Cognitive Functions Changes Among Egyptian Sewage Network Workers

Abstract

Abstract:Objectives: The current work aimed at investigating the cognitive functions impairment among workers of sewer networks due to exposure to H2S and the relation of this impairment ,if any, to the level of H2S exposure biomarker "urinary thiosulfate". Besides, the validity of using Mini Mental State Examination (MMSE) as screening test for cognitive impairment among the exposed workers was tested. Subjects:The work was conducted among 33 sewage network maintenance male workers and a matched unexposed control group (n= 30). Methods:The participants were subjected to clinical neurological history, estimation of urinary thiosulfate, and assessment of cognitive dysfunction by using neurophysiological (simple reaction time, P300 test) and neuropsychological tests (Wechsler Memory Scale) and frontal executive functions tests.Results: Clinical neurological history revealed significantly higher neurological symptoms (headache, memory defects, lack of concentration) among exposed workers compared to their controls (P< 0.05). Exposed workers had significantly prolonged simple reaction time and delayed P300 latency and showed poor performance of most of neuropsychological tests. Marked elevation of urinary thiosulfate was observed among the exposed workers (P< 0.001) but this elevation was not correlated with the duration of exposure or any of the other measured parameters. Exposed workers had significantly lower mean value of MMSE scoring than that of the controls (P<0.001). Conclusion:Exposure to H2S among sewer network workers is associated with cognitive impairment which can be screened by applying MMSE as a simple rapid test for hydrogen sulfide occupationally exposed workers.

Systematic Review of Potential Occupational Respiratory Hazards Exposure Among Sewage Workers

“…Usually, sewage workers were more exposed to the incidental H 2 S peak type of exposure than constant exposure. H 2 S was also found to cause negative respiratory effects and cause central nervous systemrelated symptoms, such as tiredness and concentration difficulties among the sewage workers (47).…”

Hydrogen sulphide

“…In waste water and sewerage treatment plants, biogas plants, industrial and manufacturing processes, chemical, petrochemical and oil refining processes, during production, storage and transportation, H₂S is known to be highly toxic even at low concentrations. It has been proven to cause cognitive impairment [58] and has also been linked to neurological symptoms and health effects on the central nervous system and respiratory functions [59]. In a study of nearly 150 wastewater workers, for whom H₂S is frequently an occupational health and safety hazard, an inflammation was found, albeit low but pervasive, symptomatic of the effect on lung capacity through exposure to workaday strength H₂S [60].…”