).

Results: This analysis included 10,000 individuals, aged 18-80. The median total urinary arsenic level was 7.5 ug/g of creatinine. Preliminary models showed that levels of inorganic arsenic exposure above the geometric mean (&gt; 4.5 µg/L) were associated with a 3-fold increased risk of developing any cancer (HR = 3.58; 95%CI 1.63-7.85), compared to those with lower levels. Site-specific risk modelling is ongoing and preliminary results will be presented.

Significance: This study found inorganic arsenic exposure may be associated with an increased risk of developing cancer. To our knowledge, this study is the first to ascertain national estimates of arsenic exposure and provide insight on the relationship between arsenic exposure and cancer risk in Canadian adults. These findings are critical for developing population-level interventions to reduce the Canadian, and global, cancer burden.

Citation Format: Katherine Pullella, Vicky C. Chang, Shelley A. Harris, Anthony J. Hanley, John R. McLaughlin, Jan Lubinski, Steven A. Narod, Joanne Kotsopoulos. Examining the association between arsenic exposure and cancer risk among Canadian adults [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5895.

Risk factors for early-onset colorectal cancer: a population-based case-control study in Ontario, Canada

Purpose

There has been an alarming increase in colorectal cancer (CRC) incidence among young adults aged < 50 years, and factors driving this upward trend are unknown. This study investigated associations between various medical, lifestyle, and dietary factors and risk of early-onset CRC (EO-CRC).

Methods

A population-based case–control study was conducted in Ontario, Canada during 2018–2019. EO-CRC cases aged 20–49 years (n = 175) were identified from the Ontario Cancer Registry; sex- and age group-matched controls (n = 253) were recruited through random digit dialing. Data on potential a priori risk factors were collected using a web-based self-reported questionnaire. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using multivariable logistic regression.

Results

Family history of CRC in a first- or second-degree relative (OR 2.37; 95% CI 1.47–3.84), longer sedentary time (≥ 10 vs. < 5 h/day, OR 1.93; 95% CI 1.02–3.65), greater consumption of sugary drinks (≥ 7 vs. < 1 drinks/week, OR 2.99; 95% CI 1.57–5.68), and a more Westernized dietary pattern (quartile 4 vs. 1, OR 1.92; 95% CI 1.01–3.66) were each associated with an increased risk of EO-CRC. Conversely, calcium supplement use (OR 0.53; 95% CI 0.31–0.92), history of allergy or asthma (OR 0.62; 95% CI 0.39–0.98), and greater parity in females (≥ 3 vs. nulliparity, OR 0.29; 95% CI 0.11–0.76) were each associated with a reduced risk.

Conclusion

Modifiable factors, particularly sedentary behavior and unhealthy diet including sugary drink consumption, may be associated with EO-CRC risk. Our findings, if replicated, may help inform prevention strategies targeted at younger persons.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10552-021-01456-8.

Surveillance of concussion-related injuries using electronic medical records from the Canadian Primary Care Sentinel Surveillance Network (CPCSSN): a proof-of-concept

INTRODUCTION

Previous studies on traumatic brain injury trends in Canada have been restricted to hospitalization and emergency department visit data. However, many concussion patients may present first, or only, to family physicians. Therefore, the true burden of concussion in Canada is likely underestimated. The Canadian Primary Care Sentinel Surveillance Network (CPCSSN) collects information electronically from family physicians across Canada and can potentially be used for concussion surveillance. The objective of this study is to explore the feasibility of using data collated from CPCSSN for concussion surveillance purposes and examine trends over time.

METHODS

Electronic medical records housed by CPCSSN from 2010 to 2016 were analyzed. Case ascertainment was determined through a combination of International Classification of Diseases, Ninth Revision codes. Binomial regression models were used to calculate the prevalence ratio (PR) of concussion by age, sex, deprivation indices, body mass index, and comorbid conditions.

RESULTS

Concussion prevalence rates increased from 2010 to 2016 (p < 0.001). Based on 2016 data, males had a higher prevalence of concussion compared with females (PR = 1.09; 95% CI 1.02, 1.18), and those aged 10-14 (PR = 8.52; 95% confidence interval [CI] 6.34, 11.44) and 15-19 (PR = 7.75; 95% CI 5.84, 10.28) had higher prevalence of concussion compared with those aged 0-4 years.

CONCLUSION

This pilot study demonstrates the feasibility of using the CPCSSN system for surveillance of concussion in the Canadian population. The initial findings on prevalence are in agreement with previous studies that have used hospitalization or emergency department data.

Abstract 623: Iron intake, oxidative stress-related genes, and breast cancer risk

Background: Iron has been shown to enhance breast carcinogenesis in animal models through generation of oxidative stress, although epidemiological evidence of the association between iron intake and breast cancer risk remains inconclusive. This study investigated associations between different types of iron intake and breast cancer risk, and whether these associations were modified by genetic polymorphisms in antioxidant enzymes, including manganese superoxide dismutase (MnSOD) and glutathione S-transferases M1 (GSTM1) and T1 (GSTT1).

Methods: A population-based case-control study in Ontario, Canada recruited 3,030 breast cancer cases identified from the Ontario Cancer Registry and 3,402 controls from random digit dialing. Iron intake from foods and supplements was assessed using a 178-item food frequency questionnaire. Multivariable logistic regression analyses were used to evaluate associations between breast cancer risk and intakes of dietary, supplemental, and total (dietary plus supplemental) iron, among all women and stratified by menopausal status. Associations were also examined by hormone receptor [estrogen receptor (ER)/progesterone receptor (PR)] tumor subtype. Among women providing saliva (DNA) samples (1,696 cases and 1,761 controls), interactions between iron intake and genetic polymorphisms were assessed using the likelihood ratio test.

Results: Among all women, intakes of dietary, supplemental, and total iron were not associated with breast cancer risk, overall or by tumor subtype. Among premenopausal women, there was an increase in breast cancer risk for the ER–PR– subtype associated with higher intakes (highest vs. lowest quintile) of dietary [odds ratio (OR) = 1.4; 95% confidence interval (CI): 0.9–2.4] and total (OR = 1.8; 95% CI: 1.1–2.9) iron (P for trend &lt; 0.05). Among postmenopausal women, supplemental iron intake (&gt;18 vs. 0 mg/day) was associated with reduced breast cancer risk (OR = 0.7; 95% CI: 0.5–0.9), with similar associations across tumor subtypes. Associations of dietary and total iron intake with overall breast cancer risk were modified by GSTT1 and/or GSTM1/T1 combined genotypes (P for interaction &lt; 0.05). For example, among women with deletions in both GSTM1 and GSTT1 loci, higher dietary iron intake was associated with increased breast cancer risk (OR = 2.1; 95% CI: 1.1–4.2), whereas null or inverse associations were found among women with other GSTM1/T1 genotypes.

Conclusions: Results from this study suggest that higher dietary and total iron intake may be associated with increased risk of ER–PR– breast cancer among premenopausal women, whereas higher supplemental iron intake may be associated with reduced postmenopausal breast cancer risk. In addition, associations between iron intake and breast cancer risk may be modified by polymorphisms in oxidative stress-related genes. Our ongoing work will investigate heme and non-heme iron intake in relation to breast cancer risk.

Citation Format: Vicky C. Chang, Michelle Cotterchio, Susan J. Bondy, Joanne Kotsopoulos. Iron intake, oxidative stress-related genes, and breast cancer risk [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 623.

Iron intake, body iron status, and risk of breast cancer: a systematic review and meta-analysis

BACKGROUND

Iron has been shown to promote breast carcinogenesis in animal models through generation of oxidative stress and interaction with estrogen. Heme iron, which is found exclusively in animal-sourced foods, is suggested to have a more detrimental effect. Epidemiological evidence of the association between iron and breast cancer risk remains inconclusive and has not been comprehensively summarized. This systematic review and meta-analysis evaluated associations between both iron intake and body iron status and breast cancer risk.

METHODS

Four electronic databases (MEDLINE, EMBASE, CINAHL, and Scopus) were searched up to December 2018 for studies assessing iron intake and/or biomarkers of iron status in relation to breast cancer risk. Using random-effects meta-analyses, pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated comparing the highest vs. lowest category of each iron measure. Dose-response meta-analyses were also performed to investigate linear and nonlinear associations.

RESULTS

A total of 27 studies were included in the review, of which 23 were eligible for meta-analysis of one or more iron intake/status measures. Comparing the highest vs. lowest category, heme iron intake was significantly associated with increased breast cancer risk, with a pooled RR of 1.12 (95% CI: 1.04-1.22), whereas no associations were found for dietary (1.01, 95% CI: 0.89-1.15), supplemental (1.02, 95% CI: 0.91-1.13), or total (0.97, 95% CI: 0.82-1.14) iron intake. Associations of iron status indicators with breast cancer risk were generally in the positive direction; however, a significant pooled RR was found only for serum/plasma levels (highest vs. lowest) of iron (1.22, 95% CI: 1.01-1.47), but not for ferritin (1.13, 95% CI: 0.78-1.62), transferrin saturation (1.16, 95% CI: 0.91-1.47), or total iron-binding capacity (1.10, 95% CI: 0.97-1.25). In addition, a nonlinear dose-response was observed for heme iron intake and serum iron (both P_nonlinearity < 0.05).

CONCLUSIONS

Heme iron intake and serum iron levels may be positively associated with breast cancer risk. Although associations were modest, these findings may have public health implications given the widespread consumption of (heme) iron-rich foods. In light of methodological and research gaps identified, further research is warranted to better elucidate the relationship between iron and breast cancer risk.

Sentinel surveillance of suspected opioid-related poisonings and injuries: trends and context derived from the electronic Canadian Hospitals Injury Reporting and Prevention Program, March 2011 to June 2017

INTRODUCTION

The opioid epidemic is currently a major public health problem in Canada. As such, knowledge of upstream risk factors associated with opioid use is needed to inform injury prevention, health promotion and harm reduction efforts.

METHODS

We analyzed data extracted from 11 pediatric and 6 general hospital emergency departments (EDs) as part of the electronic Canadian Hospitals Injury Reporting and Prevention Program (eCHIRPP) from March 2011 to June 2017. We identified suspected opioid-related injuries using search strings and manually verified them. We computed age-adjusted and sex-stratified proportionate injury ratios (PIRs) and 95% confidence intervals (CIs) to compare opioid-related injuries to all injuries in eCHIRPP. Negative binomial regression was used to determine trends over time. We conducted qualitative analyses of narratives to identify common themes across life stages.

RESULTS

Between March 2011 and June 2017, 583 suspected opioid-related poisoning/ injury cases were identified from eCHIRPP. Most of the cases were females (55%). Many of the injuries occurred in patients' own homes (51%). Forty-five percent of the injuries were intentional self-harm. Among children (aged 1-9 years), most injuries were caused by inadvertent consumption of opioids left unattended. Among youth (aged 10-19 years) and adults (aged 20-49 years), opioid use was associated with underlying mental illness. Overall, the average annual percent change (AAPC) in the rate of injuries (per 100 000 eCHIRPP cases) has been increasing since 2012 (AAPC = 11.9%, p < .05). The increase is particularly evident for males (AAPC = 16.3%, p < .05). Compared to other injuries, people with suspected opioid-related injuries were more likely to be admitted to hospital (PIR = 5.3, 95% CI: 4.6-6.2).

CONCLUSION

The upstream determinants of opioid-related injuries are complex and likely vary by subpopulations. Therefore, continued monitoring of risk factors is important in providing the evidence necessary to prevent future overdoses and deaths.

Factors associated with sleep duration across life stages: results from the Canadian Health Measures Survey

INTRODUCTION

Sleep is essential for both physical and mental well-being. This study investigated sociodemographic, lifestyle/behavioural, environmental, psychosocial and health factors associated with sleep duration among Canadians at different life stages.

METHODS

We analyzed nationally representative data from 12 174 Canadians aged 3-79 years in the Canadian Health Measures Survey (2009-2013). Respondents were grouped into five life stages by age in years: preschoolers (3-4), children (5-13), youth (14-17), adults (18-64) and older adults (65-79). Sleep duration was classified into three categories (recommended, short and long) according to established guidelines. Logistic regression models were used to identify life stage-specific correlates of short and long sleep.

RESULTS

The proportion of Canadians getting the recommended amount of sleep decreased with age, from 81% of preschoolers to 53% of older adults. Statistically significant factors associated with short sleep included being non-White and having low household income among preschoolers; being non-White and living in a lone-parent household among children; and second-hand smoke exposure among youth. Boys with a learning disability or an attention-deficit/hyperactivity disorder and sedentary male youth had significantly higher odds of short sleep. Among adults and older adults, both chronic stress and arthritis were associated with short sleep. Conversely, mood disorder and poor/fair self-perceived general health in adults and weak sense of community belonging in adults and older men were associated with long sleep.

CONCLUSION

Our population-based study identified a wide range of factors associated with short and long sleep at different life stages. This may have implications for interventions aimed at promoting healthy sleep duration.

Effect of Dietary Flaxseed Intake on Circulating Sex Hormone Levels among Postmenopausal Women: A Randomized Controlled Intervention Trial

Lignan intake, and its richest food source, flaxseed, have been associated with reduced breast cancer risk. Endogenous sex hormones, such as estrogens, play a role in breast cancer development, and lignans may alter these sex hormone levels. To assess the effect of flaxseed on circulating sex hormones, a randomized controlled trial was conducted among 99 postmenopausal women in Toronto, Canada. The intervention arm consumed 2 tablespoons (15 g) of ground flaxseed daily for 7 weeks; the control arm maintained usual diet. Baseline and week 7 concentrations of 14 serum sex hormones were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and immunoassay, and serum enterolignans (lignan biomarker) using LC-MS/MS. Intervention effects on sex hormone levels were assessed using analysis of covariance. Serum enterolignans increased among the flaxseed arm (+516%). Women consuming flaxseed (vs. controls) had increased serum 2-hydroxyestrone [treatment effect ratio (TER) = 1.54; 95% CI: 1.18-2.00] and 2:16α-hydroxyestrone ratio (TER =1.54; 95% CI: 1.15-2.06); effects on other hormones were not statistically significant. Within the flaxseed arm, change in enterolignan level was positively correlated with changes in 2-hydroxyestrone and 2:16α-hydroxyestrone ratio, and negatively with prolactin. Findings suggest flaxseed affects certain circulating sex hormone levels with possible implications for future breast cancer prevention research.

At-a-glance - What can social media tell us about the opioid crisis in Canada?

We explored social media as a potential data source for acquiring realtime information on opioid use and perceptions in Canada. Twitter messages were collected through a social media analytics platform between June 15, 2017, and July 13, 2017, and analyzed to identify recurring topics mentioned in the messages. Messages concerning the medical use of opioids as well as commentary on the Canadian government's current response efforts to the opioid crisis were common. The findings of this study may help to inform public health practice and community stakeholders in their efforts to address the opioid crisis.

Urinary bisphenol A and obesity in adults: results from the Canadian Health Measures Survey

INTRODUCTION

Exposure to bisphenol A (BPA) has been shown to affect lipid metabolism and promote weight gain in animal studies. Recent epidemiological studies also support a link between BPA and obesity in human populations, although many were limited to a single adiposity measure or have not considered potential confounding by dietary factors. The purpose of this study is to examine associations between urinary BPA and adiposity measures in a nationally representative sample of Canadian adults.

METHODS

We performed analyses using biomonitoring and directly measured anthropometric data from 4733 adults aged 18 to 79 years in the Canadian Health Measures Survey (2007-2011). We used multinomial and binary logistic regression models to estimate associations of urinary BPA with body mass index (BMI) categories (overweight vs. under/normal weight; obesity vs. under/normal weight) and elevated waist circumference (males: ≥ 102 cm; females: ≥ 88 cm), respectively, while controlling for potential confounders. Linear regression analyses were also performed to assess associations between urinary BPA and continuous BMI and waist circumference measures.

RESULTS

Urinary BPA was positively associated with BMI-defined obesity, with an odds ratio of 1.54 (95% confidence interval [CI]: 1.002-2.37) in the highest (vs. lowest) BPA quartile (test for trend, p = .041). Urinary BPA was not associated with elevated waist circumference defined using standard cut-offs. Additionally, each natural-log unit increase in urinary BPA concentration was associated with a 0.33 kg/m2 (95% CI: 0.10- 0.57) increase in BMI and a 1.00 cm (95% CI: 0.34-1.65) increase in waist circumference.

CONCLUSION

Our study contributes to the growing body of evidence that BPA is positively associated with obesity. Prospective studies with repeated measures are needed to address temporality and improve exposure classification.

Fall-related injuries among Canadian seniors, 2005-2013: an analysis of the Canadian Community Health Survey

INTRODUCTION

We describe the epidemiology and trends of fall-related injuries among Canadian seniors aged 65 years and older by sex and age, as well as the circumstances and consequences of their injuries.

METHODS

We analyzed nationally representative data from the 2005, 2009/2010 and 2013 samples of the Canadian Community Health Survey to calculate the number and rates of fall-related injuries for each survey year. Where possible, we combined data from two or more samples to estimate the proportion of fall-related injuries by type of injury, part of body injured, type of activity and type of treatment.

RESULTS

The rate of fall-related injuries among seniors increased from 49.4 to 58.8 per 1000 population between 2005 and 2013, during which the number of fall-related injuries increased by 54% overall. Women had consistently higher rates than men across all survey years, while rates increased with advancing age. The upward trend in fall-related injury rates was more prominent among women and younger age groups. The most common type of injury was broken or fractured bones (37%), and the shoulder or upper arm (16%) was the most commonly injured body part. Many fall-related injuries occurred while walking on a surface other than snow or ice (45%). Over 70% of seniors seeking treatment for their injuries visited a hospital emergency department.

CONCLUSION

Given the increase in both the number and rates of fall-related injuries over time, there is a need to continue monitoring trends and injury patterns associated with falls.

Risk factors for falls among seniors: implications of gender

Despite extensive literature on falls among seniors, little is known about gender-specific risk factors. To determine the prevalence of falls by gender and sociodemographic, lifestyle/behavioral, and medical factors, we conducted a cross-sectional study in a nationally representative sample of Canadian adults who were 65 years of age or older (n = 14,881) from the Canadian Community Health Survey-Healthy Aging (2008-2009). Logistic regression models were applied to investigate gender-specific associations between potential risk factors and falls. In men, stroke (odds ratio (OR) = 1.91), nutritional risk (OR = 1.86), post-secondary school degree (OR = 1.68), eye disorder (OR = 1.35), widowed/separated/divorced marital status (OR = 1.28), and arthritis (OR = 1.27) were independently associated with significantly higher odds of falls. In women, significant independent correlates of falls included stroke (OR = 1.53), age of 85 years or older (OR = 1.51), nutritional risk (OR = 1.39), consumption of at least 1 alcoholic drink per week (OR = 1.39), use of 5 or more medications (OR = 1.36), arthritis (OR = 1.36), diabetes (OR = 1.31), and osteoporosis (OR = 1.22). Higher physical activity levels were protective in both genders, and higher household income was protective in women. Gender should be considered when planning fall prevention strategies.

Epidemiology of work-related traumatic brain injury: a systematic review

OBJECTIVE

This systematic review aimed to describe the burden and risk factors of work-related traumatic brain injury (wrTBI) and evaluate methodological quality of existing literature on wrTBI.

METHODS

A search of electronic databases (MEDLINE, EMBASE, PsycINFO, and CINAHL) was conducted to identify articles published between 1980 and 2013 using a combination of terms for work, TBI, and epidemiology, without geographical limitations.

RESULTS

Ninety-eight studies were included in this review, of which 24 specifically focused on wrTBI. In general, male workers, those in the youngest and oldest age groups, and those working in the primary (e.g., agriculture, forestry, mining) or construction industries were more likely to sustain wrTBI, with falls being the most common mechanism of injury.

CONCLUSIONS

This review identified workers at highest risk of wrTBI, with implications for prevention efforts. Future research of better methodological quality is needed to provide a more complete picture of the epidemiology of wrTBI.

Osmotic regulation of airway reactivity by epithelium

Inhalation of nonisotonic solutions can elicit pulmonary obstruction in asthmatic airways. We evaluated the hypothesis that the respiratory epithelium is involved in responses of the airways to nonisotonic solutions using the guinea pig isolated, perfused trachea preparation to restrict applied agents to the mucosal (intraluminal) or serosal (extraluminal) surface of the airway. In methacholine-contracted tracheae, intraluminally applied NaCl or KCl equipotently caused relaxation that was unaffected by the cyclo-oxygenase inhibitor, indomethacin, but was attenuated by removal of the epithelium and Na+ and Cl- channel blockers. Na+-K+-2Cl- cotransporter and nitric oxide synthase blockers caused a slight inhibition of relaxation, whereas Na+,K+-pump inhibition produced a small potentiation. Intraluminal hyperosmolar KCl and NaCl inhibited contractions in response to intra- or extraluminally applied methacholine, as well as neurogenic cholinergic contractions elicited with electric field stimulation (+/- indomethacin). Extraluminally applied NaCl and KCl elicited epithelium-dependent relaxation (which for KCl was followed by contraction). In contrast to the effects of hyperosmolarity, intraluminal hypo-osmolarity caused papaverine-inhibitable contractions (+/- epithelium). These findings suggest that the epithelium is an osmotic sensor which, through the release of epithelium-derived relaxing factor, can regulate airway diameter by modulating smooth muscle responsiveness and excitatory neurotransmission.

Videomicroscopy of acute brain slices from amygdala and hippocampus

Video-enhanced contrast, differential-interference contrast microscopy (VEC-DICM) was used to visualize the cytoarchitecture and subcellular neuronal structure of acute brain slices from rat hippocampus and amygdala. Even at low-power magnification, the VEC-DICM system vastly improved our ability to visualize and examine the gross organization of the tissue. With medium-power magnification, the neuronal somata and proximal dendrites were clearly visible. With high-power magnification, some of the subcellular details could be clearly discerned--including cell nuclei, cell nucleoli, fine dendritic processes, and varicosities that may be synaptic expansions. We conclude that improved optical techniques should be valuable to cellular neurobiologists interested in structure-function relationships in brain slices.