Summary of Hydrogen Sulfide Toxicity (H2S)
During June people living in Venice, Louisiana near EPA’s air pollution test station (V06) breathed toxic hydrogen sulfide gas at concentrations up to 40 times in excess of minimum risk levels set by government health agencies.
During June people living in Venice, Louisiana near EPA’s air pollution test station (V06) breathed toxic hydrogen sulfide gas at concentrations up to 40 times in excess of minimum risk levels set by government health agencies.
In Venice, LA on June 20 a 1-hr reading of 0.8 ppm Hydrogen Sulfide is 11 times the Minimum Risk Level (MRL) for intermediate exposure (1-14 days)
Dangerous gases are entering the air directly from the million gallons of crude oil and tens of millions of cubic feet of natural gas blowing into the Gulf waters every day.
Recent EPA Readings of Hydrogen Sulfide gas in Venice, LA
Venice, Louisiana June 20 (EPA station VO6)
0.8 ppm 1-hr reading, June 20
0.7 ppm 1-hr reading, June 20
0.6 ppm 1-hr reading, June 20
0.5 ppm 1-hr reading, June 20
0.4 ppm = 24-hour average, June 20
0.10 ppm = daily average for month of June 2010
0.07 Minimum Risk Level for acute exposure (1-14 days)
0.02 Minimum Risk Level for intermediate exposure
Interpretation:
Average for June 20 is 5.7 times MRL-acute and 20 times MRL-intermediate.
Daily average for June is 1.4 times MRL-acute and 5 times MRL-intermediate.
Samples in Other Coast Locations:
0.5 ppm 1-hr reading, June 19 Alabama (EPA station 061910-6)
0.4 ppm 1-hr reading, June 19 Alabama (EPA station 061910-5)
0.3 ppm 1-hr reading, June 20 Alabama (EPA station 062110-3)
0.3 ppm 1-hr reading, June 23 Alabama (EPA station 062310-2)
ATSDR uses the no observed adverse effect level/uncertainty factor (NOAEL/UF) approach to derive MRLs for hazardous substances. They are set below levels that, based on current information, might cause adverse health effects in the people most sensitive to such substance induced effects. MRLs are derived for acute (1-14 days), intermediate (>14-364 days), and chronic (365 days and longer) exposure durations, and for the oral and inhalation routes of exposure.
MRLs are based on non cancer health effects only and are not based on a consideration of cancer effects.
Minimum Risk Level (MRL) set by Agency for Toxic Substances and Disease Registry (ATSDR) for acute exposure (1-14 days) to hydrogen sulfide (H2S gas is 0.07 ppm (parts per million).
MRL set by ATSDR for intermediate exposure (14-364 days) to hydrogen sulfide gas is 0.02 ppm.
Hydrogen sulfide is a flammable, colorless gas with a characteristic odor of rotten eggs. The sense of smell becomes rapidly fatigued & can NOT be relied upon to warn of the continuous presence of H2S. There is considerable individual variability in the odor threshold for hydrogen sulfide in humans; the thresholds can range from 0.0005 to 0.3
ppm. At high concentrations individuals may lose their ability to smell it. This can make hydrogen sulfide very dangerous.
If exposed to hydrogen sulfide, children are more vulnerable than adults. Target organs are eyes, respiratory system and central nervous system.
Symptoms of hydrogen sulfide exposure can be noticed in the eyes. Eyes may become irritated and painful. A person may experience a discharge of tears, abnormal visual intolerance to light and possible corneal blistering. The membrane lining the eyelids may become inflamed or infected. Vision may be blurred. Crusts may form on the eyelids overnight.
Breathing and nerve symptoms can be dizziness, headache, lassitude (weakness, exhaustion), irritability, insomnia and gastrointestinal disturbance. The gas can cause sore throat, cough and gasping for breath. Impaired lung function has been observed in asthmatics.
Exposure to high levels of hydrogen sulfide results in convulsions, coma and unconsciousness followed by apparent recovery, colloquially referred to as “knockdown”. Some individuals report permanent or persistent neurological effects after the apparent recovery.
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