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Sensory and cognitive effects of acute exposure to hydrogen sulfide.

Fiedler N, Kipen H, Ohman-Strickland P, Zhang J, Weisel C, Laumbach R, Kelly-McNeil K, Olejeme K, Lioy P - Environ. Health Perspect. (2008)

Bottom Line: Dose-response reduction in air quality and increases in ratings of odor intensity, irritation, and unpleasantness were observed.No dose-response effect was observed for sensory or cognitive measures.Increased anxiety was significantly related to ratings of irritation due to odor.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental and Occupational Medicine, UMDNJ-Robert Wood Johnson Medical School, 170 Frelinghuysen Rd., Rm. 210, Piscataway, NJ 08854 USA.. nfiedler@eohsi.rutgers.edu <nfiedler@eohsi.rutgers.edu>

ABSTRACT

Background: Some epidemiologic studies have reported compromised cognitive and sensory performance among individuals exposed to low concentrations of hydrogen sulfide (H2S).

Objectives: We hypothesized a dose-response increase in symptom severity and reduction in sensory and cognitive performance in response to controlled H2S exposures.

Methods: In separate exposure sessions administered in random order over three consecutive weeks, 74 healthy subjects [35 females, 39 males; mean age (+/- SD) = 24.7 +/- 4.2; mean years of education = 16.5 +/- 2.4], were exposed to 0.05, 0.5, and 5 ppm H2S. During each exposure session, subjects completed ratings and tests before H2S exposure (baseline) and during the final hour of the 2-hr exposure period.

Results: Dose-response reduction in air quality and increases in ratings of odor intensity, irritation, and unpleasantness were observed. Total symptom severity was not significantly elevated across any exposure condition, but anxiety symptoms were significantly greater in the 5-ppm than in the 0.05-ppm condition. No dose-response effect was observed for sensory or cognitive measures. Verbal learning was compromised during each exposure condition.

Conclusions: Although some symptoms increased with exposure, the magnitude of these changes was relatively minor. Increased anxiety was significantly related to ratings of irritation due to odor. Whether the effect on verbal learning represents a threshold effect of H2S or an effect due to fatigue across exposure requires further investigation. These acute effects in a healthy sample cannot be directly generalized to communities where individuals have other health conditions and concomitant exposures.

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Related in: MedlinePlus

Timeline of events during each exposure session. Abbreviations: CS, contrast sensitivity vision test; Guess, exposure guess questionnaire; NES, Continuous Performance, Simple Reaction Time, Finger Tapping, Symbol Digit Substitution; Sym, symptom.
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f2-ehp0116-000078: Timeline of events during each exposure session. Abbreviations: CS, contrast sensitivity vision test; Guess, exposure guess questionnaire; NES, Continuous Performance, Simple Reaction Time, Finger Tapping, Symbol Digit Substitution; Sym, symptom.

Mentions: Each experimental session was 3 hr in duration and occurred in the morning to control for the effects of circadian rhythms (Figure 2). On the day before each testing session and on the day of testing, subjects were asked not to use caffeine or alcohol. Subjects also could not have an active upper respiratory illness (either infection or allergy) nor use medication for allergies or other respiratory conditions for 1 week before the onset of the study or during the study. For subject safety, EKG electrodes monitored heart rate and variability during all exposure conditions. On the day of each experimental session, subjects reported to the Clinical Center at 0830, and a nurse performed a check-in to ascertain that the above conditions were met. Women were given a pregnancy test. Subjects completed the symptom questionnaire (clinic baseline) and then were escorted to the CEF where they were seated in a standard nonpadded office chair. Subjects rested quietly for 5 min, after which they completed the symptom questionnaire and odor and environmental ratings (10 min), and performed the sway test, contrast sensitivity test, and the cognitive tasks (baseline). (All times given are the approximate times after each task began.) Neither subjects nor the experimenters responsible for monitoring subjects and conducting each session were told the exposure conditions, and subjects were randomly assigned to one of six possible exposure orders (e.g., 5, 0.05, 0.5 ppm). However, the exposure technician was aware of the exposure condition in order to monitor exposure concentrations on each day. On completion of all tasks, the symptom questionnaire and odor and environmental ratings (70 min) were administered before exposure began. After the onset of exposure when exposure concentrations reached a steady state, the symptom questionnaire and odor and environmental ratings (80 min) were completed to obtain an immediate response to the odor of the exposure. During the next 10 min, subjects were asked to relax and read magazines provided and then to complete the odor ratings (90 min). During the next 5-min period, subjects completed the CPT task. The symptom questionnaire and odor and environmental ratings (100 min) were then completed and subjects were allowed to read for 10 min. After completion of the odor and environmental ratings (110 min), the subject read for 10 min and then completed odor and environmental ratings and symptom questionnaire (120 min). After 45 minutes of exposure, the sway test, contrast sensitivity, and cognitive tests required approximately 60 min to complete while exposure was ongoing. Subjects also completed another symptom questionnaire (165 min). Finally, subjects completed the symptom questionnaire and odor and environmental ratings (180 min) and were asked to guess the exposure condition. Immediately on termination of the protocol (~ 3 hr), subjects returned to the Clinical Center, removed the electrodes for heart monitoring, and completed the symptom questionnaire (clinic recovery). Subjects were allowed to leave the Clinical Center if their symptoms returned to the same level as recorded at baseline before exposure.


Sensory and cognitive effects of acute exposure to hydrogen sulfide.

Fiedler N, Kipen H, Ohman-Strickland P, Zhang J, Weisel C, Laumbach R, Kelly-McNeil K, Olejeme K, Lioy P - Environ. Health Perspect. (2008)

Timeline of events during each exposure session. Abbreviations: CS, contrast sensitivity vision test; Guess, exposure guess questionnaire; NES, Continuous Performance, Simple Reaction Time, Finger Tapping, Symbol Digit Substitution; Sym, symptom.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2199294&req=5

f2-ehp0116-000078: Timeline of events during each exposure session. Abbreviations: CS, contrast sensitivity vision test; Guess, exposure guess questionnaire; NES, Continuous Performance, Simple Reaction Time, Finger Tapping, Symbol Digit Substitution; Sym, symptom.
Mentions: Each experimental session was 3 hr in duration and occurred in the morning to control for the effects of circadian rhythms (Figure 2). On the day before each testing session and on the day of testing, subjects were asked not to use caffeine or alcohol. Subjects also could not have an active upper respiratory illness (either infection or allergy) nor use medication for allergies or other respiratory conditions for 1 week before the onset of the study or during the study. For subject safety, EKG electrodes monitored heart rate and variability during all exposure conditions. On the day of each experimental session, subjects reported to the Clinical Center at 0830, and a nurse performed a check-in to ascertain that the above conditions were met. Women were given a pregnancy test. Subjects completed the symptom questionnaire (clinic baseline) and then were escorted to the CEF where they were seated in a standard nonpadded office chair. Subjects rested quietly for 5 min, after which they completed the symptom questionnaire and odor and environmental ratings (10 min), and performed the sway test, contrast sensitivity test, and the cognitive tasks (baseline). (All times given are the approximate times after each task began.) Neither subjects nor the experimenters responsible for monitoring subjects and conducting each session were told the exposure conditions, and subjects were randomly assigned to one of six possible exposure orders (e.g., 5, 0.05, 0.5 ppm). However, the exposure technician was aware of the exposure condition in order to monitor exposure concentrations on each day. On completion of all tasks, the symptom questionnaire and odor and environmental ratings (70 min) were administered before exposure began. After the onset of exposure when exposure concentrations reached a steady state, the symptom questionnaire and odor and environmental ratings (80 min) were completed to obtain an immediate response to the odor of the exposure. During the next 10 min, subjects were asked to relax and read magazines provided and then to complete the odor ratings (90 min). During the next 5-min period, subjects completed the CPT task. The symptom questionnaire and odor and environmental ratings (100 min) were then completed and subjects were allowed to read for 10 min. After completion of the odor and environmental ratings (110 min), the subject read for 10 min and then completed odor and environmental ratings and symptom questionnaire (120 min). After 45 minutes of exposure, the sway test, contrast sensitivity, and cognitive tests required approximately 60 min to complete while exposure was ongoing. Subjects also completed another symptom questionnaire (165 min). Finally, subjects completed the symptom questionnaire and odor and environmental ratings (180 min) and were asked to guess the exposure condition. Immediately on termination of the protocol (~ 3 hr), subjects returned to the Clinical Center, removed the electrodes for heart monitoring, and completed the symptom questionnaire (clinic recovery). Subjects were allowed to leave the Clinical Center if their symptoms returned to the same level as recorded at baseline before exposure.

Bottom Line: Dose-response reduction in air quality and increases in ratings of odor intensity, irritation, and unpleasantness were observed.No dose-response effect was observed for sensory or cognitive measures.Increased anxiety was significantly related to ratings of irritation due to odor.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental and Occupational Medicine, UMDNJ-Robert Wood Johnson Medical School, 170 Frelinghuysen Rd., Rm. 210, Piscataway, NJ 08854 USA.. nfiedler@eohsi.rutgers.edu <nfiedler@eohsi.rutgers.edu>

ABSTRACT

Background: Some epidemiologic studies have reported compromised cognitive and sensory performance among individuals exposed to low concentrations of hydrogen sulfide (H2S).

Objectives: We hypothesized a dose-response increase in symptom severity and reduction in sensory and cognitive performance in response to controlled H2S exposures.

Methods: In separate exposure sessions administered in random order over three consecutive weeks, 74 healthy subjects [35 females, 39 males; mean age (+/- SD) = 24.7 +/- 4.2; mean years of education = 16.5 +/- 2.4], were exposed to 0.05, 0.5, and 5 ppm H2S. During each exposure session, subjects completed ratings and tests before H2S exposure (baseline) and during the final hour of the 2-hr exposure period.

Results: Dose-response reduction in air quality and increases in ratings of odor intensity, irritation, and unpleasantness were observed. Total symptom severity was not significantly elevated across any exposure condition, but anxiety symptoms were significantly greater in the 5-ppm than in the 0.05-ppm condition. No dose-response effect was observed for sensory or cognitive measures. Verbal learning was compromised during each exposure condition.

Conclusions: Although some symptoms increased with exposure, the magnitude of these changes was relatively minor. Increased anxiety was significantly related to ratings of irritation due to odor. Whether the effect on verbal learning represents a threshold effect of H2S or an effect due to fatigue across exposure requires further investigation. These acute effects in a healthy sample cannot be directly generalized to communities where individuals have other health conditions and concomitant exposures.

Show MeSH
Related in: MedlinePlus