James E. Lockey

Cancer Risk Among Firefighters: A Review and Meta-analysis of 32 Studies

Objective: The objective of this study was to review 32 studies on firefighters and to quantitatively and qualitatively determine the cancer risk using a meta-analysis. Methods: A comprehensive search of computerized databases and bibliographies from identified articles was performed. Three criteria used to assess the probable, possible, or unlikely risk for 21 cancers included pattern of meta-relative risks, study type, and heterogeneity testing. Results: The findings indicated that firefighters had a probable cancer risk for multiple myeloma with a summary risk estimate (SRE) of 1.53 and 95% confidence interval (CI) of 1.21–1.94, non-Hodgkin lymphoma (SRE = 1.51, 95% CI = 1.31–1.73), and prostate (SRE = 1.28; 95% CI = 1.15–1.43). Testicular cancer was upgraded to probable because it had the highest summary risk estimate (SRE = 2.02; 95% CI = 1.30–3.13). Eight additional cancers were listed as having a “possible” association with firefighting. Conclusions: Our results confirm previous findings of an elevated metarelative risk for multiple myeloma among firefighters. In addition, a probable association with non-Hodgkin lymphoma, prostate, and testicular cancer was demonstrated.

A Comparison of Proximity and Land Use Regression Traffic Exposure Models and Wheezing in Infants

Background We previously reported an association between infant wheezing and residence < 100 m from stop-and-go bus and truck traffic. The use of a proximity model, however, may lead to exposure misclassification. Objective Results obtained from a land use regression (LUR) model of exposure to truck and bus traffic are compared with those obtained with a proximity model. The estimates derived from the LUR model were then related to infant wheezing. Methods We derived a marker of diesel combustion—elemental carbon attributable to traffic sources (ECAT)—from ambient monitoring results of particulate matter with aerodynamic diameter < 2.5 μm. We developed a multiple regression model with ECAT as the outcome variable. Variables included in the model were locations of major roads, bus routes, truck traffic count, and elevation. Model parameter estimates were applied to estimate individual ECAT levels at infants’ homes. Results The levels of estimated ECAT at the monitoring stations ranged from 0.20 to 1.02 μg/m3. A LUR model of exposure with a coefficient of determination (R2) of 0.75 was applied to infants’ homes. The mean (± SD) ambient exposure of ECAT for infants previously categorized as unexposed, exposed to stop-and-go traffic, or exposed to moving traffic was 0.32 ± 0.06, 0.42 ± 0.14, and 0.49 ± 0.14 μg/m3, respectively. Levels of ECAT from 0.30 to 0.90 μg/m3 were significantly associated with infant wheezing. Conclusions The LUR model resulted in a range of ECAT individually derived for all infants’ homes that may reduce the exposure misclassification that can arise from a proximity model.

High environmental relative moldiness index during infancy as a predictor of asthma at 7 years of age

BACKGROUND Mold exposures may contribute to the development of asthma, but previous studies have lacked a standardized approach to quantifying exposures. OBJECTIVE To determine whether mold exposures at the ages of 1 and/or 7 years were associated with asthma at the age of 7 years. METHODS This study followed up a high-risk birth cohort from infancy to 7 years of age. Mold was assessed by a DNA-based analysis for the 36 molds that make up the Environmental Relative Moldiness Index (ERMI) at the ages of 1 and 7 years. At the age of 7 years, children were evaluated for allergic sensitization and asthma based on symptom history, spirometry, exhaled nitric oxide, and airway reversibility. A questionnaire was administered to the parent regarding the childs asthma symptoms and other potential cofactors. RESULTS At the age of 7 years, 31 of 176 children (18%) were found to be asthmatic. Children living in a high ERMI value (≥5.2) home at 1 year of age had more than twice the risk of developing asthma than those in low ERMI value homes (<5.2) (adjusted odds ratio [aOR], 2.6; 95% confidence interval [CI], 1.10-6.26). Of the other covariates, only parental asthma (aOR, 4.0; 95% CI, 1.69-9.62) and allergic sensitization to house dust mite (aOR, 4.1; 95% CI, 1.55-11.07) were risk factors for asthma development. In contrast, air-conditioning at home reduced the risk of asthma development (aOR, 0.3; 95% CI, 0.14-0.83). A high ERMI value at 7 years of age was not associated with asthma at 7 years of age. CONCLUSIONS Early exposure to molds as measured by ERMI at 1 year of age, but not 7 years of age, significantly increased the risk for asthma at 7 years of age.

House dust (1-3)-β-D-glucan and wheezing in infants

Background:  (1–3)‐β‐d‐glucan is a fungal cell wall component, suspected to cause respiratory symptoms in adults. However, very little is known on the possible health effects of (1–3)‐β‐d‐glucan during infancy. We examined the association between (1–3)‐β‐d‐glucan exposure and the prevalence of allergen sensitization and wheezing during the first year of life in a birth cohort of 574 infants born to atopic parents. Endotoxin exposure was included as a possible confounder.

Concentration gradient patterns of aerosol particles near interstate highways in the Greater Cincinnati airshed

The objective of this study was to determine if there is an exposure gradient in particulate matter concentrations for people living near interstate highways, and to determine how far from the highway the gradient extends. Air samples were collected in a residential area of Greater Cincinnati in the vicinity of two major highways. The measurements were conducted at different distances from the highways by using ultrafine particle counters (measurement range: 0.02-1 microm), optical particle counters (0.3-20 microm), and PM2.5 Harvard Impactors (0.02-2.5 microm). The collected PM2.5 samples were analyzed for mass concentration, for elemental and organic carbon, and for elemental concentrations. The results show that the aerosol concentration gradient was most clearly seen in the particle number concentration measured by the ultrafine particle counters. The concentration of ultrafine particles decreased to half between the sampling points located at 50 m and 150 m downwind from the highway. Additionally, elemental analysis revealed a gradient in sulfur concentrations up to 400 m from the highway in a residential area that does not have major nearby industrial sources. This gradient was qualitatively attributed to the sulfate particle emissions from diesel engine exhausts, and was supported by the concentration data on several key elements indicative of traffic sources (road dust and diesel exhaust). As different particulate components gave different profiles of the diesel exposure gradient, these results indicate that no single element or component of diesel exhaust can be used as a surrogate for diesel exposure, but more comprehensive signature analysis is needed. This characterization is crucial especially when the exposure data are to be used in epidemiological studies.

Exposure to Traffic-related Particles and Endotoxin during Infancy Is Associated with Wheezing at Age 3 Years

RATIONALE Murine models demonstrate a synergistic production of reactive oxygen species on coexposure to diesel exhaust particles and endotoxin. OBJECTIVES It was hypothesized that coexposure to traffic-related particles and endotoxin would have an additive effect on persistent wheezing during early childhood. METHODS Persistent wheezing at age 36 months was assessed in the Cincinnati Childhood Allergy and Air Pollution Study, a high-risk birth cohort. A time-weighted average exposure to traffic-related particles was determined by applying a land-use regression model to the homes, day cares, and other locations where children spent time from birth through age 36 months. Indoor levels of endotoxin were measured from dust samples collected before age 12 months. The relationship between dichotomized (or=75th percentile) traffic-related particle and endotoxin exposure and persistent wheezing, controlling for potential covariates, was examined. MEASUREMENTS AND MAIN RESULTS Persistent wheezing at age 36 months was significantly associated with exposure to increased levels of traffic-related particles before age 12 months (OR = 1.75; 95% confidence interval, 1.07-2.87). Coexposure to endotoxin had a synergistic effect with traffic exposure on persistent wheeze (OR = 5.85; 95% confidence interval, 1.89-18.13) after adjustment for significant covariates. CONCLUSIONS The association between traffic-related particle exposure and persistent wheezing at age 36 months is modified by exposure to endotoxin. This finding supports prior toxicological studies demonstrating a synergistic production of reactive oxygen species after coexposure to diesel exhaust particles and endotoxin. The effect of early versus later exposure to traffic-related particles, however, remains to be studied because of the high correlation between exposure throughout the first 3 years of life.

Environmental risk factors of rhinitis in early infancy

Previous studies of allergic rhinitis in children have not documented the environmental risk factors for infants at age one. We examined the relationship of environmental tobacco smoke (ETS) and visible mold exposures on the development of allergic rhinitis, rhinitis and upper respiratory infection (URI) in a birth cohort where at least one parent was skin prick test (SPT) positive. ETS exposure and upper respiratory symptoms were obtained by questionnaires. Visible mold was classified as none, low or high during home visit. Infants had a SPT at age one. After adjustment for potential confounders, exposure to >20 cigarettes per day was associated with an increased risk of developing allergic rhinitis at age one [odds ratio (OR) = 2.7; 95% CI 1.04–6.8] and rhinitis symptoms during the first year (OR = 1.9; 95% CI 1.1–3.2). Infants with low (OR = 1.5; 95% CI 1.1–2.3) or high (OR = 5.1; 95% CI 2.2–12.1) levels of visible mold in their homes were more likely to have more frequent URI during the first year. Older siblings were protective for development of both rhinitis symptoms and allergic rhinitis. This study suggests that ETS exposure, rather than visible mold, is associated with rhinitis and allergic rhinitis in infants. The analysis also suggests that mold may be a stronger risk factor for URI that ETS.

Mold exposure during infancy as a predictor of potential asthma development

BACKGROUND Exposure to mold has been associated with exacerbation of asthma symptoms in children. OBJECTIVE To report how the presence of visible mold and exposure to (1-3)-beta-D-glucan in infancy affects the risk of asthma at the age of 3 years as defined by an Asthma Predictive Index (API). METHODS Visible mold was evaluated by means of home inspection. (1-3)-beta-D-glucan levels were measured in settled dust. Children were considered to be at high risk for asthma at later ages if they reported recurrent wheezing at the age of 3 years and met at least 1 of 3 major or 2 of 3 minor API criteria. RESULTS Children aged 3 years with high visible mold in the home during infancy were 7 times more likely to have a positive API than were those with no visible mold (adjusted odds ratio [aOR], 7.1; 95% confidence interval [CI], 2.2-12.6). In contrast, at low (1-3)-beta-D-glucan levels (< 22 microg/g), children were at increased risk of a positive API (aOR, 3.4; 95% CI, 0.5-23.5), whereas those with high (1-3)-beta-D-glucan levels (> 133 microg/g) were at decreased risk (aOR, 0.6; 95% CI, 0.2-1.6). Of the other covariates, mothers smoking was the strongest significant risk factor for the future development of asthma based on a positive API (aOR, 4.4; 95% CI, 1.7-11.6). CONCLUSIONS The presence of high visible mold and mothers smoking during infancy were the strongest risk factors for a positive API at the age of 3 years, suggesting an increased risk of asthma. High (1-3)-beta-D-glucan exposure seems to have an opposite effect on API than does visible mold.

An epidemiological appraisal instrument – a tool for evaluation of epidemiological studies

In recent years, ergonomics practices have increasingly relied upon the knowledge derived from epidemiological studies. In this regard, there is limited research devoted to the exclusive evaluation of the methodological qualities of ergonomics epidemiological studies. The aim of this study was to develop and test a general purpose ‘epidemiological appraisal instrument’ (EAI) for evaluating the methodological quality of existing or new ergonomic epidemiological studies using a critical appraisal system rooted in epidemiological principles. A pilot EAI version was developed and tested by a team of epidemiologists/physicians/biostatisticians, with the team leader being both epidemiologist and ergonomist. The pilot version was further tested with regard to other raters with/without a background in epidemiology, biostatistics and ergonomics. A revised version was evaluated for criterion validity and reliability. An assessor with a basic background in epidemiology and biostatistics would be able to correctly respond on four out of five questions, provided that subject matter expertise is obtained on specific items. This may improve with the articles quality. Training may have an effect upon assessors with virtually no background in epidemiology/biostatistics, but with a background in ergonomics. In this latter case, the inter-rater degree of agreement is largely above 90% and assessors can resolve their differences in a subsequent round. The EAI proved to be a valid and reliable appraisal instrument that may be used in various applications, such as systematic reviews and meta-analyses.

Traffic-Related Air Pollution Exposure in the First Year of Life and Behavioral Scores at 7 Years of Age

Background: There is increasing concern about the potential effects of traffic-related air pollution (TRAP) on the developing brain. The impact of TRAP exposure on childhood behavior is not fully understood because of limited epidemiologic studies. Objective: We explored the association between early-life exposure to TRAP using a surrogate, elemental carbon attributed to traffic (ECAT), and attention deficit/hyperactivity disorder (ADHD) symptoms at 7 years of age. Methods: From the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS) birth cohort we collected data on exposure to ECAT during infancy and behavioral scores at 7 years of age. Children enrolled in CCAAPS had at least one atopic parent and a birth residence either < 400 m or > 1,500 m from a major highway. Children were followed from infancy through 7 years of age. ECAT exposure during the first year of life was estimated based on measurements from 27 air sampling sites and land use regression modeling. Parents completed the Behavioral Assessment System for Children, 2nd Edition, when the child was 7 years of age. ADHD-related symptoms were assessed using the Hyperactivity, Attention Problems, Aggression, Conduct Problems, and Atypicality subscales. Results: Exposure to the highest tertile of ECAT during the child’s first year of life was significantly associated with Hyperactivity T-scores in the “at risk” range at 7 years of age, after adjustment [adjusted odds ratio (aOR) = 1.7; 95% CI: 1.0, 2.7]. Stratification by maternal education revealed a stronger association in children whose mothers had higher education (aOR = 2.3; 95% CI: 1.3, 4.1). Conclusions: ECAT exposure during infancy was associated with higher Hyperactivity scores in children; this association was limited to children whose mothers had more than a high school education.