Tracey Armitage

Particulate matter, endotoxin, and worker respiratory health on large Californian dairies

Objective: To assess respiratory exposures and lung function in a cross-sectional study of California dairy workers. Methods: Exposure of 205 dairy and 45 control (vegetable processing) workers to particulate matter and endotoxin was monitored. Pre- and postshift spirometry and interviews were conducted. Results: Geometric mean inhalable and PM2.5 concentrations were 812 and 35.3 &mgr;g/m3 versus 481.9 and 19.6 &mgr;g/m3, respectively, for dairy and control workers. Endotoxin concentrations were 329 EU/m3 or 1122 pmol/m3 and 13.5 EU/m3 or 110 pmol/m3, respectively, for dairy and control workers. In a mixed-effects model, forced vital capacity decreased across a work shift by 24.5 mL (95% confidence interval, −44.7 to −4.3; P = 0.018) with log10 (total endotoxin) and by 22.0 mL (95% confidence interval, −43.2 to −0.08; P = 0.042) per hour worked. Conclusions: Modern California dairy endotoxin exposures and shift length were associated with a mild acute decrease in forced vital capacity.

Heat strain, volume depletion and kidney function in California agricultural workers

Background Agricultural work can expose workers to increased risk of heat strain and volume depletion due to repeated exposures to high ambient temperatures, arduous physical exertion and limited rehydration. These risk factors may result in acute kidney injury (AKI). Methods We estimated AKI cumulative incidence in a convenience sample of 283 agricultural workers based on elevations of serum creatinine between preshift and postshift blood samples. Heat strain was assessed based on changes in core body temperature and heart rate. Volume depletion was assessed using changes in body mass over the work shift. Logistic regression models were used to estimate the associations of AKI with traditional risk factors (age, diabetes, hypertension and history of kidney disease) as well as with occupational risk factors (years in farm work, method of payment and farm task). Results 35 participants were characterised with incident AKI over the course of a work shift (12.3%). Workers who experienced heat strain had increased adjusted odds of AKI (1.34, 95% CI 1.04 to 1.74). Piece rate work was associated with 4.24 odds of AKI (95% CI 1.56 to 11.52). Females paid by the piece had 102.81 adjusted odds of AKI (95% CI 7.32 to 1443.20). Discussion Heat strain and piece rate work are associated with incident AKI after a single shift of agricultural work, though gender differences exist. Modifications to payment structures may help prevent AKI.

Cage Versus Noncage Laying-Hen Housings: Respiratory Exposures

ABSTRACT The objective of this study was to compare the personal respiratory exposures of poultry workers in three different types of layer housing under commercial production conditions. Workers were randomly assigned to each of conventional cage, enriched cage, and aviary barns in a crossover repeated-measures design for three observation periods over the hens’ lifetime. Inhalable and fine particulate matter (PM) and endotoxin in both size fractions were assessed by personal and area samplers over the work shift. Concentrations of inhalable PM, PM2.5 (PM with an aerodynamic diameter <2.5 μm), and endotoxin in both size fractions were higher in aviary than either the conventional or enriched barns. Geometric means (95% confidence intervals [CIs]) of inhalable PM and endotoxin for the aviary, conventional, and enriched barns were 8.9 (6.8–11.5) mg/m3 and 7517.9 (5403.2–10,460.2) EU/m3, 3.7 (2.8–4.8) mg/m3 and 1655.7 (1144.6–2395.2) EU/m3, 2.4 (1.8–3.3) mg/m3 and 1404.8 (983.3–2007.0) EU/m3, respectively. Area samplers recorded a lower mean inhalable PM concentration and higher PM2.5 concentration than personal samplers. Ammonia concentrations were low throughout three monitoring seasons. These findings show that the aviary barns pose higher respiratory exposures to poultry workers than either conventional or enriched barns.

Cage Versus Noncage Laying-Hen Housings: Worker Respiratory Health

ABSTRACT The objective of this study was to compare respiratory health of poultry workers in conventional cage, enriched cage and aviary layer housing on a single commercial facility, motivated by changing requirements for humane housing of hens. Three workers were randomly assigned daily, one to each of conventional cage, enriched cage, and aviary housing in a crossover repeated-measures design for three observation periods (for a total of 123 worker-days, eight different workers). Workers’ exposure to particles were assessed (Arteaga et al. J Agromedicine. 2015;20:this issue) and spirometry, exhaled nitric oxide, respiratory symptoms, and questionnaires were conducted pre- and post-shift. Personal exposures to particles and endotoxin were significantly higher in the aviary than the other housings (Arteaga et al., 2015). The use of respiratory protection was high; the median usage was 70% of the shift. Mixed-effects multivariate regression models of respiratory cross-shift changes were marginally significant, but the aviary system consistently posted the highest decrements for forced expiratory volume in 1 and 6 seconds (FEV1 and FEV6) compared with the enriched or conventional housing. The adjusted mean difference in FEV1 aviary − enriched cage housing was −47 mL/s, 95% confidence interval (CI): (−99 to 4.9), P = .07. Similarly, for FEV6, aviary − conventional housing adjusted mean difference was −52.9 mL/6 s, 95% CI: (−108 to 2.4), P = .06. Workers adopting greater than median use of respiratory protection were less likely to exhibit negative cross-shift pulmonary function changes. Although aviary housing exposed workers to significantly higher respiratory exposures, cross-shift pulmonary function changes did not differ significantly between houses. Higher levels of mask use were protective; poultry workers should wear respiratory protection as appropriate to avoid health decrements.

Mortality in the California Farmer Health Study Cohort

ABSTRACT Western agriculture, in comparison with Midwestern and Eastern, is more diverse, with a drier climate, mild winters, and different exposures. This randomly selected cohort of 1947 Californian farmers confirmed the usual finding: a lower mortality rate than general population (by 50%). A low smoking prevalence and healthy worker effect are likely contributors. Although farmers were more likely to die from injuries and skin cancer, death was less likely from Alzheimers and cerebrovascular diseases. Within the cohort, disability and persistent wheeze were associated with increased mortality. The 200 deaths were insufficient to determine the significance of rare diseases.

Physical activity and common tasks of California farm workers: California Heat Illness Prevention Study (CHIPS)

Abstract Farm workers are at risk of heat related illness (HRI), but their work rates that contribute to HRI have not been objectively assessed. The CHIPS study collected accelerometer data and characterized the physical activity of major farm tasks. Demographic information, work characteristics, and accelerometer data were collected from 575 farm workers in California. Each participating worker contributed measurements over one work shift. An Actical accelerometer was attached securely to a belt worn at the hip. Data were collected at one-minute intervals throughout the work shift. A total of 13 major work-task categories were defined. The mean physical activity counts per minute (cpm) and percentage of the shift spent at moderate and/or vigorous levels of activity were described for each task. Multiple linear regression models were constructed to determine the worker and environmental characteristics contributing to the physical activity level. Mean levels of physical activity ranged from 700 cpm (workers who carry produce) to a low of 150 cpm “ground pruners” who tend low-level plants, with an overall mean of 345 cpm or “light” activity (2 to ≤3 metabolic equivalents). The environmental temperature was the major factor associated with physical activity. A 10°C increase in the median temperature reduced the mean cpm by 135 (95% CI = 87, 193). Age and the tasks of sorting, ground pruning, and harvesting low-level crops were also negatively and independently associated with mean cpm. Incentivized (piece rate) pay, multi-task work, and irrigator work were positively associated with cpm. An interaction was found between piece rate and sex. Men’s activity significantly increased (p < 0.001) by a mean of 95 cpm, (95% CI = 38.3, 150.7) if they were paid by the piece, but there was a non-significant association with women’s activity level. Workers conducting multiple tasks, irrigators, men, and those earning incentivized (piece rate) pay had higher adjusted mean physical activity levels and are likely at increased risk of heat-related illness on hot days.

0229 Risk of heat related illness in latino agricultural workers: core body temperature and work task

Introduction Environmental heat and work-rate are risk factors for Heat Related Illness (HRI). Work-rate by task and core temperature have not been quantified in California farmworkers. Methods Farmworkers were monitored for one work-shift each in the summers of 2014–2015. Individuals’ core temperature was assessed throughout the shift using an ingestible sensor, a 3 min moving average computed and maximum temperature identified. Accelerometers were worn, and NHANES criteria used to classify counts per minute (cpm) into sedentary, low, moderate and vigorous activity. Daily work-rate was categorised by the number of minutes spent in moderate and/or vigorous activity (<30, 30 to 90,>90). Questionnaires administered in Spanish collected occupational tasks conducted and self-rated environmental heat exposure. Results 499 Latina/o farmworkers performed only one task on their shift. The mean activity in cpm was highest for tree/vine harvesters 445 (SD 225) and lowest for produce sorters 193 (SD 167). 22 workers recorded a maximal core temperature >38.5°C, a criteria for heat stress in acclimatised workers. In a multivariable logistic regression high body temperature was associated with both the number of minutes working at a moderate/vigorous rate and self-rated environmental heat; OR and (95% CI) for ≥90 v<90 min high activity 3.6 (1.5–8.5). Irrigators were the only classification with statistically significant association with elevated core temperature; OR and (95% CI) 3.7 (1.4–9.6). Conclusion Farmworkers, who exceed 90 min a day in moderate/vigorous activity and/or irrigators, are at higher risk of HRI. These workers may need closer monitoring for their safety.

0227 Risk of heat related illness: differences between male and female farmworkers with respect to hydration practices

Introduction Dehydration is a major risk factor for Heat Related Illness (HRI) in farmworkers. Methods 587 acclimatised Latina/o farmworkers were monitored once each, in the hot, dry, California Central Valley over the summers of 2014–2015. Weight was recorded before and after the shift in a minimum level of clothing to assess change in hydration. To assess activity, accelerometers were worn, and questionnaires were administered in Spanish to collect occupational characteristics. Results 66.2% of the participants were male; both sexes had a mean age 38.7 years. Men drank more, either total or just water (adjusted for height) than women (mean volumes 112 v 77oz, or 97 v 67 oz, PVal <0.001 for both). However men were more likely to lose ≥1.5% of their body weight: 64 (16.5%) v 6 (3.0%) women PVal <0.0001. Shift lengths were similar, but both total and mean activity levels were higher in males 2 02 000 v 1 33 000 and 391 v 255 counts per minute, respectively PVal <0.0001 for both. Being male, working any type of piece rate and higher mean activity were all independently associated with weight loss over the shift in a multivariable linear regression model. Parameter and (95% CI) respectively: - 0.31 (- 0.43 to - 0.19), 0.18 (0.05–0.309), and mean cpm/100 0.022 (0.001–0.045). Conclusion Male Latino farmworkers are more at risk of dehydration especially those who work high activity tasks or any form of piece rate. Employers should focus special attention on the safety of these workers.

Recruitment, Methods, and Descriptive Results of a Physiologic Assessment of Latino Farmworkers: The California Heat Illness Prevention Study

Objective: The California heat illness prevention study (CHIPS) devised methodology and collected physiological data to assess heat related illness (HRI) risk in Latino farmworkers. Methods: Bilingual researchers monitored HRI across a workshift, recording core temperature, work rate (metabolic equivalents [METs]), and heart rate at minute intervals. Hydration status was assessed by changes in weight and blood osmolality. Personal data loggers and a weather station measured exposure to heat. Interviewer administered questionnaires were used to collect demographic and occupational information. Results: California farmworkers (n = 588) were assessed. Acceptable quality data was obtained from 80% of participants (core temperature) to 100% of participants (weight change). Workers (8.3%) experienced a core body temperature more than or equal to 38.5 °C and 11.8% experienced dehydration (lost more than 1.5% of body weight). Conclusions: Methodology is presented for the first comprehensive physiological assessment of HRI risk in California farmworkers.

Are respiratory decrements associated with exposure to particles including endotoxins on large California dairies

Objectives To determine whether exposure to particulate matter (PM) including endotoxins on large California dairies is associated with decreased cross-shift respiratory function. Methods Male workers at 13 dairies and one control facility wore personal air samplers collecting total suspended particles (TSP) or PM2.5 over their shift. Pre- and post-shift questionnaires and pulmonary function tests were also conducted. TSP endotoxins were assessed using recombinant Factor C and GC-MS. Associations between exposure to PM and cross-shift lung function changes were assessed by regression analysis using GLMs. Results Data from 205 dairy and 45 control facility workers were analysed. Exposure to either PM or endotoxin was significantly higher in dairy versus control workers (p<0.0001). Geometric mean dairy exposures were 793 and 35 µg/m3 for TSP and PM2.5; 326 EU/m3 and 0.45 picomoles/m3 for TSP endotoxin respectively. Across a shift, 29.3% and 15.6% of dairy and control workers respectively had ≥3% decrease in FEV1 while 29.6% and 13.3% of workers had similar decrements in FVC. Cross-shift pulmonary function outcomes were modelled against exposures and potential relevant factors such as smoking, age, shift length and dairy/control worker. PM2.5, TSP and endotoxin exposures were not significantly associated with changes in pulmonary function. Dairy versus control work was associated with cross-shift FEV1 regression estimates of -64 ml (p =0.02) and FVC estimates of -90 ml (p = 0.008). Conclusions Cross-shift decrements in pulmonary function were associated significantly with dairy work. However neither the concentration of PM nor endotoxin components in TSP were associated with these decrements.