Ad Libitum Drinking Prevents Dehydration During Physical Work in the Heat When Adhering to Occupational Heat Stress Recommendations

Details

• Personal Author:
  Baker TB ; Hess HW ; Hostler D ; Schlader ZJ ; Tarr ML
• Description:
  Government entities issue recommendations that aim to maintain core temperature below 38.0 degrees C and prevent dehydration [>2% body mass loss] in unacclimated workers exposed to heat. Hydration recommendations suggest drinking 237 mL of a cool sport drink every 15-20 min. This is based on the premise that ad libitum drinking results in dehydration due to inadequate fluid replacement, but this has never been examined in the background of recommendation compliant work in the heat. Therefore, we tested the hypothesis that ad libitum drinking results in >2% body mass loss during heat stress recommendation compliant work. Ten subjects completed four trials consisting of 4 hours of exposure to wet bulb globe temperatures (WBGT) of 24.1 +/- 0.3 degrees C (A), 26.6 +/- 0.2 degrees C (B), 28.5 +/- 0.2 degrees C (C), 29.3 +/- 0.6 degrees C (D). Subjects walked on a treadmill and work-rest ratios were prescribed as a function of WBGT [work:rest per hour - A: 60:0, B: 45:15, C: 30:30, D: 15:45] and were provided 237 mL of a cool sport drink every 15 min to drink ad libitum. Mean core temperature was higher in Trial A (37.8 +/- 0.4 degrees C; p = 0.03) and Trial B (37.6 +/- 0.3 degrees C; p = 0.01) versus Trial D (37.3 +/- 0.3 degrees C) but did not differ between the other trials (p ≥ 0.20). Body mass loss (A: -0.9 +/- 0.7%, B: -0.7 +/- 0.5%, C: -0.3 +/- 0.5%, D: -0.4 +/- 0.6%) was greater in Trial A compared to Trial D (p = 0.04) and was different from 2% body mass loss in all trials (p ≤ 0.01). Ad libitum drinking during recommendation compliant work in the heat rarely resulted in dehydration. [Description provided by NIOSH]
• Subjects:
  Heat Stress Disorders Hot Temperature Occupational Health Safety
• Keywords:
  Author Keywords: Dehydration Body Temperature Drinking Water Heat Exposure Heat Strain Heat Stress Hot Environments Hydration Hyperthermia Hypohydration Occupational Heat Stress Physiological Effects Recommendations

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• ISSN:
  2332-8940
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Indiana ; New York ; OSHA Region 2 ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  292-302
• Volume:
  9
• Issue:
  3
• NIOSHTIC Number:
  nn:20067877
• Citation:
  Temperature 2022 Jul; 9(3):292-302
• Contact Point Address:
  Zachary Schlader, Department of Kinesiology, School of Public Health, Indiana University, Bloomington, IN, USA
• Email:
  zschlade@indiana.edu
• Federal Fiscal Year:
  2022
• NORA Priority Area:
  Agriculture, Forestry and Fishing ; Construction
• Performing Organization:
  Indiana University, Bloomington
• Peer Reviewed:
  True
• Start Date:
  20190901
• Source Full Name:
  Temperature
• End Date:
  20240831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:59e607a0be79f9d1462e2821b4768ab71476c94823dc7f6d45b30ca25c596eb045e5457f5029311501c75a35ed060d7fce74e7fc58aef6c61b625bb84379d725
• Download URL:
  https://stacks.cdc.gov/view/cdc/230116/cdc_230116_DS1.pdf
• File Type:
  [PDF - 1.44 MB ]