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Background: Roofers are at increased risk for various malignancies and their occupational exposures to polycyclic aromatic hydrocarbons (PAHs) have been considered as important risk factors. The overall goal of this project was to investigate the usefulness of phosphorylated histone H2AX (γH2AX) as a short-term biomarker of DNA damage among roofers., Methods: Blood, urine, and dermal wipe samples were collected from 20 roofers who work with hot asphalt before and after 6 h of work on Monday and Thursday of the same week (4 sampling periods). Particle-bound and gas-phase PAHs were collected using personal monitors during work hours. γH2AX was quantified in peripheral lymphocytes using flow cytometry and 8-hydroxy-2-deoxyguanosine (8-OHdG) was assessed in urine using ELISA. General linear mixed models were used to evaluate associations between DNA damage and possible predictors (such as sampling period, exposure levels, work- and life-style factors). Differences in mean biomarker and DNA damage levels were tested via ANOVA contrasts., Results: Exposure measurements did not show an association with any of the urinary biomarkers or the measures of DNA damage. Naphthalene was the most abundant PAH in gas-phase, while benzo(e)pyrene was the most abundant particle-bound PAH. Post-shift levels of γH2AX and 8-OHdG were higher on both study days, when compared to pre-shift levels. Cigarette smoking was a predictor of γH2AX and urinary creatinine was a predictor of urinary 8-OHdG. Between-subject variance to total variance ratio was 35.3 % for γH2ax and 4.8 % for 8-OHdG., Conclusion: γH2AX is a promising biomarker of DNA damage in occupational epidemiology studies. It has a lower within-subject variation than urinary 8-OHdG and can easily be detected in large scale groups. Future studies that explore the kinetics of H2AX phosphorylation in relation to chemical exposures may reveal the transient and persistent nature of this sensitive biomarker of early DNA damage.

To aid in the process of characterizing corn dust exposures on farms and in elevators in northeastern Colorado, several parameters were examined. Total dust and respirable dust samples were collected and evaluated. Potentially dangerous dust components evaluated were respirable silica, endotoxin, and mycotoxin levels. Many of the total dust samples (58%) would have exceeded 8-hour time-weighted average (TWA) had sampling been conducted for 8 hours; on farms the operation takes between two and four hours. The same statement may be made for respirable dust samples collected for this project. Nearly 33 percent of the respirable dust samples collected would have exceeded the Occupational Safety and Health Administration (OSHA) TWA had sampling been conducted over an 8-hour period. Respirable silica standards were exceeded at 25 percent of the sampling locations. Presence of mycotoxins at all sites was confirmed by the use of ELISA kits. The most significant finding of this study was high levels of endotoxin at several of the sampling sites. Eighty-five percent of the sampling locations had endotoxin levels above 500 EU/m3. One location, Farm 4, had endotoxin levels of above 1.7 million EU/m3.

Acute cross-shift respiratory changes were evaluated for workers at 25 farms in northeastern Colorado during the summer of 1994 wheat harvest. Information on workers' respiratory health, past occupational exposures, and smoking status was obtained. Each worker was asked to rank eight acute symptoms before he or she began harvest work for the day. Spirometry was also performed before work began. Each participant wore a high-flow personal air sampling pump for the full shift. At the end of the workshift, spirometry and ranking of the eight acute symptoms were conducted again. Total dust exposure was determined gravimetrically. Total endotoxin was measured by the Limulus amoebocyte lysate (LAL) assay. The 98 harvest workers included in the study ranged in age from 18 to 80. Ten percent of the workers had moderate airway obstruction, as indicated by the pre-shift spirometry test results. Fifty percent of the workers were current or ex-smokers. Despite an unusually poor harvest, total dust exposures ranged from 0.09 to 15.33 mg/m3 (geometric mean 0.83 mg/m3), with 8 percent of workers exposed above the American Conference of Government Industrial Hygienists (ACGIH) threshold limit value (TLV) of 4 mg/m3. Total endotoxin exposures ranged from 4.4 to 744.4 EU/m3 (geometric mean 54.2 EU/m3), with 33 percent of workers exposed above 90 EU/m3, the level suggested as a threshold for acute mucous membrane irritation and pulmonary change among cotton workers. Sixty percent of workers experienced a cross-shift change in at least one respiratory symptom. The respiratory index (sum of cross-shift changes in the eight acute respiratory symptoms) was significantly correlated with both total dust and endotoxin exposure. Cross-shift changes in the spirometric variables were associated with smoking status, age, presence of airway obstruction, and history of chronic respiratory symptoms, but not with dust or endotoxin exposure. Peak expiratory flow rate was found to decrease over the workshift in a manner similar to that experienced by cotton workers.

The study purpose was to determine whether group intervention or an individual self help program proved to be more effective at lowering heart disease risk factors among employees in different worksites. Eight worksites and 502 employees in the Denver metropolitan area were selected for the project, with four randomized to Usual Care and four to the Special Intervention. Most worksites had < 200 employees. Employees were randomly assigned to either a control group receiving usual nutrition education or one of two special intervention groups in which employees selected to attend group nutrition education classes or complete an individual self paced nutrition education program. Results indicated that offering a choice of methods for the special nutrition education intervention was valuable, and both approaches modified behavior and certain physiological outcomes. Results suggested that enhanced nutrition education efforts in worksites may be effective and will realize greater benefits than a pamphlet or brief discussion following a worksite screening.