Rising temperatures threaten workers in Tamil Nadu's salt pans: Study

A recent study conducted in the coastal salt pans of Tamil Nadu, has revealed that rising global temperatures pose a serious occupational health risk to millions of workers. The research, carried out between 2017 and 2020, focused on the impact of heat stress on kidney function among non-agricultural workers.

Salt industry workers face severe heat stress

The study titled Occupational Heat Stress and Kidney Health in Salt Pan Workers, which was published on April 20, 2023, led by researchers at the Sri Ramchandra Institute of Higher Education and Research, Chennai, surveyed seven salt pans in Tamil Nadu. The absence of occupational exposures to pesticides and other toxicants in these areas allowed for a unique opportunity to assess the impact of heat stress alone.

The research focused on a wide age range of workers, from 18 to 85 years, with more than half having spent over 15 years in the salt industry. The majority of these workers were engaged in heavy manual tasks such as loading and unloading salt heaps.

Researchers evaluated the workload for various job roles and classified the levels of heat stress. They measured key indicators such as heart rates before and after shifts, core body temperatures, characteristics of urine, sweat rates, and parameters of kidney function.The wet bulb globe temperature (WBGT), a composite measure of environmental factors affecting human thermal comfort, consistently surpassed safe levels in the saltpans, particularly during summer months.

Alarmingly, the study found that close to 90 per cent of workers were found to be working above the recommended limits of heat exposure. International regulations advise implementing regular break periods under such circumstances, but none of the salt pans examined had such breaks in place.

The workers reported symptoms of heat strain, dehydration, and urinary tract infection symptoms, likely due to excessive sweating, lack of toilet access and limited water consumption during their shifts. Of particular concern is 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 7 per cent of workers.

High heat stress, dehydration among workers

The study revealed that a staggering 93% of workers reported experiencing at least one symptom of heat strain during the current season. These symptoms included excessive sweating, thirst, dizziness, muscle cramps, headache, nausea/vomiting, fainting, or prickly heat/rashes. Dehydration signs such as dry mouth or severe thirst were reported by 59% of the workers. Changes in urine volume or color, burning sensations when urinating, rashes, and urinary tract infections were widespread, with 77% of the workers reporting at least one of these symptoms.

Despite having access to water for refilling bottles at work, reported water consumption was low. About 23% of women stated that if they had improved toilet access, they would drink more. One out of every five workers had taken sick leave owing to heat-related health difficulties in the last six months. Moreover, a third of the workers said they did not finish their work on time because they were working in the heat, resulting in missed income.

Symptoms of dehydration were prevalent among workers, as were tiredness/weakness and other signs of heat strain. High USG levels observed before (10.1%) and after work (28%) and the average water intake of only 1 liter during the workday indicates a marked lack of rehydration.

The study suggests that the lack of access to drinkable water during the workday is not the only factor contributing to dehydration among workers. Workers also intentionally limit their fluid intake to avoid the need for urination. This behavior is particularly prevalent in Indian settings where proper sanitation facilities are lacking, especially for women. This self-imposed restriction on fluid intake, combined with working in high-temperature environments and excessive sweating, significantly increases the risk of dehydration.

Urgent action needed for heat-exposed workers

The researchers called for urgent action to implement adaptation strategies and improve health care, sanitation access and welfare facilities to protect vulnerable individuals. They warned that failure to address this issue will result in increased heat-related illnesses, particularly chronic kidney diseases, worsened by pre-existing medical conditions, and potentially devastating health consequences for workers around the world.

The study underscores the fact that these workers experience prolonged exposure to high temperatures without sufficient access to adaptation strategies such as shade, rehydration, and rest breaks. Many are hesitant to report symptoms of heat stress due to fear of job loss or retaliation. The risk is further magnified for undocumented workers who lack access to health care.

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