Heat stress poses health risks for salt pan workers, study finds

The study outlined the need for workplace interventions to provide access to water, rests in shade, sanitation and education on the need to hydrate

August 17, 2023 11:19 pm | Updated August 18, 2023 10:53 am IST

Heat stress has a high physical cost

Heat stress has a high physical cost | Photo Credit: Getty Images/iStockphoto

A study conducted among salt pan workers in Tamil Nadu has highlighted the impact of heat stress. It found that nine of 10 salt pan workers had self-reported heat-strain symptoms, their average water intake was one litre during the workday and majority of them were exposed to high levels of heat stress, the study outlined the need for workplace interventions to provide access to water, rests in shade, sanitation and education on the need to hydrate.

The study - ‘Occupational Heat Stress and Kidney Health in Salt Pan Workers’ - conducted by a team led by Vidhya Venugopal, professor of Occupational and Environmental Health, Sri Ramachandra Institute of Higher Education and Research, looked at 352 workers in seven salt pans in Tamil Nadu - four in Marakkanam and three in Vedaranyam between 2017 and 2020. It was published in the Kidney International Reports.

During the study, the researchers evaluated the workload for different job roles and classified heat stress levels. Key indicators such as pre-and post-shift heart rates, core body temperatures, urine characteristics, sweat rates and kidney function parameters were measured.

It found that every participant had either a heavy or moderate workload, and close to 90% of workers were found to be working above the recommended limits of heat exposure. The wet-bulb globe temperature, a composite measure of environmental factors affecting human thermal comfort, consistently surpassed safe levels in the saltpans especially during summer months.

The majority of workers (93%) reported that they had experienced at least one of the self-reported heat strain systems - excessive sweating, thirst, dizziness, muscle cramps, headache, nausea/vomiting, fainting, or prickly heat/rashes. Dry mouth or severe thirst - signs of dehydration - was reported by 59% of the workers. About 77% of the workers reported at least one of these symptoms - changes in urine volume or colour, burning sensations when urinating, rashes and urinary tract infections (UTI).

The workers brought their own one-litre water bottle to sip throughout the day and had access to water for refilling bottles at work. But they found that the reported water consumption was low. About 23% of women stated that they would drink more water if they had improved toilet access.

One out of every five workers had taken sick leave owing to heat-related health difficulties in the last six months, while a third of workers said they did not finish their work on time because they were working in the heat.

What was worrying was the impact of heat stress on kidney health: the study revealed a prevalence of low estimated glomerular filtration rate (eGFR), a marker of kidney function, in seven percent of workers. Heat stress has been linked to various kidney-related issues including acute kidney injury, kidney stones, chronic kidney disease and UTI.

Dr. Venugopal, who is also a co-investigator of the UK NIHR Funded Global Health Research Centre, said: “We have compelling evidence that heat stress poses significant health risks for these workers. Urgent action is needed to implement adaptation strategies and improve healthcare, sanitation access and welfare facilities to protect vulnerable individuals.”


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