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| Name | Class |
|---|---|
| State University of New York at Buffalo | OTHER |
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An epidemic of chronic kidney disease is occurring in laborers who undertake physical work outdoors in hot conditions. The reason for this is unknown, but may be related to kidney dysfunction caused by increases in body temperature and dehydration. The current heat stress recommendations for workers were not developed with regards for kidney health. The purpose of this study is to determine if the current recommendations protect against kidney dysfunction.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Fixed Work Rate | Experimental | Participants will walk on a treadmill at 3 mph and the grade will be adjusted to elicit 430 W of metabolic heat production (the most common work intensity). This study will systematically examine the NIOSH recommendations for prescribing work-to-rest ratios with increasing environmental heat stress (defined as Wet Bulb Globe Temperature, WBGT) at this fixed rate of metabolic heat production on kidney function. |
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| Fixed work-to-rest ratio | Experimental | This study will systematically examine the NIOSH recommendations on changes in kidney function when the work-to-rest ratio is fixed at 30 min per hour (the most commonly prescribed work-to-rest ratio), but the rate of metabolic heat production and environmental heat stress differs (Figure 2). As described in Study 1, the appropriate rate of metabolic heat production will be elicited by having participants walk on a treadmill at 3 mph and the grade will be adjusted accordingly. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| 23.0°C WBGT - Fixed Work Rate | Other | For four hours, participants will walk on a treadmill to elicit 430 W of metabolic heat production in the following conditions: 23.0°C WBGT (29°C, 46% relative humidity) @ 60 min exercise per hour |
| Measure | Description | Time Frame |
|---|---|---|
| Peak urinary [IGFBP7•TIMP-2] | Kidney injury marker | through study completion, up to 20 weeks |
| Measure | Description | Time Frame |
|---|---|---|
| Urinary NGAL | Kidney injury marker | through study completion, up to 20 weeks |
| Urinary IGFBP7 | Kidney injury marker | through study completion, up to 20 weeks |
| Measure | Description | Time Frame |
|---|---|---|
| Core body temperature | Heat strain variable | through study completion, up to 20 weeks |
| Mean skin temperature | Heat strain variable | through study completion, up to 20 weeks |
Inclusion Criteria:
Exclusion Criteria:
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| School of Public Health | Bloomington | Indiana | 47405-7109 | United States |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 40914830 | Derived | Hess HW, Hite MJ, Heikkinen ME, Tarr ML, Tourula E, Johnson BD, Hostler D, Schlader ZJ. Critical Assessment of the Recommended Alert Limit Curves for Occupational Heat Exposure. Am J Ind Med. 2025 Nov;68(11):1004-1012. doi: 10.1002/ajim.70022. Epub 2025 Sep 7. | |
| 37907448 | Derived | Hess HW, Baker TB, Tarr ML, Zoh RS, Johnson BD, Hostler D, Schlader ZJ. Occupational Heat Stress Recommendation Compliance Attenuates AKI Risk Compared with a Work-Rest Ratio-Matched, Positive Control Scenario. Kidney360. 2023 Dec 1;4(12):1752-1756. doi: 10.34067/KID.0000000000000288. Epub 2023 Nov 1. |
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This study will systematically examine the NIOSH recommendations for prescribing work-to-rest ratios during occupational heat stress on kidney function.
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The participant will not be directly informed of the experimental conditions and will be blinded to the hypotheses.
The outcomes assessor will be blinded to the experimental conditions when analyzing the data.
| 25.5°C WBGT - Fixed Work Rate | Other | For four hours, participants will walk on a treadmill to elicit 430 W of metabolic heat production in the following conditions: 25.5°C WBGT (31°C, 52% relative humidity) @ 45 min exercise per hour |
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| 27.5°C WBGT - Fixed Work Rate | Other | For four hours, participants will walk on a treadmill to elicit 430 W of metabolic heat production in the following conditions: 27.5°C WBGT (33°C, 53% relative humidity) @ 30 min exercise per hour |
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| 28.5°C WBGT - Fixed Work Rate | Other | For four hours, participants will walk on a treadmill to elicit 430 W of metabolic heat production in the following conditions: 28.5°C WBGT (34°C, 54% relative humidity) @ 15 min exercise per hour |
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| 35.5°C WBGT - Fixed Work Rate | Other | For four hours, participants will walk on a treadmill to elicit 430 W of metabolic heat production in the following conditions: 35.5°C WBGT (40°C, 65% relative humidity) @ 15 min exercise per hour |
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| 26.0°C WBGT - Fixed work-to-rest ratio | Other | For four hours, participants will walk on a treadmill at differing levels of metabolic heat production and environmental conditions (noted below), but at a fixed work-rest ratio of 30 minutes per hour. 26.0°C WBGT (31°C, 55% relative humidity) @ 530 W metabolic heat production |
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| 30.5°C WBGT - Fixed work-to-rest ratio | Other | For four hours, participants will walk on a treadmill at differing levels of metabolic heat production and environmental conditions (noted below), but at a fixed work-rest ratio of 30 minutes per hour. 30.5°C WBGT (36°C, 55% relative humidity) @ 230 W metabolic heat production |
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| 30.5°C WBGT - Fixed work-to-rest ratio (high intensity) | Other | For four hours, participants will walk on a treadmill at differing levels of metabolic heat production and environmental conditions (noted below), but at a fixed work-rest ratio of 30 minutes per hour. 30.5°C WBGT (36°C, 55% relative humidity) @ 530 W metabolic heat production |
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| Urinary TIMP-2 | Kidney injury marker | through study completion, up to 20 weeks |
| Urinary IL-18 | Kidney injury marker | through study completion, up to 20 weeks |
| Urinary L-FABP | Kidney injury marker | through study completion, up to 20 weeks |
| Renal artery blood velocity | Index of kidney blood flow | through study completion, up to 20 weeks |
| Segmental artery blood velocity | Index of kidney blood flow | through study completion, up to 20 weeks |
| Oxygen uptake | Heat strain variable | through study completion, up to 20 weeks |
| Heart rate | Heat strain variable | through study completion, up to 20 weeks |
| Blood pressure | Heat strain variable | through study completion, up to 20 weeks |
| Whole-body sweat rate | Hydration and heat strain variable | through study completion, up to 20 weeks |
| Percentage change in body weight | Hydration status variable | through study completion, up to 20 weeks |
| Plasma osmolality | Hydration status variable | through study completion, up to 20 weeks |
| Urine osmolality | Hydration status variable | through study completion, up to 20 weeks |
| Blood and plasma volume | Hydration status variable | through study completion, up to 20 weeks |
| Urine specific gravity | Hydration status variable | through study completion, up to 20 weeks |
| Plasma copeptin | Hydration status variable | through study completion, up to 20 weeks |
| Creatinine clearance | Kidney function variable | through study completion, up to 20 weeks |
| Fractional excretion of electrolytes | Kidney function variable | through study completion, up to 20 weeks |
| Free water clearance | Kidney function variable | through study completion, up to 20 weeks |
| Serum uric acid | Kidney function variable | through study completion, up to 20 weeks |
| Urinary uric acid | Kidney function variable | through study completion, up to 20 weeks |
| 36211944 | Derived | Hess HW, Tarr ML, Baker TB, Hostler D, Schlader ZJ. Ad libitum drinking prevents dehydration during physical work in the heat when adhering to occupational heat stress recommendations. Temperature (Austin). 2022 Jul 20;9(3):292-302. doi: 10.1080/23328940.2022.2094160. eCollection 2022. |
| ID | Term |
|---|---|
| D000084462 | Hyperthermia |
| D003681 | Dehydration |
| ID | Term |
|---|---|
| D001832 | Body Temperature Changes |
| D012816 | Signs and Symptoms |
| D013568 | Pathological Conditions, Signs and Symptoms |
| D018882 | Heat Stress Disorders |
| D014947 | Wounds and Injuries |
| D014883 | Water-Electrolyte Imbalance |
| D008659 | Metabolic Diseases |
| D009750 | Nutritional and Metabolic Diseases |
| D010335 | Pathologic Processes |
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