EPA Chemical Descriptions

Ammonia

Ammonia is a primary eye and upper respiratory tract irritant.

An unpublished study conducted by the Detroit Department of Health and cited by the American Conference of Governmental Industrial Hygienists (ACGIH) (1986/Ex. 1-3, p. 27) reports that ammonia concentrations in the range of 20 to 25 parts per million (ppm) elicited complaints of discomfort from workers engaged in blueprinting and copying operations. In addition, a study of pigs conducted by Stombaugh et al. (1969) appeared to demonstrate that exposure to ammonia also causes systemic effects. Thus the ACGIH established both an 8-hour standard of 25 ppm to protect against chronic effects and a 35-ppm short-term standard to protect against ammonia’s irritant effects. OSHA has recently reduce the “dangerous” level from 500 ppm to 300 ppm.

A high alarm level of 100 ppm has been established at the refinery fenceline, and a low alarm level of 3 ppm. Typically, the maximum daily concentrations at the ConocoPhillips-Rodeo refinery fenceline are below 0.05 ppm.

Benzene

Benzene is a problem because it is known human carcinogenic. Benzene is common in most gasoline used in the United States, and there could be a quart of Benzene in your gas tank right now. Because of this, Benzene is present in the air in most areas in the United States.

It is regulated at sources by EPA as one of the 161 hazardous air pollutants (HAPs) and it is one of 33 Urban Air Toxics that are priorities for EPA. In most cities, it is one of the top three carcinogens in the air. Levels have dropped throughout the US over the last decade, but concentrations of about 1 part per million are common in metropolitan areas. Benzene is one of the worst of the hazardous air pollutants (HAPs) that USEPA regulates in terms of its health effects. There are no standards set by EPA for this chemical; it is regulated by emission permits at major sources. OSHA recently reduced the dangerous level from 3000 ppm to 500 ppm.

Butane

The problem with butane isn’t so much that it’s toxic, but that it’s explosive at high concentrations. It may also be an indicator of problems that are occurring at the ConocoPhillips-Rodeo refinery if other chemicals are being released that may be more toxic than butane and that may not be measured by the monitors at the fenceline.

The high alarm level set by the community is about one-tenth of what would be necessary to start a fire (1,000 parts per million, ppm), and the low alarm level (800 ppm) is set to provide an early warning that levels are increasing.

The low alarm level has no health significance, but it is the “safe” level used by the National Institute for Occupational Safety and Health (NIOSH). The primary risk of exposure to butane is narcosis, which occurs at high exposure levels. Exposure to 10,000 ppm butane for 10 minutes causes drowsiness, but there are no reports of systemic toxicity or irritation at this level (Gerarde 1963a, as cited in American Conference of Governmental Industrial Hygienists [ACGIH] 1986/Ex. 1-3, p. 10).
In most cities in the United States, butane is not detected very frequently.

Along the perimeter of the ConocoPhillips-Rodeo refinery, levels at the north fenceline are usually higher than those at the south fenceline. But levels are usually below 1 ppm.

Butadiene (1, 3)

This chemical is suspected of causing cancer in people. Much of it comes from cars and trucks burning gasoline. It is a problem in most major Cities in the country, and in addition to benzene, and formaldehyde is a top three contributor to the cancer risk caused by hazardous air pollutants (HAPs).

It is regulated at sources by EPA as one of the 161 hazardous air pollutants (HAPs) and it is one of 33 Urban Air Toxics that are priorities for EPA. The short-term toxicity of this chemical is low, and it is used primarily in tire-making. The safe level is related to the lower level that would cause explosions, which is 20,000 ppm

Carbon Monoxide

Carbon monoxide is a colorless and odorless gas that blocks your blood’s ability to carry oxygen. Because of this, carbon monoxide exposure can be fatal at high doses. Various organizations have set acceptable upper limits for humans. People can breathe higher amounts for shorter times without a harmful effect, but people with heart or lung diseases will be more susceptible to poisoning.

The U.S. Environmental Protection Agency (EPA) says that 35 parts per million (ppm) is safe for short periods, and that 1,000 ppm is cause for immediate evacuation of the area. Most home carbon monoxide alarms will start to go-off at about 100 ppm. EPA expects that levels of 9 ppm will be safe over the long term. The average level for most large cities is about 1 ppm.

At the ConocoPhillips-Rodeo refinery, the maximum levels each month are about 1 ppm, which is about the same as in most cities in the United States. People who smoke cigarettes get carbon monoxide from the smoke, and they average about 35 ppm in their blood. Because of this, they could be affected by lower levels in the air than nonsmokers.

Carbon Disulfide

Carbon Disulfide is used in the rubber and rayon industries and is a highly toxic chemical that causes a wide variety of neurological symptoms from headache and dizziness to psychotic–like states. It is regulated at sources by EPA as one of the 161 hazardous air pollutants (HAPs).

Health effects on people have been reported at lower concentrations than previously reported in animals, and health effects include cardiovascular damage as well as reproductive injuries to the developing fetus. Long-term safe levels have been lowered to 1 ppm, with exposure to 10 ppm for only very short periods (ACGIH and NIOSH), and short-term levels that could potentially be fatal would be around 500 ppm. In addition to evidence that carbon disulfide is a cardiovascular toxin, there is a substantial body of evidence that exposure to carbon disulfide presents a fetotoxic hazard and that this substance may also be a teratogen. Some of the early (pre-1977) animal data on reproductive effects were reviewed in the NIOSH (1977b/Ex. 1-260) criteria document on carbon disulfide. In its post hearing submission, NIOSH (Ex. 193) mentions two relevant reports. One by Cai and Bao (1981, as cited in Ex. 193) reported increased incidences of menstrual disturbances and of pregnancy toxemia, a potentially lethal condition, in rayon workers. These authors also presented evidence that CS(2) can cross the placental barrier and be secreted into mothers' milk. The second report cited by NIOSH (Hemminki and Niemi 1982, as cited in Ex. 193) found a significantly elevated incidence of spontaneous abortions among women employed in viscose rayon facilities in Finland; however, data on the specific CS(2) exposure levels were generally lacking.

Carbonyl Sulfide

This chemical gets converted to hydrogen sulfide in your blood. Hydrogen sulfide causes many of the same symptoms as carbon monoxide because it works the same way. It also binds to the oxygen-carrying pigment in blood (called hemoglobin) and, like carbon monoxide, prevents hemoglobin from carrying oxygen around the body. It is regulated at sources by EPA as one of the 161 hazardous air pollutants (HAPs).

There are no U.S. Environmental Protection Agency (EPA) standards for carbonyl sulfide or hydrogen sulfide in the air outside, but the National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA) think 10 parts per million (ppm) is safe for short periods, while 100 ppm is considered very dangerous.

The 1986 American Conference of Governmental Industrial Hygienists (ACGIH) documentation (Ex. 1-3, p. 318) cites several reports (Brieger 1964; Kranenburg and Kessener 1935; Masure 1950; Elkins 1950a/Ex. 1-953) on the occurrence of adverse ocular effects, including conjunctivitis, associated with exposure to 20 ppm or less of hydrogen sulfide. A study by Poda and Aiken (1966/Ex. 1-115) reported that the adoption of a voluntary limit of 10 ppm in two heavy-water plants eliminated exposure problems. An early study by Flury and Zernik (1931f, as cited in ACGIH 1986/Ex. 1-3, p. 318) reported that conjunctivitis was caused by exposure to 10 to 15 ppm of hydrogen sulfide for 6 hours endured for several days; however, OSHA is unaware of cases in which this substance caused irreversible eye damage. NIOSH relied essentially on the studies discussed above (Poda and Aiken 1966/Ex. 1-115; Flury and Zernik 1931f, as cited in ACGIH 1986/Ex. 1-3, p. 318) when recommending its limit for hydrogen sulfide of 10 ppm for 10 minutes; NIOSH (Ex. 8-47, Table N7) continues to recommend this ceiling for hydrogen sulfide.

Along the fenceline of the Conoco-Phillip refinery, carbonyl sulfide is rarely detected by the FTIR monitors. Additionally, this chemical decomposes to hydrogen sulfide, which has an odor threshold that is well below the alarm setting. (See the FAQ on What are odor thresholds?)

Ethane

The problem with ethane isn’t so much that it’s toxic, but that it’s explosive at high concentrations. It may also be an indicator of problems that are occurring at the Conoco-Phillips-Rodeo refinery if other chemicals are being released that may be more toxic than ethane and that may not be measured by the monitors at the fenceline.

Ethane is the second ingredient in natural gas besides methane, and like methane it is of very low direct toxicity, but it will explode at concentrations above 30,000 ppm.

Ethyl Benzene

Ethyl benzene is of low acute toxicity in general, but at high levels it can produce the same narcotic-like symptoms of benzene and toluene. It is regulated at sources by EPA as one of the 161 hazardous air pollutants (HAPs).

Long-term safe levels have been set at 100 ppm, while levels above 800 ppm are dangerous even in the short-term. The chemical causes respiratory system irritation (eyes, nose, lungs) and a swelling of the lungs that at high levels can be life threatening. Ethyl benzene is also flammable above 1,000 ppm, but health effects are more important. OSHA concludes that workers exposed to concentrations of ethyl benzene above the 100-ppm level, even briefly, are at significant risk of experiencing irritation; the Agency considers this to be a material impairment of health. Accordingly, the Agency is establishing a short-term limit of 125 ppm for a 15-minute period to supplement the existing 100-ppm time-weighted-average limit for ethyl benzene.

Ethylene

Ethylene is a flammable gas that can cause explosions at levels above 25,000 ppm, and can also behave as an anesthetic at those levels. At low levels it is not very toxic, but it can react with a wide variety of other chemicals to produce more toxic products.

Hexane

Hexane is another component of gasoline that acts as a respiratory tract irritant at low concentrations and a narcotic anesthetic at higher concentration. There are physiologic similarities between hexane and carbon disulfide in the mechanism of toxicity.

Safe exposures are below a threshold between 50 ppm (ACGIH) and 500 ppm (OSHA). Levels above 5000 ppm were considered dangerous, but the danger level has been reduced to acknowledge that Hexane may be explosive above 11,000 ppm., and are now set at 1100 ppm.

Hydrogen Sulfide

Like Hydrogen cyanide, hydrogen sulfide is a dangerous poison at low concentrations. Sometimes known as sewer gas, hydrogen sulfide smells like rotten eggs, and begins to cause eye and respiratory irritation at concentrations above 20-30 ppm. Prolonged exposure to concentrations of 250 ppm will cause lung congestion and pneumonia-like symptoms, while concentrations above 1000 ppm will be fatal.

OSHA concludes that the former 20-ppm (10-minute) short-term limit and 50-ppm ceiling limit did not adequately protect workers against the adverse ocular effects associated with exposure to concentrations of hydrogen sulfide below 20 ppm, as reported in several studies. OSHA finds that the eye irritation and conjunctivitis associated with such exposures represent a significant risk of material health impairment to workers, who may be forced to seek medical treatment after such exposure and who may also be unable to work during the period of recovery. OSHA has accordingly established an 8-hour TWA limit for hydrogen sulfide of 10 ppm and a short-term limit of 15 ppm. These levels have been demonstrated to be effective in preventing irritation and conjunctivitis in the workplace (Poda and Aiken 1966/ Ex. 1-115). The Agency finds that this dual limit will provide protection both in continuous steady-state exposure situations and in those characterized by sharp peaks and will do so more effectively than a single, short-term limit such as that recommended by NIOSH.

Methane

The problem with methane isn’t so much that it’s toxic, but that, like butane, it’s explosive at high concentrations. The high alarm level set by the community is about one-tenth of what would be necessary to start a fire (5000 parts per million [ppm]), and the low alarm level (1000 ppm) is set to raise an early warning that levels are rising. The low alarm level has no health significance.

In most cities in the United States, methane is detected frequently. Typically levels are below 1 ppm, except near landfills and some wetlands. Along the perimeter of the ConocoPhillips-Rodeo refinery, levels at the north fenceline are usually slightly higher than at the south fenceline, but levels are usually below 2 ppm.

Methyl Mercaptan

Methyl mercaptan smells like rotten eggs and is a highly toxic chemical. It acts on the respiratory center, producing death by respiratory paralysis.

DeRekowski (1893, as cited in ACGIH 1986/Ex. 1-3, p. 405) and Frankel (1927/Ex. 1-1033) have reported that the acute toxicity of methyl mercaptan is similar to but somewhat lower than that of hydrogen sulfide; however, Ljunggren and Norberg (1943/Ex. 1-916) have concluded that the two substances exhibit toxicities of the same magnitude. Pulmonary edema results from exposures to lower, less acute concentrations of methyl mercaptan (Fairchild, personal communication, as cited in ACGIH 1986/Ex. 1-3, p. 405). NIOSH (Ex. 8-47, Table N7) recommends a ceiling limit at the same 0.5 ppm level. OSHA is revising its limit for methyl mercaptan to 0.5 ppm as an 8-hour TWA. Levels above 150 ppm are considered immediately dangerous.

Methyl Tert-Butyl Ether (MTBE)

This chemical, often abbreviated MTBE, is added to gasoline to make it burn cleaner. The problem is, spills and leaks from underground gas tanks have contaminated the water supply of some communities. Information on human exposure to MTBE is limited. It is regulated at sources by EPA as one of the 161 hazardous air pollutants (HAPs).

Humans are acutely exposed to MTBE as a part of a medical treatment to dissolve cholesterol gallstones (Thistle, 1992). Injection of the gall bladder with a high dose of MTBE can be associated with several types of health effects (e.g., nausea, vomiting, sleepiness). Minor transient mucosal damage in the gallbladder has been demonstrated with extensive exposure, but no clinically significant consequences have been reported. One patient has been reported to develop intra vascular hemolysis and renal failure following inadvertent extravasation of a large bolus of MTBE (Ponchon et al., 1988). Reliable data from epidemiology studies of human exposure to airborne MTBE are not currently available. Rats exposed to 400 parts per million (ppm) for long periods exhibited no adverse health effects.

The alarm levels set by the community are early indicators of potential health problems. The low alarm level is 40 ppm and the high alarm level is 200 ppm. Along the perimeter of the ConocoPhillips-Rodeo refinery, typical annual peaks are about 0.1 ppm.

Naphthalene

Naphthalene was formerly used in mothballs as an insecticide whose odor is familiar to everyone. It is regulated at sources by EPA as one of the 161 hazardous air pollutants (HAPs). Safe levels have been given as 10 ppm (ACGIH) while levels above 500 ppm were considered dangerous, but this has recently been reduced to 250ppm.

Naphthalene is a general irritant, but since naphthalene is a solid at room temperature, poisoning is usually not caused by breathing vapors, but by accidentally eating or drinking, or in industrial accidents. In the final rule, the OSHA is retaining the 8-hour TWA of 10 ppm and adding a 15-minute STEL of 15 ppm for naphthalene. This STEL is designed to protect against the eye irritation observed in workers at elevated levels (Robbins 1951/Ex. 1-799). The Agency concludes that these limits will protect workers from the significant risks of eye irritation and serious ocular effects, which constitute material health impairments that are potentially associated with exposure to levels above the 8-hour limit.

Nitrous Oxide

Oxides of nitrogen are formed anytime something is burned. Most of it comes from burning gas in cars and trucks or from power plants burning coal or natural gas to make electricity. Nitrous oxide is included in the “Oxides of Nitrogen” group that is one of the EPA Criteria pollutants.

Nitrous oxides irritate your lungs and can cause a number of health problems. This oxide of nitrogen is much less dangerous than nitrogen dioxide, which is a major problem in many U.S. cities. Nitrous oxide is sometimes called laughing gas and is used in the dental profession as an anesthetic. It is measured along the perimeter of the ConocoPhillips-Rodeo facility as an early indicator that something wrong has occurred at the refinery. The warning levels are set at 999 parts per million (ppm). Peak levels at the north fenceline are around 1 ppm, with about half of that also present at the south fenceline.

Octane

Octane is famous for being a component of gasoline (the octane rating). It is an eye and respiratory tract irritant, but at higher levels it acts like a narcotic anesthetic.

Safe long-term exposures are below 300-500 ppm ( 300, ACGIH,NIOSH, 500 OSHA), and the narcotic effects take place at about 10,000 ppm, which is also the point where levels are high enough to be explosive.

Flury and Zernik (1931h, as cited in ACGIH l986/Ex.l-3, p. 448) believed the narcotic concentration in humans to be 5000 ppm; Patty and Yant (1929, as cited in ACGIH 1986/Ex. 1-3, p. 448) placed the narcotic concentration at 8000 ppm. Recently, OSHA is revising its limits for octane to 300 ppm as an 8-hour TWA and 375 ppm as a 15-minute STEL. The Agency concludes that these limits will protect workers from the significant risks of narcosis, a material health impairment that is associated with octane exposures. Levels above 1000 ppm are now considered immediately dangerous because of the explosive potential at 10,000 ppm.

Ozone

Ozone is one of the ingredients in smog. When it’s in the upper atmosphere, ozone is beneficial because it protects us from dangerous ultraviolet light. Ozone is one of the 6 EPA criteria pollutants for which there is a enforceable upper limit.

In the lower atmosphere, ozone is highly injurious at concentrations as low as a few parts per million (Stokinger 1957/Ex. 1-97). A study in which young mice were exposed to 1 ppm ozone for 1 or 2 days reported damage to alveolar tissue (Bils 1970/Ex. 1-58). Human populations chronically exposed to lower concentrations of ozone have been observed to have changes in lung function. In one study, human volunteers exposed to 0.5 ppm ozone for 3 hours per day, 6 days per week, over 12 weeks showed significant changes in lung function (Jaffe 1967/Ex. 1-101). Other investigators reported a 20-percent reduction in timed vital capacity in persons exposed to average concentrations of ozone of 1.5 ppm (range not indicated) for 2 hours (Griswold, Chambers, and Motley 1957/Ex. 1-128). Welders exposed to maximal ozone concentrations of 9 ppm were observed to have pulmonary congestion (Kleinfeld and Giel 1956/Ex. 1-120). The maximum allowed by law in workplaces is 5 ppm. People with poor diets (low in antioxidants) or poor health may be predisposed to injury at lower concentrations than healthy people.

Most cities have problems with ozone; however, it now rarely exceeds 0.15 ppm. Cities are now moving toward an 0.08 ppm 8-hour EPA standard, which many of them exceed on days favorable for ozone formation (hot and sunny). Along the perimeter of the ConocoPhillips-Rodeo refinery, conditions at the north fenceline are about typical for what would be expected for a large municipality. The peak levels at the south fenceline are generally higher.

Propane

Propane isn’t a problem because of its toxicity, but again it is explosive like methane, ethane, and butane. Safe exposure levels are below 800 ppm, but you can’t smell it until the concentration is higher, around 5000 ppm. It is explosive above 20,000 ppm, and is classified as immediately dangerous within 10% of the explosive level.

Sulfur Dioxide

Sulfur Dioxide is included in the “Oxides of Sulfur” category that EPA regulates throughout the country. EPA has set a standard of 30 parts per billion (ppb) that is sufficiently low as to be safe for long term exposure. Most sulfur dioxide is created by burning fossil fuels containing trace amounts of sulfur. Burning coal for electric power generation is a major source, as well as cars and trucks. Sulfur dioxide is a lung irritant, and the swelling caused by breathing it will aggravate other lung conditions like asthma. The health effects of sulfur dioxide are reversible, in the sense that when the concentrations drop, the health effects go away too. Most cities show 24-hour averages in the 10-20 ppb range, with daily spikes several times higher. ADD FENCELINE DATA

Toluene

Toluene is a common organic solvent that is similar in toxicity to benzene.

It is regulated at sources by EPA as one of the 161 hazardous air pollutants (HAPs). At high concentrations it causes a narcotic anesthesia starting around 200 ppm in air, while levels above 10,000 ppm can be fatal. Safe levels are below 100 ppm. Long-term exposures are less dangerous than benzene in that toluene is not now suspected to be carcinogenic in humans. The acute toxicity of toluene in animals is however, greater than that of benzene.

Patty (1963b, as cited in ACGIH 1986/Ex. 1-3, p. 578) reports that the lethal doses of toluene and benzene in mice are 10,000 and 14,000 ppm, respectively. The oral LD(50) for toluene in rats is 7.53 ml/kg (Smyth, Carpenter, Weil et al. 1969/Ex. 1-442). Exposure of rats to 2500 or 5000 ppm of toluene caused a temporary decrease in white cell count but no evidence of damage to the blood-forming organs or the liver. Fairhall (1957d, as cited in ACGIH 1986/Ex. 1-3, p. 578) stated that severe toluene exposure can cause a marked drop in the red blood cell count and partial destruction of the blood-forming elements of the bone marrow, but other researchers report that numerous animal studies indicate that toluene is not a bone marrow toxin (Gerarde 1960c, as cited in ACGIH 1986/Ex. 1-3, p. 578). A study by Greenberg, Mayers, Heinmann, and Moskowitz (1942/Ex. 1-325) reported that painters exposed to toluene levels of 100 to 1100 ppm exhibited enlarged livers, a moderate decrease in red blood cell counts, enlarged red blood cells, and absolute lymphocytosis, but no leukopenia. Wilson (1943/Ex. 1-403) observed 1,000 workers exposed to toluene at levels ranging from 50 ppm to 1500 ppm for periods of one to three weeks. One hundred of these workers developed symptoms severe enough to require hospitalization. Levels of 500 ppm are considered immediately dangerous.

Trichloroethane (TCE) (1, 1, 1)

Trichloroethane is a widely used solvent that has contaminated ground water in many parts of the country. It is regulated at sources by EPA as one of the 161 hazardous air pollutants (HAPs) and it is one of 33 Urban Air Toxics that are priorities for EPA. Safe levels are below 50 ppm (ACGIH), but there is evidence that TCE is carcinogenic in animals, and hence, there may be no safe level. For short-term exposures 1000 ppm is considered immediately dangerous.

Xylenes (O, M, P)

There are three different forms of xylene (ortho, meta, para) that have similar toxicities. Xylene is a common liquid organic solvent, and is a natural component in gasoline. It is regulated at sources by EPA as one of the 161 hazardous air pollutants (HAPs). Safe long-term levels are 100ppm, although even short-term exposures above 1000 ppm are considered dangerous.

Xylenes cause a wide variety of health effects from neurological (dizziness, drowsiness, nausea or headache) to eye, nose and throat irritation, to skin irritation. Studies of workers exposed to xylene revealed headache, fatigue, lassitude, irritability, and gastrointestinal disturbances as the most common symptoms (Gerarde 1960d/Ex. 1-738a). At unspecified exposure levels, Browning (1965b/Ex. 1-1016) also noted gastrointestinal disturbances, in addition to kidney, heart, liver, and neurological damage; blood dyscrasias, some of which resulted in death, were also reported in these workers. A study by Nelson, Enge, Ross et al. (1943/Ex. 1-66), in which human volunteers were exposed to 200 ppm xylene, found eye, nose, and throat irritation in the subjects at this level of exposure .Levels of 900 ppm are considered immediately dangerous.

Total Hydrocarbons

To be determined

Source: Dan Petersen, EPA