Change in kidney function over 3 months among salt workers in Thailand

Abstract

BACKGROUND AND AIM: Thailand is located in a hot and humid zone. Outdoor workers are vulnerable to high heat exposure, especially agricultural workers. Salt workers are considered manual labor with prolonged physical exertion, and the harvest season is in the hottest period of the year. The objective of the present study was to investigate the changes of kidney biomarkers over a harvest season. METHODS: Kidney biomarkers of 50 salt workers aged 18-60 were examined after work shift at the beginning of the harvest season and at the end of the harvest season (3 months later). The Wet Bulb Globe Temperature was used to measure heat exposure during workdays. Individual factors and work-related factors were assessed by questionnaires. RESULTS:The median of heat index was 29.82°C at the beginning of the harvest season and increased to 33.89°C at the end of the season. Salt workers worked on average 5 hours continuously. Above 50% of them took a rest less than 2 times on working days. Approximately 48% of participants had a heavy workload which over the standard of exposure to heat and hot environment of Thailand (not over 30°C). The median of serum creatinine (Scr) and blood urea nitrogen (BUN) increased over time. The estimated glomerular filter rate (eGFR) decreased by 15.2 ml/min/1.73 m2 over the harvest season. There were statistically significant changes over season in Scr (p-value =0.001), BUN (p-value=0.004) and eGFR (p-value 0.001). CONCLUSIONS:Kidney function of salt workers can substantially decrease in only 3 months during a harvest season. Recommendations and protections to salt workers have to be placed. KEYWORDS: Temperature, Heat exposure, Agricultural work