Short-term effects of subchronic low-level hydrogen sulfide exposure on oil field workers

Objectives

To investigate the short-term effects of low-level hydrogen sulfide (H₂S) exposure on oil field workers.

Materials and methods

Observational study included 34 patients who work at an oil field. All patients were males with age range of 22–60 years (mean 37 years). The data were collected by systematic questionnaire about symptoms. The inclusion criteria of patients were symptoms related to inhalation of H₂S gas in the oil field. The complaints should be frequent and relapsed after each gas exposure and disappeared when there was no gas exposure. Exclusion criteria were the symptoms which experienced with or without H₂S exposure. The presence of H₂S gas was confirmed by valid gas detector devices.

Results

The most frequent presenting symptom was nasal bleeding. It was revealed in 18 patients (52.9 %). This followed by pharyngeal bleeding, gum bleeding, and bloody saliva (mouth bleeding) which were encountered in five cases for each complaint (14.7 %). Other less frequent presenting symptoms were tongue bleeding, bloody sputum, headache, abdominal colic, pharyngeal soreness, fatigue, and sleepiness.

Conclusions

Nasal mucosa was the most vulnerable part to H₂S effect. Inhalation of H₂S produced upper respiratory tract epithelial damage that led to bleeding from nose, pharynx, gum, tongue, trachea, and bronchi. There were no complaints of asthmatic attack upon exposure to low level of H₂S. Sunlight had a significant role in reduction of ambient air H₂S level.