Injury rates, severity, and drug testing programs in small construction companies

PROBLEM

Construction work is hazardous and workers consistently rank in the top of all occupations and industries for illicit drug and heavy alcohol use.

METHODS

Drug-testing programs were classified into three categories: no program, pre-employment/post-accident, and pre-employment/post-accident/random/suspicion. We analyzed workers' compensation claims from 1,360 construction companies over a six-year period to assess the possible association of testing program with injury rate.

RESULTS

Compared to no program, results respectively were RR=0.85 (CI=0.72-1.0) and RR=0.97 (CI=0.86-1.10) for all injuries, and RR=0.78 (CI=0.60-1.03) and RR=1.01 (CI=0.86-1.19) for lost-time injuries. Variability of results was exhibited across trade and union status, among other categories.

SUMMARY

Drug-testing programs may be associated with lower, non-significant, injury rates in this population.

IMPACT ON INDUSTRY

Drug-testing programs may be associated with lower injury rates, but care should be exercised to ensure accurate injury reporting, characterize underlying safety practices of a company, and to determine quality and consistency of testing.

Work-related violence against educators in Minnesota: rates and risks based on hours exposed

PROBLEM

Violence is a major occupational problem; yet, rigorous studies focused on educators to address this problem are limited. The objective was to identify educators' potential risks for physical assault (PA) and nonphysical violence (NPV), based on hours exposed.

METHODS

A total of 4,731 licensed kindergarten through grade 12 Minnesota educators, identified from the Minnesota Department of Education database, participated. Specially designed mailed questionnaires (12-month recall) enabled data collection. Calculated PA and NPV rates, per 100,000 working hours, used Poisson regression. Directed acyclic graphs identified confounders for multivariable analysis, adjusted for non-response and unknown eligibility.

RESULTS

The total PA rate was 5.3; PA risks increased for educators who: were non-married versus married; held master's degrees, or education specialist degrees, versus associate/bachelor's degrees; worked in public alternative and various school types, versus public schools; worked as social workers, in special education or multiple activities, versus standard classroom teaching; worked with <10, versus 10 to <25 students in the class. The total NPV rate was 26.4; subcategory rates were: threat (34.8); sexual harassment (7.6); verbal abuse (55.5); bullying (19.6). Increased risks for NPV included: 30-39 and 60-79, versus 50-59years of age; non-married versus married; working in public alternative versus public schools; working part-time or substitute, versus full-time; teaching in special education or multiple activities, versus standard classroom teaching; teaching in class sizes <10 and ≥25, versus 10-24 students; teaching in grades 3-12 and multiple grades, versus kindergarten to second grade. The investigated results for PA and NPV were similar, with a few exceptions. DISCUSSION AND IMPACT ON INDUSTRY: Results from this study provided information about factors associated with increased and decreased risks for violence against educators, based on hours worked. In addition, they provided a basis for further investigations to reduce violence against educators in the school environment.

Sunlight and other determinants of circulating 25-hydroxyvitamin D levels in black and white participants in a nationwide U.S. study

Circulating 25-hydroxyvitamin D (25(OH)D), a marker for vitamin D status, is associated with bone health and possibly cancers and other diseases; yet, the determinants of 25(OH)D status, particularly ultraviolet radiation (UVR) exposure, are poorly understood. Determinants of 25(OH)D were analyzed in a subcohort of 1,500 participants of the US Radiologic Technologists (USRT) Study that included whites (n = 842), blacks (n = 646), and people of other races/ethnicities (n = 12). Participants were recruited monthly (2008-2009) across age, sex, race, and ambient UVR level groups. Questionnaires addressing UVR and other exposures were generally completed within 9 days of blood collection. The relation between potential determinants and 25(OH)D levels was examined through regression analysis in a random two-thirds sample and validated in the remaining one third. In the regression model for the full study population, age, race, body mass index, some seasons, hours outdoors being physically active, and vitamin D supplement use were associated with 25(OH)D levels. In whites, generally, the same factors were explanatory. In blacks, only age and vitamin D supplement use predicted 25(OH)D concentrations. In the full population, determinants accounted for 25% of circulating 25(OH)D variability, with similar correlations for subgroups. Despite detailed data on UVR and other factors near the time of blood collection, the ability to explain 25(OH)D was modest.

Brain cancer in workers employed at a specialty chemical research facility

ABSTRACT This study evaluated unique exposures and their relationship to brain cancer mortality in employees of a specialty chemical research facility. Following an exposure assessment that concerned compounds distinct to this facility, the authors conducted a cohort mortality study of 5,284 workers to assess mortality in reference to the general population and a nested case-control study to evaluate brain cancer risk associated with specific jobs and unique chemical exposures. Four hundred eighty-six deaths, including 14 brain cancer deaths, were identified. Overall mortality was lower than expected. Brain cancer mortality was elevated (standardized mortality ratio [SMR] = 2.02, 95% confidence interval [CI] = 1.11-3.40). Exposures to 5 specific chemical categories were assessed. Exploration of work history and the specific chemical exposures did not explain the brain cancer cases. No clear occupational etiology was identified.

Variability and reproducibility of circulating vitamin D in a nationwide U.S. population

CONTEXT

Most studies examining associations between circulating vitamin D and disease are based on a single measure of vitamin D, which may not reflect levels over time, particularly because vitamin D concentrations vary by season. Few studies evaluated how well multiple 25-hydroxyvitamin D [25(OH)D] measures track within the same individual over time.

OBJECTIVE

This study examined variability and reproducibility of vitamin D by evaluating repeat measurements of plasma 25(OH)D concentrations while accounting for determinants of circulating concentrations including dietary supplement use and latitude of residence from a population of U.S. radiologic technologists.

DESIGN AND PARTICIPANTS

We analyzed circulating 25(OH)D in blood samples taken from 538 men and women from a prospective, nationwide study at two time points within a 1-yr period, most measured in different seasons. Inter- and intra-individual variability, reliability coefficients, and measurement error were examined.

RESULTS

The spearman rank correlation between two measurements of 25(OH)D concentrations was moderate (r = 0.75, P < 0.001) and did not vary significantly by participant characteristics including age, race, or latitude. The intraclass correlation coefficient was 0.72 (95% confidence interval = 0.68-0.76). The deattenuation factor of plasma 25(OH)D levels was 1.39, suggesting that a single measure of vitamin D on a continuous scale in regression analyses may result in attenuated relationships of about 40%.

CONCLUSION

Our results suggest that a single blood sample obtained in spring or fall provides a reasonable average for 25(OH)D over a 1-yr period, but additional studies are needed to estimate variability and agreement in plasma 25(OH)D measurements over longer intervals and younger populations.

Estimates of restrictive ventilatory defect in the mining industry. Considerations for epidemiological investigations: a cross-sectional study

OBJECTIVES

(1) To assess the impact of American Thoracic Society and European Respiratory Society (ATS/ERS) 'acceptability' and 'usability' criteria for spirometry on the estimates of restrictive ventilatory defect in a population of taconite miners. (2) To compare estimates of restrictive ventilatory defect with three different pulmonary function tests (spirometry, alveolar volume (VA) and diffusing capacity (DL,CO)). (3) To assess the role of population characteristics on these estimates.

DESIGN

Cross-sectional study.

SETTING

Current and former workers in six current taconite mining operations of northeastern Minnesota were surveyed.

PARTICIPANTS

We attempted to enrol 3313 participants. Of these, 1353 responded while 1188 current and former workers fully participated in the survey and 1084 performed complete pulmonary function testing and were assessed.

PRIMARY AND SECONDARY OUTCOME MEASURES

We applied ATS/ERS acceptability criteria for all tests and categorised participants into groups according to whether they fully met, partially met or did not meet acceptability criteria for spirometry. Obstruction and restriction were defined utilising the lower limit of normal for all tests. When using VA, restriction was identified after excluding obstruction.

RESULTS

Only 519 (47.9%) tests fully met ATS/ERS spirometry acceptability criteria. Within this group, 5% had obstruction and 6%, restriction on spirometry. In contrast, among all participants (N=1084), 16.8% had obstruction, while 4.5% had restriction. VA showed similar results in all groups after obstruction was excluded. Impaired gas transfer (reduced DL,CO) was identified in less than 50% of restriction identified by either spirometry or VA. Body mass index (BMI) was significantly related to spirometric restriction in all groups.

CONCLUSIONS

Population estimates of restriction using spirometry or VA varied by spirometric acceptability criteria. Other factors identified as important considerations in the estimation of restrictive ventilatory defect included increased BMI and gas transfer impairment in a relatively smaller proportion of those with spirometric restriction. These insights are important when interpreting population-based physiological data in occupational settings.

Basal cell carcinoma and anthropometric factors in the U.S. radiologic technologists cohort study

Basal cell carcinoma (BCC) is the most common cancer in Caucasian populations. Although several risk factors are well-established, including ultraviolet radiation (UVR) sensitivity and exposure, few studies have examined anthropometric measures and BCC. Using Cox proportional hazards regression analysis, we prospectively investigated the relationship between height, weight and body mass index (BMI) and BCC in 58,213 Caucasian participants (11,631 men and 46,582 women) from the United States Radiological Technologists cohort. This analysis was limited to participants who were cancer-free at baseline. The baseline questionnaire provided self-reported anthropometric factors and the subsequent questionnaire collected skin cancer susceptibility factors, lifetime UVR exposure derived from residential and personal UVR exposure (time outdoors) and health outcomes. During 509,465 person-years of follow-up, we identified 2,291 BCC cases (486 men; 1,805 women). BCC risk increased with increasing height, and decreased with increasing weight and BMI in both sexes, even after adjusting for UVR susceptibility factors and exposures. For BMI categories: <25 (reference); 25-<30; 30-<35 and ≥ 35 kg m(-2) , multivariate hazard ratios (HR) in women were: 1.00; 0.74 (95% CI = 0.66-0.83); 0.67 (0.56-0.81) and 0.57 (0.44-0.74), respectively, p-trend ≤ 0.0001. Risks were similar in men. The inverse association between BMI and BCC was unaffected by controlling for sun-related exposures. Nevertheless, it may at least partly reflect residual UVR confounding. Further research with more detailed sun exposure data, including clothing patterns, would help clarify the relationship between BMI and BCC.

Use of nonsteroidal anti-inflammatory drugs and risk of basal cell carcinoma in the United States Radiologic Technologists study

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been associated with reduced risk of colorectal and other cancers, but the association with basal cell carcinoma (BCC) is unclear. Previous epidemiological studies have been small in size, conducted in especially vulnerable populations, or have not accounted for solar ultraviolet exposure, a major risk factor for BCC. In the United States Radiologic Technologists cohort, we followed subjects to assess NSAID use on risk of first incident BCC. We included Caucasian participants who responded to both second and third questionnaires (administered from 1994 to 1998 and 2003 to 2005, respectively), and who reported no cancer at the time of the second questionnaire, N = 58,213. BCC, constituent risk factors (e.g., eye color, complexion, hair color) and sun exposure history were assessed through self-administered survey. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards models. Of the 58,213 people in the study population, 2,291 went on to develop BCC. Any NSAID use was not associated with subsequent incidence of BCC (HR = 1.04, 95% CI: 0.92-1.16) after adjusting for age, sex and estimated lifetime summer sun exposure. Neither association was observed when stratified by NSAID type (aspirin and other NSAIDs), nor did dose-response patterns emerge by frequency of use (average days per month). Further analyses did not reveal interaction with sex, birth cohort, smoking, alcohol consumption, sun exposure, occupational radiation exposure or personal risk factors for BCC. In this large nationwide study, we observed no association between NSAID use and subsequent BCC risk.

Common genetic variants in the 8q24 region and risk of papillary thyroid cancer

OBJECTIVES/HYPOTHESIS

Single nucleotide polymorphisms (SNPs) in the 8q24 chromosomal region identified from genome-wide scans have been associated with the risk of several cancers, including breast (rs1562430), prostate (rs1447295), and colon (rs6983267). A genome-wide scan in 26 families with papillary thyroid cancer (PTC) also found susceptibility loci in 8q24, supporting a closer evaluation of this chromosomal region in relation to the risk of sporadic PTC.

STUDY DESIGN

Case-control study.

METHODS

We evaluated 157 tag SNPs in the 8q24 chromosomal region between 120.91 Mb and 128.78 Mb (including rs1562430, rs1447295, and rs6983267) in a case-control study of 344 PTC cases and 452 age and gender frequency-matched controls. We used logistic regression to estimate odds ratios and compute P values of linear trend for PTC with genotypes of interest. To account for multiple comparisons, we applied the false discovery rate (FDR) method.

RESULTS

We did not find a significant association between rs1562430, rs1447295, or rs6983267 and PTC risk. We found that one SNP (rs4733616) was associated with PTC risk at P = .003, and 12 other SNPs were associated with PTC risk at P < .05. However, no SNPs remained significant after FDR correction.

CONCLUSIONS

Our findings do not support a strong association between SNPs in the 8q24 chromosomal region and risk of sporadic PTC, but several SNPs with small effects might exist.

Lower acetylcholinesterase activity among children living with flower plantation workers

BACKGROUND

Children of workers exposed to pesticides are at risk of secondary pesticide exposure. We evaluated the potential for lower acetylcholinesterase activity in children cohabiting with fresh-cut flower plantation workers, which would be expected from organophosphate and carbamate insecticide exposure. Parental home surveys were performed and acetylcholinesterase activity was measured in 277 children aged 4-9 years in the Secondary Exposure to Pesticides among Infants, Children and Adolescents (ESPINA) study. Participants lived in a rural county in Ecuador with substantial flower plantation activity.

RESULTS

Mean acetylcholinesterase activity was 3.14 U/ml, standard deviation (SD) of 0.49. It was lower by 0.09 U/ml (95% confidence interval (CI) -0.19, -0.001) in children of flower workers (57% of participants) than non-flower workers' children, after adjustment for gender, age, height-for-age, hemoglobin concentration, income, pesticide use within household lot, pesticide use by contiguous neighbors, examination date and residence distance to nearest flower plantation. Using a 4 level polychotomous acetylcholinesterase activity dependent variable, flower worker cohabitation (vs. not) had odds ratio 3.39 (95% CI 1.19, 9.64) for being <15th percentile compared to the highest tertile. Children cohabitating for ≥5 years (vs. never) had OR of 4.11 (95% CI: 1.17, 14.38) of AChE activity within <15th percentile compared to the highest tertile.

CONCLUSIONS

Cohabitation with a flower worker was related to lower acetylcholinesterase activity in children. This supports the hypothesis that the amount of take-home pesticides from flower workers suffices to decrease acetylcholinesterase activity, with lower activity associated with longer exposure.

Retrospective exposure assessment in a chemical research and development facility

The objective of this exposure assessment was to reconstruct cumulative historical exposures for workers who have been exposed to multiple chemicals and chemical groups to better understand a cluster of brain cancers within a research and development lab. Chemicals of interest, including acrylates, bis-chloromethyl ether (BCME), chloromethyl methyl ether (CMME), isothiazolones and nitrosoamines, were selected on the basis of the plausibility of penetrating the blood-brain barrier and the uniqueness of the chemical's biological activity. In a complicated exposure setting such as a chemical R&D facility, multiple exposure estimation methods were needed. First, similarly exposure groups (SEGs) were created for these materials based on department group, time period of the department's existence and function associated with job titles. A probabilistic framework for assessing exposures was developed using Bayesian analysis of historical monitoring data, mathematical exposure modeling and professional judgments of current and former industrial hygienists at the facility were used to reconstruct the exposure history for acrylates, BCME and CMME for each SEG over the time period of interest. Since sufficient measurement data for isothiazolones and nitrosoamines were not available, the exposure histories for each SEG for these chemicals were estimated. This was done using objective formaldehyde levels and subjective employee interviews. The interviews assessed workplace determinants of exposure as distinct surrogates for estimating inhalation and dermal exposures. The exposure assessments by these methods were compared against each other to estimate the potential for exposure misclassification. A job exposure matrix (JEM) was constructed that contained the exposures obtained from above multiple approaches for each of these chemical groups for each SEG for each year of interest. The combination of methods used in this work is a unique and potentially helpful framework that can be used in analogous workplace settings involving multiple exposures with incomplete objective measurement information.

Radiographic evidence of nonoccupational asbestos exposure from processing Libby vermiculite in Minneapolis, Minnesota

BACKGROUND

Community exposure to asbestos from contaminated vermiculite ore from Libby, Montana, occurred in many processing sites in the United States, including a densely populated urban residential neighborhood of Minneapolis, Minnesota.

OBJECTIVE

We examined exposed community residents who never worked at the plant or never lived with a plant worker for radiographic evidence of lung changes consistent with asbestos exposure.

METHODS

We obtained posteroanterior chest radiographs to identify the prevalence of pleural abnormalities consistent with pneumoconiosis, as determined by consensus of two National Institute for Occupational Safety and Health-certified B-reader radiologists. We estimated cumulative asbestos exposure (fibers per cubic centimeters × months) with air dispersion model data and activity-based modeled exposure estimates for vermiculite processing waste contact. We modeled associations between pleural abnormalities and asbestos exposure using multiple logistic regression to adjust for year of birth, sex, and potential occupational asbestos exposure.

RESULTS

Radiographs were obtained for 461 participants. The prevalence of pleural abnormalities by B-reader consensus was 10.8%. A history of direct contact with the waste and ever playing in the waste piles was associated with pleural abnormalities {odds ratio [OR] 2.78 [95% confidence interval (CI): 1.26, 6.10] and 2.17 (95% CI: 0.99, 4.78), respectively, when adjusted for background exposure}. The regression coefficients for log-transformed measures (fibers per cubic centimeters × months) of background exposure and activity-based exposure were 0.322 (95% CI: 0.078, 0.567) and 0.063 (95% CI: -0.013, 0.139), respectively, when adjusted for each other, and 0.283 (95% CI: 0.104, 0.463) for cumulative exposure from all sources.

CONCLUSION

These results support the hypothesis that community exposure to asbestos-contaminated vermiculite originating from Libby, Montana, is associated with measurable effects based on radiographic evidence.

Modeling community asbestos exposure near a vermiculite processing facility: Impact of human activities on cumulative exposure

Contaminated vermiculite ore from Libby, Montana was processed in northeast Minneapolis from 1936 to 1989 in a densely populated urban residential neighborhood, resulting in non-occupational exposure scenarios from plant stack and fugitive emissions as well as from activity-based scenarios associated with use of the waste rock in the surrounding community. The objective of this analysis was to estimate potential cumulative asbestos exposure for all non-occupationally exposed members of this community. Questionnaire data from a neighborhood-exposure assessment ascertained frequency of potential contact with vermiculite processing waste. Monte Carlo simulation was used to develop exposure estimates based on activity-based concentration estimates and contact durations for four scenarios: S1, moved asbestos-contaminated waste; S2, used waste at home, on lawn or garden; S3, installed/removed vermiculite insulation; S4, played in or around waste piles at the plant. The simulation outputs were combined with air-dispersion model results to provide total cumulative asbestos exposure estimates for the cohort. Fiber emissions from the plant were the largest source of exposure for the majority of the cohort, with geometric mean cumulative exposures of 0.02 fibers/cc × month. The addition of S1, S2 and S3 did not significantly increase total cumulative exposure above background exposure estimates obtained from dispersion modeling. Activity-based exposures were a substantial contributor to the upper end of the exposure distribution: 90th percentile S4 exposure estimates are ∼10 times higher than exposures from plant emissions. Pile playing is the strongest source of asbestos exposure in this cohort, with other activity scenarios contributing less than from plant emissions.

Balancing work and family after childbirth: a longitudinal analysis

BACKGROUND

in the United States, women with young children have dramatically increased their participation in the workforce, resulting in greater potential conflict between work and family roles. However, few studies have examined postpartum work-family conflict. This study examined associations between work-family conflict and women's health after childbirth.

METHODS

employed women, 18 years of age and older, were recruited while hospitalized for childbirth and followed for 18 months (n = 541; 66% response rate). Health outcomes were measured using the Short Form 12, version 2. Longitudinal fixed-effects models estimated the associations between work-family conflict (modeled as job and home spillover) and health.

RESULTS

women who reported high levels of job spillover to home had mental health scores slightly, but significantly, worse than women who reported low levels of spillover (β = -1.26; SE = 0.47). Women with medium and high levels of home spillover to job also reported worse mental health (β = -0.81, SE = 0.30; and β = -1.52, SE = 0.78) relative to those with low spillover. Women who reported medium (versus low) levels of home spillover reported slightly improved physical health (β = 0.64, SE = 0.30). There was no significant association between job spillover and physical health.

CONCLUSION

this study focused exclusively on employed postpartum women. Results illustrate that job and home spillover are associated with maternal mental and physical health. Findings also revealed that flexible work arrangements were associated with poorer postpartum mental health scores, which may reflect unintended consequences, such as increasing the amount of work brought home.

Polymorphisms in oxidative stress and inflammation pathway genes, low-dose ionizing radiation, and the risk of breast cancer among US radiologic technologists

OBJECTIVE

Ionizing radiation, an established breast cancer risk factor, has been shown to induce oxidative damage and chronic inflammation. Polymorphic variation in oxidative stress and inflammatory-mediated pathway genes may modify radiation-related breast cancer risk.

METHODS

We estimated breast cancer risk for 28 common variants in 16 candidate genes involved in these pathways among 859 breast cancer cases and 1,083 controls nested within the US Radiologic Technologists cohort. We estimated associations between occupational and personal diagnostic radiation exposures with breast cancer by modeling the odds ratio (OR) as a linear function in logistic regression models and assessed heterogeneity of the dose-response across genotypes.

RESULTS

There was suggestive evidence of an interaction between the rs5277 variant in PTGS2 and radiation-related breast cancer risk. The excess OR (EOR)/Gy from occupational radiation exposure = 5.5 (95%CI 1.2-12.5) for the GG genotype versus EOR/Gy < 0 (95%CI < 0-3.8) and EOR/Gy < 0 (95%CI < 0-14.8) for the GC and CC genotypes, respectively, (p (interaction) = 0.04). The association between radiation and breast cancer was not modified by other SNPs examined.

CONCLUSIONS

This study suggests that variation in PTGS2 may modify the breast cancer risk from occupational radiation exposure, but replication in other populations is needed to confirm this result.

Multiple indicators of ambient and personal ultraviolet radiation exposure and risk of non-Hodgkin lymphoma (United States)

Recent epidemiologic studies have suggested that ultraviolet radiation (UV) may protect against non-Hodgkin lymphoma (NHL), but few, if any, have assessed multiple indicators of ambient and personal UV exposure. Using the US Radiologic Technologists study, we examined the association between NHL and self-reported time outdoors in summer, as well as average year-round and seasonal ambient exposures based on satellite estimates for different age periods, and sun susceptibility in participants who had responded to two questionnaires (1994-1998, 2003-2005) and who were cancer-free as of the earlier questionnaire. Using unconditional logistic regression, we estimated the odds ratio (OR) and 95% confidence intervals for 64,103 participants with 137 NHL cases. Self-reported time outdoors in summer was unrelated to risk. Lower risk was somewhat related to higher average year-round and winter ambient exposure for the period closest in time, and prior to, diagnosis (ages 20-39). Relative to 1.0 for the lowest quartile of average year-round ambient UV, the estimated OR for successively higher quartiles was 0.68 (0.42-1.10); 0.82 (0.52-1.29); and 0.64 (0.40-1.03), p-trend=0.06), for this age period. The lower NHL risk associated with higher year-round average and winter ambient UV provides modest additional support for a protective relationship between UV and NHL.

Radiation Organ Doses Received by U.S. Radiologic Technologists: Estimation Methods and Findings

Abstract In this paper, we describe recent methodological enhancements and findings from the dose reconstruction component of a study of cancer risks among U.S. radiologic technologists. An earlier version of the dosimetry published in 2006 (Simon et al., Radiat. Res. 166, 174-192, 2006) used physical and statistical models, literature-reported exposure measurements for the years before 1960, and archival personnel monitoring badge data from cohort members through 1984. The data and models were used to estimate unknown occupational radiation doses for 90,000 radiological technologists, incorporating information about each individual's employment practices based on a survey conducted in the mid-1980s. The dosimetry methods presented here, while using many of the same methods as before, now estimate annual and cumulative occupational badge doses (personal dose equivalent) to about 110,000 technologists for each year worked from 1916 to 2006, but with numerous methodological improvements. This dosimetry, using much more comprehensive information on individual use of protection aprons, estimates radiation absorbed doses to 12 organs and tissues (red bone marrow, ovary, colon, brain, lung, heart, female breast, skin of trunk, skin of head and neck and arms, testes, thyroid and lens of the eye). Every technologist's annual dose is estimated as a probability density function (pdf) to account for shared and unshared uncertainties. Major improvements in the dosimetry methods include a substantial increase in the number of cohort member annual badge dose measurements, additional information on individual apron use obtained from surveys conducted in the 1990s and 2005, refined modeling to develop annual badge dose pdfs using Tobit regression, refinements of cohort-based annual badge pdfs to delineate exposures of highly and minimally exposed individuals and to assess minimal detectable limits more accurately, and extensive refinements in organ dose conversion coefficients to account for uncertainties in radiographic techniques employed. For organ dose estimation, we rely on well-researched assumptions about critical exposure-related variables and their changes over the decades, including the peak kilovoltage and filtration typically used in conducting radiographic examinations and the usual body location for wearing radiation monitoring badges. We have derived organ dose conversion coefficients based on air-kerma weighting of photon fluences from published X-ray spectra and derived energy-dependent transmission factors for protective aprons of different thicknesses. We tailor bone marrow dose estimates to individual cohort members by using an individual-specific body mass index correction factor. To our knowledge the models and reconstructed doses presented herein represent the most comprehensive dose reconstructions undertaken for a cohort of medical radiation workers.

Sunlight, hormone replacement status and colorectal cancer risk in postmenopausal women

A reanalysis of the Women's Health Initiative (WHI) randomized clinical trial found a significant interaction between supplementation with vitamin D/calcium and estrogen therapy and the risk of colorectal cancer risk, with reduced risks from supplementation limited to the placebo arms of the estrogen trials. To explore whether the vitamin D effects are modified by estrogen therapy, we report a largely cross-sectional, analysis of the association between sun exposure, which is an important vitamin D source, and colorectal cancer risk among postmenopausal women in the U.S. Radiologic Technologists study. Among 21,695 participants, there were a total of 108 cases. Sun exposure was based on time outdoors and on ambient ultraviolet radiation (UV) exposure based on residence linked to erythemal exposures derived from the Total Ozone Mapping Spectrometer database. Although there was no relationship between outdoor time or ambient UV measure and colorectal cancer risk in current hormone replacement therapy (HRT) users, in never/past HRT users, there was an inverse association with higher ambient UV exposure, RR for highest vs. lowest tertile = 0.40; 95% CI 017, 0.93; p for trend = 0.04. Non-significant lower risks were also associated with higher levels of outdoor time (> or = 3.5 hr/week) in never/past HRT users. The interaction between both indicators of sun exposure and HRT and CRC risk was not significant. These data, although exploratory, are consistent with evidence from the WHI suggesting a decrease in colorectal cancer risk may be associated with vitamin D exposure among postmenopausal women who are not taking HRT, but not among current HRT users.

Novel breast cancer risk alleles and interaction with ionizing radiation among U.S. radiologic technologists

As genome-wide association studies of breast cancer are replicating findings and refinement studies are narrowing the signal location, additional efforts are necessary to elucidate the underlying functional relationships. One approach is to evaluate variation in risk by genotype based on known breast carcinogens, such as ionizing radiation. Given the public health concerns associated with recent increases in medical radiation exposure, this approach may also identify potentially susceptible subpopulations. We examined interaction between 27 newly identified breast cancer risk alleles (identified within the NCI Cancer Genetic Markers of Susceptibility and the Breast Cancer Association Consortium genome-wide association studies) and occupational and medical diagnostic radiation exposure among 859 cases and 1083 controls nested within the United States Radiologic Technologists cohort. We did not find significant variation in the radiation-related breast cancer risk for the variant in RAD51L1 (rs10483813) on 14q24.1 as we had hypothesized. In exploratory analyses, we found that the radiation-associated breast cancer risk varied significantly by linked markers in 5p12 (rs930395, rs10941679, rs2067980 and rs4415084) in the mitochondrial ribosomal protein S30 (MRPS30) gene (P(interaction) = 0.04). Chance, however, may explain these findings, and as such, these results need to be confirmed in other populations with low to moderate levels of radiation exposure. Even though a complete understanding of the way(s) in which these variants may increase breast cancer risk remains elusive, this approach may yield clues for further investigation.

Biomonitoring data for 2,4-dichlorophenoxyacetic acid in the United States and Canada: interpretation in a public health risk assessment context using Biomonitoring Equivalents

BACKGROUND

Several extensive studies of exposure to 2,4-dichlorophenoxyacetic acid (2,4-D) using urinary concentrations in samples from the general population, farm applicators, and farm family members are now available. Reference doses (RfDs) exist for 2,4-D, and Biomonitoring Equivalents (BEs; concentrations in urine or plasma that are consistent with those RfDs) for 2,4-D have recently been derived and published.

OBJECTIVE

We reviewed the available biomonitoring data for 2,4-D from the United States and Canada and compared them with BE values to draw conclusions regarding the margin of safety for 2,4-D exposures within each population group.

DATA SOURCES

Data on urinary 2,4-D excretion in general and target populations from recent published studies are tabulated and the derivation of BE values for 2,4-D summarized.

DATA SYNTHESIS

The biomonitoring data indicate margins of safety (ratio of BE value to biomarker concentration) of approximately 200 at the central tendency and 50 at the extremes in the general population. Median exposures for applicators and their family members during periods of use appear to be well within acute exposure guidance values.

CONCLUSIONS

Biomonitoring data from these studies indicate that current exposures to 2,4-D are below applicable exposure guidance values. This review demonstrates the value of biomonitoring data in assessing population exposures in the context of existing risk assessments using the BE approach. Risk managers can use this approach to integrate the available biomonitoring data into an overall assessment of current risk management practices for 2,4-D.

Bystander injury evaluation of children from midwestern agricultural operations

BACKGROUND

With more than a million youth living on agricultural operations, it is important for parents to understand the consequences of bystander injuries that children experience in these environments. We identified the childhood injuries for bystander status and compared the severity of these injuries to the working children in the Regional Rural Injury Study-II (RRIS-II).

METHODS

RRIS-II followed 16,546 children ( approximately 85% of eligible) from rural communities in the Midwest for two six-month recall periods in 1999 and 2001. Demographic, injury, and exposure data were collected through comprehensive computer-assisted telephone interviews. Child injuries were cataloged using narrative scenarios into four categories: (a) directly work-related; (b) indirectly work-related; (c) non-working accomplice; and (d) non-working attendant; the latter three all being bystander categories. Poisson regression modeling was used to calculate rates of bystander injuries. Frequencies were used for comparison of severity measures.

RESULTS

Among the 463 child injuries (aged <20yrs), 102 were bystander injuries. Of the bystander-related injuries, 14 were identified as indirectly work-related (working bystanders), 27 as non-working accomplice (passengers/tag-alongs), and 60 as non-working attendant (playing on the operation). The overall rate of bystander injuries was 6.4 per 1,000 people, 95% CI (5.0, 8.1). Males, compared with females, had more than twice the injury rate (8.7; 95% CI 6.4-11.8, and 3.9; 95% CI 2.7-5.7, per 1,000 people, respectively). Bystanders in this population had more severe injuries with 4% having life-threatening circumstances; of these, 4% of the accomplices and 2% of the attendants subsequently died.

CONCLUSIONS

Children who live or work on agricultural operations are vulnerable to many hazards. Therefore, this study examined child injuries and found a clear difference in the consequences of these injuries between working-related and bystanding-related injuries.

IMPACT ON INDUSTRY

Unlike occupations such as construction and mining, where laws and organizations have been created for the protection of bystanders, agricultural bystanders have remained unprotected and have had to face the consequent injury and death outcomes. As public health professionals considering these risks, it is necessary that we work to develop more intervention studies and continue to propose suggestive guidelines for child safety in these environments so as to challenge family traditions and possibly spark public policies that will give further protection to this population.

Nonradiation risk factors for thyroid cancer in the US Radiologic Technologists Study

The incidence of thyroid cancer has been rapidly increasing in the United States, but few risk factors have been established. The authors prospectively examined the associations of self-reported medical history, anthropometric factors, and behavioral factors with thyroid cancer risk among 90,713 US radiologic technologists (69,506 women and 21,207 men) followed from 1983 through 2006. Incident thyroid cancers in 242 women and 40 men were reported. Elevated risks were observed for women with benign thyroid conditions (hazard ratio (HR) = 2.35, 95% confidence interval (CI): 1.73, 3.20), benign breast disease (HR = 1.56, 95% CI: 1.08, 2.26), asthma (HR = 1.68, 95% CI: 1.00, 2.83), and body mass index > or =35.0 versus 18.5-24.9 kg/m(2) (HR = 1.74, 95% CI: 1.03, 2.94; P-trend = 0.04). Current smoking was inversely associated with thyroid cancer risk (HR = 0.54). No clear associations emerged for reproductive factors, other medical conditions, alcohol intake, or physical activity. Despite few thyroid cancers in men, men with benign thyroid conditions had a significantly increased risk of thyroid cancer (HR = 4.65, 95% CI: 1.62, 13.34), and results for other risk factors were similar to those for women. Consistent with prior studies, obesity and benign thyroid conditions increased and current smoking decreased the risk of thyroid cancer. The novel findings for benign breast disease and asthma warrant further investigation.

Child bystanding: A risk factor for injury and identifying its' determinants on midwestern agricultural operations

BACKGROUND

Agriculture is considered among the most dangerous occupations and has consistently ranked among the top three. Production processes, associated with this occupation, place at risk not only workers but also others who live on the operations. We evaluated the incidence and determinants of associated bystander injuries in the Regional Rural Injury Study-II (RRIS-II).

METHODS

The RRIS-II followed 32,601 people ( approximately 85% of eligible) from rural communities in the Midwest for 1999 and 2001, using six-month recall periods, and identified their injury events. Demographic, injury, and exposure data were collected through comprehensive and case-control computer-assisted telephone interviews. Multivariate logistic regression analyses were used to estimate the risk of child bystanding and agricultural injury, while controlling for potentially confounding variables.

RESULTS

Nearly 60% of all 425-child injury cases (<20 years) responded to sometimes/frequently bystanding in six out of seven different agricultural environments (e.g., workshops, animal areas, etc.) Multivariate regression analyses, with odds ratios and 95% confidence intervals, showed increased odds of injury for bystanding near used (1.5; 1.1, 1.9) or stored (1.4; 1.1, 1.8) machinery, and near fields and barnyards (1.4; 1.0, 1.9). Further, multivariate analyses revealed increased odds of bystanding for parental beliefs, such as: child age (1.4; 1.0, 2.0) near stored equipment. Parental levels of strictness were also evaluated and showed decreased odds of bystanding when the parents were not strict about the child's wearing a seatbelt near used equipment (0.5; 0.3, 1.0). Households with only one child had decreased odds of bystanding for five of the exposures while there was an increased odds of bystanding near animals for households with five or more children.

CONCLUSIONS

Although parents cannot child-proof their operations, it is important for them to understand the apparent odds of and risks associated with bystanding. Children can have injury odds similar to adults in this environment; therefore, it is necessary to examine parental factors that may be associated with children's likelihood of bystanding in high-risk work environments.

School resources, resource allocation, and risk of physical assault against Minnesota educators

To investigate the relation between schools' resource levels (i.e., annual per student expenditures), school resource allocations, and physical assault (PA) against Minnesota's educators, a study was conducted from the two-phase Minnesota Educators' Study (MES) that incorporated school-level fiscal and demographic data from the Minnesota Department of Education (MDE). The MES examined a randomly selected cohort of employed, state-licensed kindergarten through grade 12 educators. From mailed questionnaires, response rates for both Phase I (comprehensive data collection on violent events) and Phase II (case-control) were 84%. Cases experienced a work-related PA event in the previous 12 months; controls reported no assaults. Based on the school in which they worked the most time and available MDE school-level data, together with MES questionnaire data, analyses were conducted on 238 cases and 640 controls. Multivariate analyses, using directed acyclic graphs to guide selection of confounders, suggested that increased spending (i.e. resources) was associated with decreased risk of PA. Analyses further suggested that the highest quartiles of resource allocations, compared with the lowest quartiles (referents), were associated with decreased risks of PA for: district level administration; regular instruction; special education; student activities and athletics; and pupil support services expenditures. Associations between increased resource allocations to student activities expenditures and decreased risks of PA were the strongest. For example, an allocation greater than 5% of the total annual per student expenditure to student activities programming (referent, less than 0.04%) was associated with a decreased risk of PA (OR=0.30, 95% CI: 0.12, 0.77). Results suggested that allocations of school resources (i.e., expenditures) to key program areas such as student athletics and extracurricular activities may reduce risk of work-related PA against educators. Research to further explore the nature of the relations between disparities in school resources and spending, resource allocations, and PA will be important to the continued development of relevant prevention strategies.