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HEALTH CONSULTATION

MOUNTAIN VIEW SEWER GAS INVESTIGATION
SCOTTSDALE, MARICOPA COUNTY, ARIZONA


OBJECTIVE

The Arizona Department of Health Services (ADHS) is a cooperative agreement partner of the Agency for Toxic Substances and Disease Registry (ATSDR) headquartered in Atlanta, Georgia. The Agency for Toxic Substances and Disease Registry is an agency within the U.S. Department of Health and Human Services. The mission of the Agency for Toxic Substances and Disease Registry is to take responsive public health actions and to provide information to prevent harmful exposures and disease related to toxic substances.

In May 2003, a Scottsdale, Arizona, resident asked the Agency for Toxic Substances and Disease Registry in Atlanta to investigate possible sewer gas exposures in a Scottsdale residential neighborhood. In June 2003, the Agency for Toxic Substances and Disease Registry asked the Arizona Department of Health Services to conduct an investigation to determine if sewer gas exposures were occurring. Because ambient 1 and indoor air hydrogen sulfide data for the neighborhood were not available, the Arizona Department of Health Services and the resident collaborated in conducting an air monitoring investigation in the neighborhood from June 26, 2003, through July 15, 2003. The findings of the investigation were evaluated by the Office of Environmental Health within the Arizona Department of Health Services, and the results of the evaluation are presented in this health consultation.


BACKGROUND

In a May 20, 2003, letter to the Agency for Toxic Substances and Disease Registry and the Arizona Department of Health Services, the Scottsdale resident described discharges of sewer gas from manholes and a residential rooftop vent stack in the neighborhood. The resident stated in the letter that physical illnesses in some neighborhood residents, as well as symptoms the resident experienced while observing the sewer gas discharges, were similar to symptoms caused by exposure to hydrogen sulfide gas.

The resident's letter indicated there were occasional but significant discharges of sewer gas from manholes west of N. 64th Street in Scottsdale on E. Mountain View Road (see Appendix A for a map of the neighborhood). During these discharges, it was possible to detect sewer gas odor more than 50 feet from some manholes. Furthermore, on one occasion, while the manholes were discharging sewer gas, the main 4-inch vent stack on the roof of a nearby residence was also emitting a strong, continuous discharge of sewer gas. The resident pointed out that hydrogen sulfide, the main constituent of sewer gas, is slightly heavier than air and, therefore, the discharge could be settling to ground level in the neighborhood.

From sewer system engineering drawings obtained from the City of Phoenix, the resident concluded that the out-gassing was probably caused by a bottleneck at the intersection of E. Mountain View Road and N. 64th Street. At this intersection, the 33-inch diameter sewer main running east under E. Mountain View Road makes a 90-degree bend and empties into a smaller 27-inch diameter sewer main running south under N. 64th Street. The resident also suggested that an additional source of gas generation may be turbulence caused by two 8-inch feeder lines emptying into the 33-inch diameter sewer from opposite directions on E. Mountain View Road.


COMMUNITY HEALTH EFFECTS

In preparing to conduct the investigation, the Arizona Department of Health Services learned that another homeowner in the Scottsdale neighborhood had contacted the city of Phoenix on a number of occasions in previous years regarding sewer gas odors. City of Phoenix examinations of the sewer system indicated nothing wrong with the city sewer system. In an interview with Arizona Department of Health Services staff, the homeowner stated there had been a sewer gas problem in the neighborhood for years and that the homeowner had suffered many symptoms and illnesses as a result of repeated exposures to the gas.

No neighborhood residents lodged formal complaints with the Arizona Department of Health Services during or after the investigation. However, two residents during one monitoring event and one resident during another monitoring event approached department staff and said there had been a pervasive sewer gas odor in the neighborhood. The residents did not specify how long the sewer gas odor had been present in the neighborhood.


HEALTH EFFECTS OF SEWER GAS

Sewer Gas

Sewer gas is a generic name for a complex mixture of gases and airborne agents that result from the natural process of the decomposition of organic materials in sewage. Gases produced by domestic wastewater decomposition commonly include hydrogen sulfide (H2S), ammonia (NH3), methane (CH4), and carbon dioxide (CO2). Of these gases, only hydrogen sulfide and ammonia are malodorous. Sewer gas also contains sulfur dioxide (SO2), nitrous oxides (NOx), biological organisms, water vapor, and chemicals introduced into wastewater such as chlorine bleaches, industrial solvents, and gasoline. The presence and concentration of these components can vary with time, composition of the sewage, temperature, and pH (Hutter 1993; WDHFS 2003).

In urban residential neighborhoods, sewer gas can enter ambient air through manholes, pumping stations, rooftop vent stacks, and other routes. Sewer gas can enter indoor air in homes through floor drains, dried-out sewer traps, or cracks in the foundation (if the gases are in soil adjacent to the house), or from leaking or blocked roof vents.

The major adverse health effects and hazards from exposure to sewer gas include the following:

  1. Poisoning from hydrogen sulfide gas;
  2. Decreased vigilance or fatigue due to reduced oxygen levels (from CO2 and CH4);
  3. Diseases from airborne sewage pathogens, i.e., bacteria, viruses, parasites (however, these microbes are short-lived when suspended in air);
  4. Fires and explosions from methane gas, hydrogen sulfide, or other flammable gases accumulating in an enclosed space (Hutter 1993).

Hydrogen Sulfide (H2S)

Hydrogen sulfide is the most commonly known and prevalent odorous gas associated with domestic wastewater. It is also the sewer gas component of greatest health concern (Dr. Selene Chou, ATSDR, personal communication, 2003). The conditions leading to hydrogen sulfide formation generally favor production of other malodorous organic gases. Many of those are also sulfur-bearing compounds, such as mercaptans and dimethyl disulfide. Because of this association, solving for hydrogen sulfide odor problems can often resolve other odor problems (Alken-Murray 2003).

Hydrogen sulfide is a colorless, flammable, highly toxic gas with a characteristic rotten egg odor. The reported odor threshold for hydrogen sulfide gas varies greatly, but it is generally less than 0.01 parts per million (ppm) (McGavran 2001). Some people may be able to detect the odor of hydrogen sulfide in air at concentrations as low as 0.0005 ppm (ATSDR 1999). Hydrogen sulfide can be especially dangerous because at concentrations over 100 ppm or at continuous low exposure concentrations most people can no longer smell hydrogen sulfide, making them unaware that they continue to be exposed to the gas (ATSDR 1999). Hydrogen sulfide is likely to remain in ambient air for less than one day, but it may persist for as long as 42 days (WHO 2003). The average hydrogen sulfide background concentration in the air in the United States is estimated to be between 0.0001 and 0.0003 ppm. The concentration of hydrogen sulfide in air in undeveloped areas of the United States is very low, between 0.00002 and 0.00007 ppm (ATSDR 1999).

Because hydrogen sulfide is a gas, inhalation is the major route of exposure, and the gas is rapidly absorbed through the lungs (WHO 2003). Hydrogen sulfide is a "broad spectrum" poison, meaning it can poison several different systems of the body (ATSDR 1999). Exposure to high concentrations of hydrogen sulfide is reported to be the most common cause of sudden death in the workplace (Collins 2000). At high concentrations, such as may occur in a confined workspace, hydrogen sulfide can cause severe lung inflammation, loss of consciousness, convulsions, respiratory arrest, heart failure, and death.

At low exposure levels, as are likely to occur in a residential area such as the Mountain View neighborhood, hydrogen sulfide will primarily cause eye and respiratory tract irritation (McGavran 2001). Prolonged exposure to low concentrations has not been well studied. However, low concentrations have been associated with neurological symptoms, including fatigue, headache, nausea, dizziness, loss of appetite, irritability, impaired memory, and altered mood states (McGavran 2001). Absent any physical effects, the odor of hydrogen sulfide alone can be annoying and affect well being. None of the available studies demonstrate that hydrogen sulfide causes cancer. Table 1, taken from a report by the World Health Organization, shows health effects of various hydrogen sulfide concentrations in air (WHO 2003).

Table 1.

Human Health Effects at Various Hydrogen Sulfide Concentrations in Air
Exposure (ppm) Effect/Observation Reference
0.0005-0.01 Odor threshold ATSDR 1999; McGavran 2001
0.01-0.6 Increased eye symptoms
Increases in nausea
Increased headache, mental symptoms, diseases of nervous system and sense organs
ATSDR 1999 (see Appendix B)
2.0 Bronchial constriction in asthmatic individuals WHO 2003; ATSDR 1999
5.0 Increased eye complaints
Mild respiratory, cardiovascular, musculoskeletal, and metabolic changes
WHO 2003
ATSDR 1999 (see Appendix B)
3.6-21 Eye irritation WHO 2003
20 Fatigue, loss of appetite, headache, irritability, poor memory, dizziness
Irritation of mucous membranes
WHO 2003
ATSDR 1999
100 Olfactory paralysis ATSDR 1999
>560 Respiratory distress WHO 2003
700 Death WHO 2003

Enforceable Hydrogen Sulfide (H2S) Standards

Table 2 shows government standards and guidelines applicable to hydrogen sulfide levels in air. Regulatory standards are enforceable under the law, but guidelines are nonbinding and not enforceable. Hydrogen sulfide in ambient air is not classified as a criteria air pollutant or a hazardous air pollutant under the federal Clean Air Act and, consequently, is not regulated by either the U.S. Environmental Protection Agency or the Arizona Department of Environmental Quality. The only enforceable hydrogen sulfide air quality standards in effect at this time are the Occupational Safety and Health Administration occupational regulations shown at the top of Table 2. The Occupational Safety and Health Administration set an 8-hour permissible exposure limit (PEL) of 10 ppm for hydrogen sulfide in the workplace and an acceptable ceiling concentration of 20 ppm, with a maximum level of 50 ppm allowed for 10 minutes if no other measurable exposure occurs. The Occupational Safety and Health standards are applicable to the workplace only.

Table 2.

Standards and Guidelines Applicable to Hydrogen Sulfide in Air
Federal Regulations
Occupational Safety and Health (OSHA) Permissible exposure limit (PEL)–8-hour
Short-term exposure limit (STEL)–15 minutes
Acceptable ceiling concentration
Peak–one-time 10-minute maximum exposure
10 ppm
15 ppm
20 ppm
50 ppm
Federal Guidelines
Agency for Toxic Substances and Disease Registry (ATSDR) Comparison value (CV)
   Acute
   Intermediate
Minimal risk levels (MRLs)
   Acute (1–14 days)
   Intermediate (14–364 days)


0.07 ppm
0.03 ppm

0.07 ppm
0.03 ppm

National Institute for Occupational Safety and Health (NIOSH) Recommended exposure limit (REL)–10 minute exposure ceiling 10 ppm
American Conference of Governmental Industrial Hygienists (ACGIH) Threshold limit value/time-weighted average (TLV/TWA)
Threshold limit value/short-term exposure limit (TLV/STEL)
10 ppm
15 ppm
World Health Organization (WHO) 24-hour average
30-minute odor annoyance guideline
0.11 ppm
0.005 ppm
U.S. Environmental Protection Agency (EPA) Reference concentration (RfC)–noncancer
No-observed-adverse-effect-level (NOAEL)
0.001 ppm
10 ppm
Arizona (Draft) Guidelines
Arizona Department of Environmental Quality (ADEQ) Arizona ambient air quality guidelines (AAAQGs)
   1-hour AAAQG
   24-hour AAAQG
 
0.13 ppm
0.08 ppm

Hydrogen Sulfide Guidelines (ATSDR and EPA)

The (nonenforceable) guidelines for hydrogen sulfide in air that are of greatest interest to health assessors are the the Agency for Toxic Substances and Disease Registry comparison values (CVs) and minimal risk levels (MRLs), and the U.S. Environmental Protection Agency reference concentrations (RfCs) (see Table 2). The Agency for Toxic Substances and Disease Registry comparison values are screening values conservatively developed based on the most sensitive receptors. A contaminant level that exceeds a comparison value does not necessarily indicate a health risk but rather that the contaminant is present in the environment at levels that warrant further evaluation. The Agency for Toxic Substances and Disease Registry minimal risk levels are estimates of daily human exposure to a hazardous substance likely to be without appreciable risk of adverse, noncancer health effects. The comparison values/minimal risk levels for hydrogen sulfide are 0.07 ppm for acute (1-14 day exposure) and 0.03 ppm for intermediate (14-364 day exposure). Although a chronic (>364 day exposure) comparison value/minimal risk level would be most applicable to long-term ambient air exposures to hydrogen sulfide gas, chronic values have not been developed for hydrogen sulfide gas due to insufficient data. The Agency for Toxic Substances and Disease Registry minimal risk levels for hazardous substances can be found at URL: http://www.atsdr.cdc.gov (ATSDR 2003).

The U.S. Environmental Protection Agency developed an inhalation reference concentration for hydrogen sulfide that is used to assess human health risks. The reference concentration is an estimate of a daily inhalation exposure concentration that is likely to be without an appreciable risk of adverse, noncancer effects during a lifetime. The inhalation reference concentration for hydrogen sulfide was developed from a no-observed-adverse-affect-level (NOAEL) of 10 ppm derived from a study of nasal inflammation in rats caused by exposure to hydrogen sulfide.

To obtain the reference concentration, the no-observed-adverse-affect-level (NOAEL) of 10 ppm was divided by an uncertainty factor (UF) of 300 obtained by multiplying a factor of 3 for extrapolating from animals to humans; a factor of 10 to protect sensitive individuals; and a factor of 10 to adjust from subchronic to chronic exposure. The resulting reference concentration is 0.001 ppm (0.002 mg/m3) (EPA 2003). The U.S. Environmental Protection Agency also developed a lowest-observed-adverse-affect-level (LOAEL) for hydrogen sulfide of 30 ppm. The lowest-observed-effect-level (LOAEL) is the lowest dose of chemical that produces adverse effects. Further information on the reference concentration, the no-observed-adverse-affect-level (NOAEL), and the lowest-observed-adverse-affect-level (LOAEL) for hydrogen sulfide can be found online in the U.S. Environmental Protection Agency's Integrated Risk Information System (IRIS) at URL: http://www.epa.gov/iris (EPA 2003).

Low Dose Studies

Appendix B contains a table summarizing the results of studies conducted on the health effects of low dose exposure (<10 ppm) to hydrogen sulfide and total reduced sulfur (TRS). The table was compiled from the Agency for Toxic Substances and Disease Registry's Toxicological Profile for Hydrogen Sulfide (ATSDR 1999). These studies suggest that exposure to hydrogen sulfide from 5 to 16 ppm may cause respiratory, cardiovascular, musculoskeletal, dermal, and metabolic health effects, while ocular, gastrointestinal, and neurological effects may occur below 1 ppm.

Appendix B also shows the results of low dose exposure to total reduced sulfur. Total reduced sulfur is a complex mixture of hydrogen sulfide, methyl mercaptan, and methyl sulfides from pulp mills. Because the observed health effects were caused by exposure to a mixture (although the authors indicate that hydrogen sulfide comprised the dominant sulfur compound of the mixture at about two thirds), caution must be used in drawing conclusions from these studies. The Toxicological Profile for Hydrogen Sulfide containing the studies referenced in Appendix B is available at URL: http://www.atsdr.cdc.gov/toxprofiles/tp114.html.


METHODS AND RESULTS

Target Population

Homes within the area where off-gassing and sewer gas odor had been detected by the resident were the primary focus of the investigation. This area, shown in Appendix A, is bounded by E. Mountain View Road on the south, E. Turquoise Avenue on the north, N. 64th Street on the east, and N. 61st Place on the west. There are 21 residences within this neighborhood with a maximum estimated potentially affected population of 80 residents. The Arizona Department of Health Services received approval from two residents, one of which was the resident who requested the investigation, to collect data inside their homes. If appreciable levels of sewer gas were detected in the Mountain View neighborhood, the study would have been expanded to surrounding neighborhoods.

Methods

The Arizona Department of Health Services and the resident collected ambient air hydrogen sulfide data in the neighborhood from June 26, 2003, through July 15, 2003. Data were collected with a hand-held BW Defender Multi-Gas Detector®, manufactured by BW Technologies Ltd. The multi-gas detector monitors four gases simultaneously and continuously: combustibles (methane), oxygen (deficiency/enrichment), carbon monoxide, and hydrogen sulfide. The multi-gas detector was capable of detecting the four gases to minimum detection (sensitivity) levels, but not below. The minimum detection levels for the meter were hydrogen sulfide–1 ppm, methane–1% lower explosive limit (LEL), carbon monoxide–1 ppm, and oxygen–0.1%.

Appendix C shows the dates and times data were collected and whether the data were collected by the resident or the Arizona Department of Health Services. Arizona Department of Health Services staff collected data in front of each residence in the neighborhood. Department sampling was usually from 10:00-11:00 AM because flow data from a wastewater metering station on E. Mountain View Road indicated that peak flows occurred in the neighborhood during this time. The resident, on the other hand, primarily collected data on a "spot-check" basis. The dates and times of resident sampling presented in Appendix C are from the McSweeney report (2003).

Results

The BW Defender Multi-Gas Detector® registered no detection of hydrogen sulfide in ambient or indoor air during the study, suggesting that hydrogen sulfide was not present in the neighborhood from June 26, 2003, through July 15, 2003, at levels equal to or greater than 1 ppm (the meter's lowest detection level for hydrogen sulfide). Nor did the meter detect carbon monoxide or methane in ambient or indoor air, suggesting that these compounds were also not present in the neighborhood at levels above the meter's lowest detection capability. No decreases in ambient or indoor oxygen were detected.

On several sampling occasions, Arizona Department of Health Services staff and the resident noted a mild sewer gas odor in ambient air downwind of manholes on E. Mountain View Road, suggesting that hydrogen sulfide may have been present at levels over the reported odor threshold of 0.0005-0.01 ppm (see Table 1). Over the weekend of June 26, 2003, just before the beginning of the study, the City of Phoenix sealed a manhole located at the intersection of E. Mountain View Road and N. 64th Street. According to the resident, the sewer gas odor was much stronger and widespread in the neighborhood before the manhole was sealed. An Arizona Department of Health Services employee visiting the neighborhood on June 17, 2003, before the manhole was sealed, noted strong sewer gas odors on E. Mountain View Road and in the area of the intersection of N. 62nd Place and E. Turquoise Avenue. After the manhole was sealed, the same Arizona Department of Health Services employee detected mild intermittent sewer gas odors on E. Mountain View Road only.


LIMITATIONS

The BW Defender Multi-Gas Detector® has the advantage of measuring combustibles, which could result in an explosion if accumulated in basements or other indoor space, and lowered oxygen associated with hydrogen sulfide in sewer gas; however, it has the disadvantage of having a minimum detection level (sensitivity) to hydrogen sulfide of only 1 ppm. This means that if hydrogen sulfide gas were present in the neighborhood at levels below 1 ppm, the meter would have been unable to detect these concentrations. The instrument, however, provided a screening tool to determine if immediate action was needed to prevent serious effects, such as bronchial restriction in asthmatic individuals or a physical hazard, such as the build-up of methane in a home.


DISCUSSION

Studies suggest that, in general, sewer gas production is greatest during the summer months, which should have maximized detection of hydrogen sulfide in the present investigation. Steven Davidson, a consulting engineer with extensive experience with wastewater collection systems in the Phoenix area, states in reference to the Phoenix metropolitan area, "Sulfide production is highly sensitive to wastewater temperature, and therefore, large seasonal variations in odor are typical in this area. Sulfide and hydrogen sulfide production are typically at least four times higher in the summer than in the winter. Thus, the time of greatest odor impact is most often in the summer, even though wastewater flow is significantly higher in the winter" (S. Davidson, Brown and Caldwell, letter to resident, July 23, 2003).

Hydrogen sulfide was not detected by the multi-gas detector, suggesting that hydrogen sulfide gas was not present in the neighborhood at 1 ppm or higher. Therefore, the health effects listed in Appendix B for exposures greater than 1 ppm would not be expected to occur in the neighborhood and are primarily presented for informational purposes.

However, hydrogen sulfide gas may have been present at times along E. Mountain View Road below the 1 ppm detection level of the meter. The studies in Appendix B suggest that concentrations of hydrogen sulfide in air below 1 ppm may cause olfactory, gastrointestinal, and neurological effects. The Agency for Toxic Substances and Disease Registry's comparison values for hydrogen sulfide in air–0.07 ppm (acute) and 0.03 ppm (intermediate)–and the U.S. Environmental Protection Agency's inhalation reference concentration of 0.001 ppm are below 1 ppm. Residents reported similar health effects described with exposure to lower levels of hydrogen sulfide prior to the city's action to seal one of the manholes. If residents report the odors or health effects again, specific exposures would need further evaluation with a more sensitive instrument.

The Agency for Toxic Substances and Disease Registry's comparison values are far below the Occupational Safety and Health Administration 8-hour standard for hydrogen sulfide in air of 10 ppm. The Occupational Safety and Health Administration believes that the safe limits of exposure of healthy workers to hydrogen sulfide gas are much greater than the odor detection level of the gas. Hydrogen sulfide levels that might be encountered in the Mountain View neighborhood are well within the Occupational Safety and Health Administration safe limits. However, the Occupational Safety and Health Administration standards were not established to be protective of people with respiratory problems or other sensitive populations.

Significant air pollution in the Phoenix metropolitan area further hampers efforts to identify the possible effects of low levels of hydrogen sulfide in the Mountain View neighborhood. Ozone, in particular, can affect the well being of sensitive individuals. Consequently, it can be difficult to separate health affects from hydrogen sulfide and other air pollutants.


CHILD HEALTH CONSIDERATIONS

The Agency for Toxic Substances and Disease Registry and the Arizona Department of Environmental Health recognize that the unique vulnerabilities of infants and children demand special emphasis in communities faced with contaminants in the air. There is little information in the literature to judge the effects of exposure to hydrogen sulfide on infants and children; however, it is likely that the same toxicity seen in adults will be seen in children.

It is generally thought that children are at greater risk than adults from exposure to ambient air pollutants. Children play outdoors more than adults. Children breathe a greater volume of air relative to body weight, resulting in a higher body burden of pollutants. Because hydrogen sulfide is slightly heavier than air and tends to sink, and because children are shorter than adults, children might be exposed to larger amounts of hydrogen sulfide than adults in the same situations. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages.


CONCLUSIONS

  • Levels of explosive gases and of hydrogen sulfide present at the time the Mountain View sewer gas investigation was conducted were below levels associated with physical hazards and serious health effects, such as bronchial restriction in asthmatic individuals. Therefore, at the time of the investigation, no apparent public health hazard was found. However, the instrument could not detect hydrogen sulfide at levels associated with less serious health effects.

  • Prior to the city's sealing of one manhole in the neighborhood, residents reported odors and short-term, less serious health effects, such as headaches, that are consistent with exposure to low levels of sewer gas.

RECOMMENDATIONS

  • If offensive sewer gas odors are noted in the future or residents report health effects associated with possible sewer gas exposure, neighborhood residents should notify the city of Phoenix and the Arizona Department of Health Services, Office of Environmental Health, and an investigation should be conducted using an instrument that can detect low levels of hydrogen sulfide. Screening for explosive levels of methane should also be conducted at that time.

PUBLIC HEALTH ACTION PLAN

The public health action plan for the Mountain View neighborhood describes actions taken and those to be taken at and near the site by the Agency for Toxic Substances and Disease Registry and the Arizona Department of Health Services. The purpose of the public health action plan is to identify potential and ongoing public health hazards and to provide a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment.

Completed, Ongoing, or Future Actions

  • The Arizona Department of Health Services measured levels of hydrogen sulfide, carbon monoxide, methane, and oxygen in ambient and indoor air in the Mountain View neighborhood from June 26, 2003, through July 15, 2003. At that time, no levels associated with physical hazards or serious health effects were found.

  • The Arizona Department of Health Services will consider reopening the investigation if residents report sewer gas odors and health effects in the neighborhood in the future.

REFERENCES

Alken-Murray Corporation. 2003. Sulfur compounds causing odor and corrosion. New Hyde Park, New York: Alken-Murray Corporation. Available from URL: http://www.alken-murray.com/H2SREM3.HTM. Last accessed September 10, 2003.

[ATSDR 1999] Agency for Toxic Substances and Disease Registry. 1999. Toxicological profile for hydrogen sulfide. Atlanta: US Department of Health and Human Services. Available from URL: http://www.atsdr.cdc.gov. Last accessed August 26, 2003.

[ATSDR 2003] Agency for Toxic Substances and Disease Registry. 2003. Minimal risk levels (MRLs) for hazardous substances. Atlanta: US Department of Health and Human Services. Available from URL: http://www.atsdr.cdc.gov/mrls.html. Last accessed August 26, 2003.

Collins J, Lewis D. 2000. Hydrogen sulfide: evaluation of current California air quality standards with respect to protection of children. Prepared for the California Air Resources Board. Sacramento: California Office of Environmental Health Hazard Assessment. Available from URL: http://www.oehha.org/air/pdf/oehhah2s.pdf. Last accessed August 26, 2003.

[EPA] US Environmental Protection Agency. 2003. Integrated risk information system (IRIS). Duluth, Minnesota: US Environmental Protection Agency. Available from URL: http://www.epa.gov/iris/. Last accessed August 26, 2003.

Hutter GM. 1993. Reference data sheet on sewer gas(es) (hydrogen sulfide, carbon dioxide, methane, ammonia, biological agents). Glenview, Illinois: Meridian Engineering & Technology. Available from URL: http://www.meridianeng.com/sewergas.html. Last accessed August 26, 2003.

McGavran P. 2001. Literature review of the health effects associated with the inhalation of hydrogen sulfide. Boise: Idaho Department of Environmental Quality. Available from URL: http://www.deq.state.id.us/air/hydrogensulfide_litreview.pdf. Last accessed August 26, 2003.

McSweeney H. 2003. Sewer gas study report, Mountain View study. July 15, 2003. [WDHFS] Wisconsin Department of Health and Family Services. 2002. Sewer gas. Madison: Wisconsin Department of Health and Family Services. Available from URL: http://www.dhfs.state.wi.us/eh/Air/fs/SewerGas.htm. Last accessed September 10, 2003.

[WHO] World Health Organization. 2003. Concise international chemical assessment document 53, hydrogen sulfide: human health aspects. Geneva, Switzerland: World Health Organization. Available from URL: http://www.who.int/pcs/cicad/full_text/cicad53.pdf. Last accessed August 26, 2003.


PREPARERS OF REPORT

Arizona Department of Health Services

Andrea Domanik, Office of Environmental Health


ATSDR Regional Representative

William Nelson
Office of Regional Operations, Region IX
Office of the Assistant Administrator


ATSDR Technical Project Officer

Gail Godfrey
Division of Health Assessment and Consultation
Superfund Site Assessment Branch
State Programs Section


APPENDIX A: MAP OF THE MOUNTAIN VIEW NEIGHBORHOOD

Map of the Mountain View Neighborhood


APPENDIX B:

HEALTH EFFECTS OF LOW-DOSE INHALATION OF HYDROGEN SULFIDE
Studies Contaminant Concentration/Exposure Period (ppm) Health Effects
Systemic
Respiratory
Bhambhani & Singh (1991) H2S 5
2.5
16 minutes, exercise Significant increase in O2 uptake
Respiratory exchange ratio decreased significantly
Bhambhani et al. (1994) H2S 5 30 minutes, exercise No effect
Bhambani et al. (1996) H2S 10 15 minutes, exercise No altered pulmonary function
Jappinen et al. (1990) H2S 2 30 minutes, exercise Indication of bronchial obstruction in 2 of 10 asthmatics
  H2S <10   No altered pulmonary function
Jaakkola et al. (1990) TRS 0.003 mean; 0.04 maximum 4-hour
0.001 mean; 0.02 maximum 4-hour
Significant increase in nasal symptoms, cough. Nonsignificant increase in breathlessness
Marttila et al. (1994) TRS 0.003 mean; 0.04 maximum Nonsignificant increase in nasal symptoms and cough in children
Marttila et al. (1995) TRS 0.007
0.007-0.02
>0.02
No effect
Significant nasal and pharyngeal irritation
Significant nasal and pharyngeal irritation
Haahtela et al. (1992) TRS 0.1 maximum 4-hour Increased respiratory symptoms
Partti-Pellinen et al. (1996) TRS Annual mean 0.002-0.003
24-hour average 0.0-0.04
1-hour maximum 0.1
Increased eye and nasal irritation, cough, breathlessness, headache
Increased eye and nasal irritation, cough, breathlessness, headache
Increased eye and nasal irritation, cough, breathlessness, headache
Cardiovascular
Bhambhani and Singh (1991) H2S 5 16 minutes, exercise No change in heart rate
Bhambhani et al. (1994) H2S 5 30 minutes, exercise No change in heart rate
Bhambhani et al. (1996b, 1997) H2S 5, 10 30 minutes, exercise Impaired anaerobic metabolism
Musculoskeletal
Bhambhani and Singh (1991) & Bhambhani et al. (1994, 1996a, 1996b, 1997) H2S 5, 10 30 minutes, exercise Minimal above-normal increases in blood lactate concentrations and changes in citrate synthetase indicating inhibition of the aerobic capacity of exercising muscle
Metabolic
Bhambhani and Singh (1991) H2S 5
2
16 minutes, exercise
16 minutes, exercise
Significant increase in blood lactate concentrations
No increase in blood lactate concentrations
Bhambhani et al. (1994, 1996b) H2S 5 30 minutes, exercise No significant increase in lactate concentration; decrease in muscle sythase in men
Bhambhani et al. (1997) H2S 10   Significant increases in blood lactate concentrations; no significant changes in muscle lactate dehydrogenase, citrate synthase, or cytochrome oxidase
Ocular
Haahtela et al (1992) H2S Maximum 4-hour 0.1, 24-hour average 0.03 Significant increases in eye symptoms
Marttilla et al. (1994, 1995) TRS 0.007
0.007-0.02
>0.02
No effect
Eye symptoms
Eye symptoms
Jaakkola et al. (1990) TRS Annual mean 0.004
Daily peak 0.07
Twelve times more eye irritation than people without exposure
Gastrointestinal
Haahtela et al. H2S Highest 4-hour 0.1, 24-hour average 0.03 Significant increases in nausea
Significant increases in nausea
Marttila et al. (1994, 1995) TRS 0.007
0.007-0.02
>0.02
Significant increase in nausea
Dermal
Tvedt et al (1991a, b) H2S 8-16 Peeling of facial skin of one patient
Neurological Effects
Gaitonde et al. (1987) H2S 0.6 1 year Ataxia, choreoathetosis, dystonia, inability to stand in one 20-month-old child
Haahtela et al. (1992) H2S Maximum 4-hour 0.1, 24-hour average 0.03 Significant increase in headache, mental symptoms
Marttila et al. (1994, 1995) TRS 0.007
0.007-0.02
>0.02
No effect
No effect
Nonsignificant increase in headaches
Bates et al. (1997, 1998) H2S Median 0.01, with 35% of measurements > 0.05 and 10% > 0.3 Significant increases in diseases of nervous system and sense organs
Reproductive Effects
Hemminki and Niemi (1982) H2S Annual mean 0.003 Nonsignificant increase in spontaneous abortion

TRS = Total reduced sulfur; complex mixture of hydrogen sulfide, methyl mercaptan, methyl sulfides from pulp mills. Hydrogen sulfide represents two thirds of the TRS. The ATSDR Toxicological Profile for Hydrogen Sulfide containing the studies referenced in Appendix B can be found at URL: http://www.atsdr.cdc.gov/toxprofiles/tp114.html.


APPENDIX C:

MOUNTAIN VIEW SEWER GAS ODOR SAMPLING SCHEDULE - JUNE 27, 2003 THROUGH JULY 15, 2003
Date Time Reporter Effects Reported*
Thursday, June 26, 2003 9:00 PM Resident  
Friday, June 27, 2003 9:20 AM Resident  
  9:55 PM Resident  
Saturday, June 28, 2003 9:20 AM Resident  
  8:52 PM Resident  
  10:00 PM Resident  
Sunday, June 29, 2003 9:10 PM Resident  
  10:00 PM Resident Homeowner ill for several days from sampling manholes with resident
  11:22 PM Resident  
Monday, June 30, 2003 9:00 AM Resident  
  11:40 AM Resident  
  9:30 PM Resident  
Tuesday, July 1, 2003 10:30 AM ADHS & resident  
  7:44 PM Resident  
  10:34 PM Resident  
Wednesday, July 2, 2003 5:00 AM ADHS Smelled gas, 30 feet from manhole #117 & 118; Indoor readings (homeowner)
  10:30 AM ADHS & resident Smelled gas 20 feet from manhole #414; Indoor readings (homeowner)
  8:05 PM Resident  
  9:00 PM ADHS & resident Indoor readings (homeowner)
Thursday, July 3, 2003 6:10 AM ADHS Indoor readings (homeowner)
  10:30 AM ADHS & resident Indoor readings (homeowner)
  8:00 PM ADHS & resident  
  11:30 PM Resident  
Friday, July 4, 2003 9:15 PM Resident  
Saturday, July 5, 2003 11:15 AM Resident  
  7:45 PM Resident  
  9:30 PM Resident  
  10:30 PM ADHS No meter, no gas smell
Sunday, July 6, 2003 12:26 AM Resident  
  10:00 PM Resident  
  10:30 PM ADHS No meter, no gas smell
Monday, July 7, 2003 12:05 AM Resident  
  12:50 AM Resident  
  9:25 PM ADHS & resident  
Tuesday, July 8, 2003 12:50 AM Resident  
  10:10 AM ADHS & resident  
  8:30 PM Resident  
Wednesday, July 9, 2003 12:20 AM Resident  
  10:30 AM ADHS & resident  
  10:00 PM ADHS & resident Smelled gas near manhole #414
  10:30 PM Resident  
Thursday, July 10, 2003 9:30 AM ADHS & resident  
  8:00 PM Resident  
  10:45 PM Resident  
Friday, July 11, 2003 11:00 AM ADHS & resident Smelled gas near manhole #117
  8:25 PM Resident  
Saturday, July 12, 2003 12:30 AM Resident  
  9:55 PM Resident  
Sunday, July 13, 2003 9:20 PM Resident  
Monday, July 14, 2003 12:40 AM Resident  
Tuesday, July 15, 2003 10:00 PM Resident  

*Table cells that are blank reflect that no effect was noted.


CERTIFICATION

This Mountain View Sewer Gas Study Health Consultation was prepared by the Arizona Department of Health Services under cooperative agreement with the Agency for Toxic Substances and Disease Registry. It is in accordance with approved methodology and procedures existing at the time the health consultation was initiated.

Gail Godfrey
Technical Project Officer
SPS, SSAB, DHAC


The Division of Health Assessment and Consultation (DHAC), ATSDR, has reviewed this health consultation and concurs with its findings.

Roberta Erlwein
Chief, SSAB, DHAC, ATSDR


1 Please consult the glossary at the beginning of the health consultation for definitions of terms and agency descriptions.


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