Carbonyl Sulfide Poisoning

Carbonyl Sulfide (COS) is a chemical consisting of carbon double bonded to oxygen and sulfur.

Carbonyl sulfide is a colorless, poisonous, flammable gas with a distinct sulfide odor. The gas is

toxic and narcotic in low concentrations and presents a moderate fire hazard. The largest man-

made sources of carbonyl sulfide release include its primary use as a chemical intermediate and

as a byproduct of carbon disulfide production; however, it is also released from automobiles,

coal-fired power plants, biomass combustion, fish processing, combustion of refuse and plastics,

petroleum manufacture, and manufacture of synthetic fibers, starch, and rubber.

The EPA lists Carbonyl Sulfide (COS) as a Hazardous Air Pollutant (HAP) and in the body or in

in the presence of moisture it combines to form Hydrogen Sulfide (H2S). Effects of carbonyl

sulfide on human health and the environment depend on how much carbonyl sulfide is present

and the length and frequency of exposure. Effects also depend on the health of a person or the

condition of the environment when exposure occurs.

COS, like H2S, is an odorous respiratory irritant. It is immediately metabolized to H2S in

humans. Animal studies have shown that COS and H2S have a similar dose-response for

some health effects, but little is known about the COS dose-response relationship for

respiratory exposures.

At levels greater than 50 ppm, COS effects in humans are similar to those from H2S. In the

absence of low-level COS exposure studies, ATSDR cannot determine what COS levels are

clearly safe. However, toxicological analogies are often drawn between similar chemicals. In

reviewing the existing toxicological data, it is reasonable to expect that COS effects are

qualitatively similar to the effects from H2S exposures, since COS is metabolized to H2S.

The National Oceanic and Atmospheric Administration (NOAA) Computer-Aided Management

of Emergency Operations Sheet (CAMEO) shows the following recommedations:

AEGLs (Acute Exposure Guideline Levels)

Interim AEGLs for Carbonyl sulfide (463-58-1)

Exposure Period AEGL-1 AEGL-2 AEGL-3

10 minutes NR 69 ppm 190 ppm

30 minutes NR 69 ppm 190 ppm

Interim AEGLs for Carbonyl sulfide (463-58-1)

Exposure Period AEGL-1 AEGL-2 AEGL-3

60 minutes NR 55 ppm 150 ppm

4 hours NR 34 ppm 95 ppm

8 hours NR 23 ppm 48 ppm

NR = Not recommended due to lack of warning properties

(NAC/NRC, 2011)

Excerpts from the Materials Safety Data Sheet for Carbonyl Sulfide reveal:

Irritating to the eyes, mucous membranes and respiratory system and is narcotic at high

concentrations. May decompose into hydrogen sulfide within body tissues resulting in

inhibition of cellular respiration, possible pulmonary paralysis, sudden collapse and

death. It is also highly flammable.

Continuous exposure to low (15-50 ppm) concentrations will generally cause irritation to

mucous membranes, and may also cause headache, dizziness or nausea. Other reported

effects include central nervous effects as well as giddiness, vertigo, amnesia, confusion,

weakness, and muscle cramps.

A 2007 ATSDR Health Consultation of a pulp and paper mill emitting Carbonyl Sulfide and

H2S in North Carolina gave the following recommended exposure limits:

Carbonyl Sulfide Air Quality Recommended Exposure Standards

(from various agencies or organizations)

Michigan, for example, set an annual air standard for carbonyl sulfide at just 9 μg/m3

(3.7 ppb).

As of 1994, there was limited information on the acute toxicity of carbonyl sulfide in humans

and in animals. High concentrations (>1000 ppm) can cause sudden collapse, convulsions, and

death from respiratory paralysis. Occasional fatalities have been reported, practically without

local irritation or olfactory warning. In tests with rats, 50% animals died when exposed to 1400

ppm of COS for 90 minutes or at 3000 ppm for 9 minutes. Limited studies with laboratory

animal studies also suggest that continued inhalation of low concentrations (approximately 50

ppm for up to 12 weeks) does not affect the lungs or the heart.

Imported Drywall –

http://www.atsdr.cdc.gov/drywall/docs/drywall_for_healthcare_providers.pdf

The U.S. Consumer Product Safety Commission (CPSC) has received 3,850 reports from

residents in 42 States, the District of Columbia, American Samoa, and Puerto Rico who believe

their health symptoms or the corrosion of certain metal components in their homes are related to

the presence of drywall produced in China. State and local health authorities also received

similar reports; some cases have been reported to regional Poison Control Centers.

The CPSC is leading the federal investigation. The Centers for Disease Control and Prevention

(CDC), the Agency for Toxic Substances and Disease Registry (ATSDR), the U.S.

Environmental Protection Agency (EPA), and the U.S. Department of Housing and Urban

Development (HUD) are providing technical support to CPSC and several state health

departments. The agencies are working to identify whether the drywall is emitting chemicals of

concern and whether homes containing the drywall pose any health risk to people who live in

them. This drywall was first imported to the U.S. and used to build or remodel homes from

2001–2008 and may still be in use. The number and location of all homes containing the

imported drywall is not known.

At this time, not enough information exists to determine the nature and magnitude of a potential

health risk. Likewise, we do not know if every home that contains this product is, or will be,

affected. This fact sheet provides information for healthcare providers about what we know.

What are residents reporting?

Common reports to the CPSC and state health departments from residents who live in homes

believed to contain problem drywall include one or more of the following:

Issues related to indoor air

a rotten egg smell or smell of matches or fireworks in ••their homes

Issues related to metal inside homes

blackened and corroded metal components in their ••homes and frequent replacement of metal

components in air conditioning units

Health symptoms (some symptoms are also consistent with other indoor air quality problems)

irritated and itchy eyes and skin••

difficulty breathing ••

nasal irritation••

recurrent headaches••

sinus infection••

exacerbation of asthma••

What chemicals have been found?

CPSC indoor air test results have found low parts per-billion (ppb) levels of reactive sulfur gases

including hydrogen sulfide and carbonyl sulfide. The gases are higher in homes that contain

imported drywall than those that do not. All of the levels were far lower than levels related to

health effects.

CPSC drywall off-gassing studies show higher emissions of reactive sulfur gases in imported

drywall than drywall manufactured in the U.S. Emission rates were highest for hydrogen sulfide,

followed by sulfur dioxide. The same trend holds true for volatile sulfur compounds. CPSC is

using computer modeling to convert the emission test results to predict the estimate levels in

indoor air.

Many sulfur-based compounds occur naturally in the environment, such as in swamps. Paper

mills, the textile industry, petroleum and natural gas extraction, and other industries produce

these gases as waste products. Cigarette smoke, septic tanks, wastewater treatment, and

automobiles also emit these compounds.

Other compounds that are typically present in indoor air were found in both homes that contain

imported drywall and homes that do not. Sources of these compounds include new carpeting and

furniture, pressed plywood and particle board, glues, paints, and cooking.

What health problems can be caused by exposure?

Sulfur gases are colorless and have an unpleasant odor, often described as smelling like a rotten

egg. Residents also report smells similar to fireworks or striking a match. Most people can smell

these chemicals at levels below those known to cause adverse health effects. However, some

people react more strongly to noxious odors. Exposure to high levels of sulfur-containing

compounds can cause olfactory fatigue. That is, the olfactory sensing cells in the nose become

saturated and no longer signal the brain that the substance is present. When this occurs, people

can no longer smell the substance even though it is present in the air.

Exposure to reactive sulfur gases may result in eye, nose, and throat irritation and exacerbation

of respiratory problems. Less is known about chronic exposure to lower levels (1-30 ppb), such

as those found in the limited indoor testing conducted in homes reported to contain imported

drywall.

Short term exposure (hours) to low concentrations of sulfur gas can result in the following

symptoms:

eye irritation ••

sore throat ••

stuffy nose/rhinitis ••

cough ••

shortness of breath/chest pain ••

nausea ••

headaches ••

Chronic exposure (days to years) to low concentrations can result in the following additional

symptoms:

fatigue ••

loss of appetite ••

irritability ••

poor memory ••

dizziness ••

insomnia ••

headaches ••

Other sources of indoor contamination may result in similar symptoms.

Who is at risk?

The most sensitive populations include:

patients with asthma ••

patients with chronic obstructive pulmonary ••disease (COPD),

the elderly, and ••

young children with compromised respiratory function. ••

What should I tell my patients?

Symptoms of exposure to reactive sulfur compounds are non-specific. A patient may have

symptoms that include:

watery eyes with redness and/or itching, ••

increased episodes of nasal congestion or coughing, and ••

difficulty breathing or shortness of breath. ••

Patients may report subsiding of symptoms when they are away from their homes. If the

patient is experiencing symptoms of exposure the person attributes to drywall, you can advise

the patient to take the following actions:

If the odor is strong inside the home, go outside to breathe ••fresh air for immediate relief.

If possible, avoid areas where the odor is present. ••

Avoid heavy exercise indoors.••

EPA test results show warm and humid conditions result in higher levels of contaminants in

the air. Patients should be encouraged to run air conditioning systems and dehumidifiers as

much as feasible. We do not yet know whether opening windows to allow fresh air to come

into the home is beneficial.

For patients with chronic respiratory medical conditions (such as asthma or COPD):

Be sure the patient understands that breathing sulfur gas ••can aggravate a medical condition.

Advise the patient to keep inhalers and/or eye drops ••readily available for use, if needed.

Encourage patients to contact the CPSC (number below) and their state or local health

departments to report the problem.

What other problems should patients watch for in their home that may be related to this

drywall? Exposed metal wiring has been damaged in some homes with this drywall. The CPSC is

investigating the possibility that fires may occur related to this corrosion. The CPSC is also

investigating to determine whether smoke and carbon monoxide detectors are being damaged.

People experiencing unusual electrical problems (such as malfunctioning appliances or light

switches) should contact a licensed electrician.

Carbonyl sulfide decomposes in the presence of humidity and bases to carbon dioxide and

hydrogen sulfide so the recommended standards for H2S are shown below:

Hydrogen Sulfide Air Quality Recommended Exposure Standards

(from various agencies or organizations)

Map Distribution

U.S. Carbonyl Sulfide Toxic Release Sites

Toxic Release Inventory Sites in Ashtabula Ohio

In Ashtabula Ohio, the Millennium Inorganic Cristal Chemical Company, (established in 1985)

has been emitting millions of pounds of Carbonyl Sulfide. Carbonyl Sulfide (COS) releases at

more than 5 million pounds per year makes these plants the 1st and 3rd

highest emissions of COS

in the country.

Toxic Releases from Millenium (Plant 1) in 2010

Toxic Releases from Millenium (Plant 2) in 2010

For the two plants together, Carbonyl Sulfide emissions were over 4.5 million pounds in 2010

and over 5 million pounds per year in 2003 the year after the subject moved into the area.

Historical Toxic Releases from Millenium (PLANT 1) 1988 -2010

Historical Toxic Releases from Millenium (PLANT 2) 1988 -2010

As shown by the map above, Millennium Inorganic Chemicals in Ashtabula are the two largest

releases of manganese in the country. The release of more than 5 million pounds of manganese

per year into on-site landfills is more than 10 times the amount of manganese released by any

other facility.

In addition to average emissions, there were also frequent transient events which could have

made the pollution levels even worse than reported. Ohio EPA frequently cited Millennium for

exceeding emissions permits as a result of the use of a safety valve to bypass the emissions unit’s

air pollution control equipment. The company exceeded the limit for CO of 12.7 pounds per hour

in 38 malfunction incidents in less than 5 years and agreed to pay a penalty of more than

$100,000 for the violations.

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