# Electrolyte Imbalance and Indirect Indicators of Dehydration in Temporary Agricultural Workers Exposed to Extreme Heat in the Mediterranean: An Observational Study on Environmental Health Risks

## TL;DR

This study shows that Mediterranean agricultural workers exposed to extreme heat experience significant dehydration and electrolyte loss, with sweat being a key indicator of health risks.

## Contribution

The study provides new empirical data on electrolyte imbalance and dehydration in Mediterranean agricultural workers due to extreme heat.

## Key findings

- Participants lost an average of 0.8 kg and produced 3.91 L of sweat over nine days.
- Sweat loss strongly correlated with sodium and potassium depletion.
- Diastolic blood pressure was moderately linked to weight loss, indicating dehydration risk.

## Abstract

What are the main findings?
Agricultural workers in the Mediterranean are highly exposed to heat-related health risks.Heat exposure impacts cardiovascular and thermoregulatory functions.

Agricultural workers in the Mediterranean are highly exposed to heat-related health risks.

Heat exposure impacts cardiovascular and thermoregulatory functions.

What are the implications of the main findings?
Continuous monitoring of physiological signs can help prevent heat-related disorders.Adaptive and preventive strategies are essential to protect vulnerable outdoor laborers.

Continuous monitoring of physiological signs can help prevent heat-related disorders.

Adaptive and preventive strategies are essential to protect vulnerable outdoor laborers.

Background: Climate change is intensifying extreme heat exposure in Mediterranean agricultural systems. Migrant workers engaged in outdoor fieldwork are a highly vulnerable population with limited access to resources. Crucially, there is a notable lack of data on how heat affects these workers in this specific region. Objective: This study aimed to analyze the physiological effects of high-temperature exposure by quantifying and correlating indirect indicators of dehydration and electrolyte imbalance (sodium and potassium losses, sweat, body weight, and blood pressure). Methods: An observational study was conducted over nine consecutive days involving ten agricultural participants, yielding 90 observations. Measurements of body weight, heart rate, blood pressure, skin temperature, sweat loss, and sodium and potassium concentrations were taken before, during, and after daily field activity. Results: Results showed considerable interindividual variability in thermophysiological responses. Participants lost an average of 0.8 kg (range –9.1 to +3.6 kg) and produced 3.91 L of sweat (range 1.9–6.4 L), with sodium and potassium losses of 4932 mg and 646 mg, respectively. Sweat loss correlated with sodium (r = 0.414, p = 0.001) and potassium (r = 0.791, p < 0.001), and diastolic blood pressure was moderately associated with weight loss (r = 0.576, p = 0.016). Conclusions: Sweat loss was the main driver of electrolyte depletion, with marked interindividual variability. Monitoring sweat-related indicators and diastolic blood pressure could help detect dehydration risk in agricultural workers exposed to extreme heat. Targeted hydration strategies and occupational health education are essential to mitigate these risks.