The risk of pterygium in salt workers

To find out if exposure to direct and reflected sunlight in brine pans (ground water rich in salt, kept in wide pans in open air for salt manufacturing), increases the risk of pterygium in exposed salt workers.

It was a cross sectional observational study, in which 865 salt workers were examined in the Free Occupational Health Check-up camps held near salt sites; 304 persons from the same area engaged in other work were examined as controls. The prevalence of pterygium in different age groups was compared between brine workers (who worked in the brine pans), dry salt workers, (who were engaged in the loading, weighing, milling, packing or transportation of the dry salt but never worked in brine pans) and non-salt-worker controls.

The prevalence of pterygium was significantly higher in brine workers (21.0%) as compared to dry salt workers (9.1%) (Yates corrected chi(2) = 23.45, p = 0.000001) and non-salt-worker controls (9.4%) (Yates corrected chi(2) = 15.69, p = 0.00007). It increased with age and duration of employment in the salt industry.

Brine workers have a higher risk of developing pterygium probably due to their exposure to sunlight reflected both from the surface of brine and from the surface of salt crystals.