Chronic ambient hydrogen sulfide exposure and cognitive function

摘要

Background: Exposures to hydrogen sulfide gas (H_2S) have been inconclusively linked to a variety of negative cognitive outcomes. We investigated possible effects on cognitive function in an urban population with chronic, low-level exposure to H_2S. Methods: Participants were 1637 adults, aged 18-65 years from Rotorua city, New Zealand, exposed to ambient H_2S from geothermal sources. Exposures at homes and workplaces were estimated from data collected by summer and winter H_2S monitoring networks across Rotorua in 2010/11. Metrics for H_2S exposure at the time of participation and for exposure over the last 30 years were calculated. H_2S exposure was modeled both as continuous variables and as quartiles of exposure covering the range of 0-64 ppb (0-88 ug/m3). Outcomes were neuropsychological tests measuring visual and verbal episodic memory, attention, fine motor skills, psychomotor speed and mood. Associations between cognition and measures of H_2S exposure were investigated with multiple regression, while covarying demographics and factors known to be associated with cognitive performance. Results: The consistent finding was of no association between H_2S exposure and cognition. Quartiles of H_2S exposure had a small association with simple reaction time: higher exposures were associated with faster response times. Similarly, for digit symbol, higher H_2S exposures tended to be marginally associated with better performance. Conclusion: The results provide evidence that chronic H_2S exposure, at the ambient levels found in and around Rotorua, is not associated with impairment of cognitive function.