A modified physiological strain index for workplace-based assessment of heat strain experienced by agricultural workers.

BACKGROUND: As global temperatures rise, increasing numbers of individuals will work in hot environments. Interventions to protect their health are critical, as are reliable methods to measure the physiological strain experienced from heat exposure. The physiological strain index (PSI) is a measure of heat strain that relies on heart rate and core temperature but is challenging to calculate in a real-world occupational setting. METHODS: We modified the PSI for use in field settings where resting temperature and heart rate are not available and used the modified physiological strain index (mPSI) to describe risk factors for high heat strain (mPSI ≥ 7) experienced by agricultural workers in Florida during the summers of 2015 through 2017. mPSI was calculated for 221 workers, yielding 465 days of data. RESULTS: A higher heat index (ß = 0.185; 95% CI: 0.064, 0.307) and higher levels of physical activity at work (0.033; 95% CI: 0.017, 0.050) were associated with a higher maximum mPSI. More years worked in US agriculture (-0.041; 95% CI: -0.061, -0.020) were protective against a higher maximum mPSI. Out of 23 workdays that a participant experienced a maximum mPSI ≥ 7, 22 were also classified as strained by at least one other measure of high heat strain (core temperature [Tc] >38.5°C, sustained heart rate >(180 - age), and mean heart rate > 115 bpm). CONCLUSIONS: This study provides critical information on risk factors for elevated heat strain for agricultural workers and suggests a practical approach for using PSI in field-based settings.

Risk Factors for Reaching Core Body Temperature Thresholds in Florida Agricultural Workers.

BACKGROUND: There is a compelling need to identify agricultural workers at risk for heat related illness (HRI). METHODS: Data from Florida agricultural workers (N = 221) were collected over 3 summer workdays (2015 to 2017) to examine risk factors for exceeding NIOSH-recommended core temperature (Tc) thresholds (38 °C [Tc38] and 38.5 °C [Tc38.5]) using generalized linear mixed models. RESULTS: On an average workday, 49% of participants exceeded Tc38 and 10% exceeded Tc38.5. On average, participants first exceeded both thresholds early in the day; the Tc38 threshold mid-morning (10:38 AM), and Tc38.5 about a half hour later (11:10 AM). Risk factors associated with exceeding Tc38 included years working in US agriculture, body mass index, time performing moderate-to-vigorous physical activity, increasing heat index, and field crop work. CONCLUSIONS: The high prevalence of core temperatures exceeding recommended limits emphasizes the serious need for mandated HRI prevention programs for outdoor workers.

Elevated Core Temperature in Florida Fernery Workers: Results of a Pilot Study.

With expected increases in extreme weather, there may be a greater risk of injury from extreme heat in outdoor worker populations. To plan for future adaptation measures, studies are needed that can characterize workers' physiologic responses to heat in outdoor settings such as agriculture. The objective of this study was to characterize occupational heat exposure, key vulnerability factors (e.g., gender, energy expenditure), and physiologic heat stress response in a sample of fernery workers. Forty-three fernery workers over 86 workdays were examined regarding heat-related illness (HRI) during the summer months of 2012 and 2013. The key outcome measure was whether a participant's body core temperature (Tc) reached or exceeded 38.0°C (100.4ºF; Tc38). Participants' Tc exceeded 38.0°C on 49 (57%) of the workdays, with 30 of 40 participants reaching or exceeding Tc38 on at least one workday. Adjusting for sex, there was a 12% increase in the odds of Tc38 for every 100 kilocalories of energy expended (OR: 1.12; 95% Confidence Interval [CI]: [1.03, 1.21]). Adjusting for energy expenditure, females had 5 times greater odds of Tc38 compared with males (OR: 5.38; 95% CI: [1.03, 18.30]). These findings provide evidence of elevated Tc in Florida fernery workers, indicating an increased risk of occupational HRI, and the need for policy and interventions to address this health risk.

Lessons Learned from Data Collection as Health Screening in Underserved Farmworker Communities.

BACKGROUND: Girasoles is an academic-community partnership investigating heat-related illness (HRI) among farm-workers. An unexpected outcome is health screening and intervention for participants without access to health care. OBJECTIVES: We present a case of renal failure in a farmworker, detected during data collection, to illustrate how academic-community collaboration can result in clinical benefits for study participants. METHODS: Girasoles is examining physiologic responses to heat stress, associated vulnerability factors, and HRI symptoms. Data include blood pressure, fasting and non-fasting blood glucose, blood creatinine, blood urea nitrogen, and urine dipsticks. Participants with out-of-range findings are referred to local health care providers. RESULTS: During two summers, health screenings of 192 workers resulted in 71 referrals (37%) for conditions to be rechecked and treated. One of these referrals involved chronic renal failure requiring extensive follow-up by research team members. CONCLUSIONS: The case of renal failure illustrates the value of collaborative research as a health intervention with vulnerable populations.

Hydration Status, Kidney Function, and Kidney Injury in Florida Agricultural Workers.

OBJECTIVE: Recent findings suggest that laboring in hot occupational environments is related to kidney damage in agricultural workers. We examined hydration status and kidney function in 192 Florida agricultural workers. METHODS: Blood and urine samples were collected over 555 workdays during the summers of 2015 and 2016. Urine-specific gravity (USG), serum creatinine, and other kidney function markers were examined pre- and post-shift on each workday. Multivariable mixed modeling was used to examine the association of risk factors with hydration status and acute kidney injury (AKI). RESULTS: Approximately 53% of workers were dehydrated (USG ≥1.020) pre-shift and 81% post-shift; 33% of participants had AKI on at least one workday. The odds of AKI increased 47% for each 5-degree (°F) increase in heat index. CONCLUSION: A strikingly high prevalence of dehydration and AKI exists in Florida agricultural workers.

The Association Between Skin Rashes and Work Environment, Personal Protective Equipment, and Hygiene Practices Among Female Farmworkers.

The objective of this study was to assess work-related hygiene practices and the frequency and location of skin rashes due to cutaneous contact with crop-associated materials (e.g., pesticides) for female nursery and fernery workers in Central Florida. A cross-sectional, community-based participatory research study of 237 female nursery and fernery workers between the ages of 19 and 43 years with significant cutaneous contact with foliage crops was conducted using a self-report questionnaire and a skin rash chart assessment tool. Of the 237 farmworkers surveyed, 37.1% ( n = 88) reported a rash on at least one area of their bodies. Women who were pregnant during the study were 4.7 times more likely to report more than 30% total body surface area (TBSA) covered by rash compared with non-pregnant fernery workers ( p = .045; 95% confidence interval [CI] [1.04, 21.35]). Further research is needed to better understand the development of skin rashes among farmworkers, to generate effective prevention strategies.

Heat Exposure in Central Florida Fernery Workers: Results of a Feasibility Study.

OBJECTIVE: The objective of this study was to determine the feasibility of field-based biomonitoring of heat-related illness (HRI) phenomena in Florida farmworkers. The authors determined feasibility through participant interviews regarding acceptability, data capture, recruitment and retention, and observed barriers and challenges to implementation. METHODS: Study participants were employed in fernery operations in northeast Central Florida where ornamental ferns are grown and harvested in a seasonally high-heat environment. In this pilot, a total of 43 farmworkers participated during summers 2012 and 2013 and measurements included body core temperature, heart rate, energy expenditure, urine and blood osmolality, and self-reported HRI symptoms. RESULTS: Data capture was approximately 90%. Participants reported that the study methods were nonobtrusive to their work, and that they were comfortable with study measures. CONCLUSIONS: These results open possibilities for characterizing HRI utilizing physiologic biomonitoring in vulnerable occupational groups.

Novel Analytic Methods Needed for Real-Time Continuous Core Body Temperature Data.

Affordable measurement of core body temperature (Tc) in a continuous, real-time fashion is now possible. With this advance comes a new data analysis paradigm for occupational epidemiology. We characterize issues arising after obtaining Tc data over 188 workdays for 83 participating farmworkers, a population vulnerable to effects of rising temperatures due to climate change. We describe a novel approach to these data using smoothing and functional data analysis. This approach highlights different data aspects compared with describing Tc at a single time point or summaries of the time course into an indicator function (e.g., did Tc ever exceed 38 °C, the threshold limit value for occupational heat exposure). Participants working in ferneries had significantly higher Tc at some point during the workday compared with those working in nurseries, despite a shorter workday for fernery participants. Our results typify the challenges and opportunities in analyzing Big Data streams from real-time physiologic monitoring.

Pesticide risk perception and biomarkers of exposure in Florida female farmworkers.

OBJECTIVE: To compare workplace characteristics, workplace behaviors, and the health beliefs of female farmworkers of childbearing age with actual biomarkers of exposure to organophosphate pesticides and to the fungicide mancozeb. METHODS: Hispanic and Haitian farmworkers between the ages of 18 and 40 years working in nursery or fernery operations were recruited to participate in a cross-sectional survey, examining demographics, work practices, work-related hygiene, and pesticide exposure beliefs. Single-void (spot) urine samples were analyzed for organophosphate and ethylenethiourea metabolites. RESULTS: Women in nurseries worried less frequently about the effects of pesticides on their health than those in fernery operations. In summary, organophosphate and ethylenethiourea levels in nursery workers were significantly higher than levels in fernery workers and the control group. CONCLUSIONS: Results showed that perceived pesticide exposure did not correspond to actual metabolite levels within differing agricultural subpopulations.