Environmental Heat Stress and Physiological Heat Strain in Construction Workers During Work in the Summer

Construction workers are thirteen times more likely to die from heat-related illnesses compared to the general population. This elevaled risk results from both metabolic heat production due to the physical demands of construction work associated with high environmental heat stress. However, it is important to recognize that the magnitude of heat stress experienced varies across job types withing the construction industry reflecting the diversity of tasks performed. In addition, environmental heat stress can significantly vary for workers based on whether they operate in covered or uncovered work areas, creating varying levels of heat sttres, particularly during during summer months. Notably, despite these evident risks, no previous study has assessed thermal strain via core temperature (Tcore) in construction workers during summertime in the United States. PURPOSE: To measure environmental heat stress and physiological heat strain in construction workers during work in the summer. METHODS: Over three days, 32 construction workers (3 females) agreed to participate in this study. Participants were identified by both job type and working conditions, depending upon their description of tasks and if they worked in a covered or uncovered area. Heart rate, Tcore, rating of perceived exertion, and thermal comfort were measured during a typical work in the month of July. Additionally, hydration was assessed via pre and post-shift measurements of urine specific gravity and body weight. Heat index (HI) was calculated from dry bulb temperature and humidity continuous measurements in both covered and uncovered working environments. RESULTS: The highest observed peak HI during the 3 days of data collection was 34oC indicating low to moderate heat stress. Roofers were exposed to the peak HI compared to other job types, but no significant differences were observed between covered and uncovered areas. Metabolic rate calculated from HR and Tcore was higher in workers in uncovered areas compared to unovered, but not different among job types. 43% of the participants had Tcore exceeding 38°C, whith 4% exceeding 38.5°C. The majority of participants experienced a dehydration level of approximately 1%. CONCLUSION: Construction workers experience significant heat strain, even under conditions of moderate heat stress. This heat strain varies due to job type, which is highly variable in construction workers, and specific working environment

Dietary Relationship with 24 h Urinary Iodine Concentrations of Young Adults in the Mountain West Region of the United States

Background: Iodine deficiency is not seen as a public health concern in the US. However certain subpopulations may be vulnerable due to inadequate dietary sources. The purpose of the present study was to determine the dietary habits that influence iodine status in young adult men and women, and to evaluate the relationship between iodine status and thyroid function. Methods: 111 participants (31.6 ± 0.8 years, 173.2 ± 1.0 cm, 74.9 ± 1.7 kg) provided 24 h urine samples and completed an iodine-specific Food Frequency Questionnaire (FFQ) for assessment of urinary iodine content (UIC) as a marker of iodine status and habitual iodine intake, respectively. Serum Thyroid Stimulating Hormone (TSH) concentration was evaluated as a marker of thyroid function. Spearman correlational and regression analysis were performed to analyze the associations between iodine intake and iodine status, and iodine status and thyroid function. Results: 50.4% of participants had a 24 h UIC < 100 µg/L). Dairy (r = 0.391, p < 0.000) and egg intake (r = 0.192, p = 0.044) were the best predictors of UIC, accounting for 19.7% of the variance (p ≤ 0.0001). There was a significant correlation between UIC and serum TSH (r = 0.194, p < 0.05) but TSH did not vary by iodine status category (F = 1.087, p = 0.372). Discussion: Total dairy and egg intake were the primary predictors of estimated iodine intake, as well as UIC. Iodized salt use was not a significant predictor, raising questions about the reliability of iodized salt recall. These data will be useful in directing public health and clinical assessment efforts in the US and other countries

Body Composition, Anemia, and Kidney Function among Guatemalan Sugarcane Workers

Rates of anemia among agricultural workers, who are also at risk for kidney injury and chronic kidney disease of unknown cause (CKDu), are unknown. We evaluated body composition through the sum of three skinfolds among 203 male sugarcane cutters and assessed the relationship of variables related to nutrition, anemia (hemoglobin < 13 g/dL), and elevated hemoglobin A1c (HbA1c ≥ 5.7%) with estimated glomerular filtration rate (eGFR) using linear regression. Eleven percent of workers were at the level of essential body fat (2–5%). Anemia was present among 13% of workers, 70% of which were normochromic normocytic, a type of anemia suggesting potential underlying chronic disease. Anemia was more common among those with lower BMI and fat free mass. The prevalence of elevated HbA1c was 21%. A moderate negative correlation was found between hemoglobin and HbA1c (Pearson’s r = −0.32, p < 0.01) which suggests that HbA1c values should be interpreted with caution in populations that have high rates of anemia. Twelve percent of workers had reduced kidney function with an eGFR < 90 mL/min/1.73 m2. On average, the eGFR was 18 mL/min per 1.73 m2 lower [(95% CI:−24, −12), p < 0.01)] for those with anemia than those without, and 8 mL/min per 1.73 m2 lower among those with elevated HbA1c [(95% CI: −13, −2), p < 0.01]. Results will inform future studies examining the role of anemia in the evaluation of CKDu and interventions to improve nutrition for workers in low-resource settings