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Butyl acrylate
Małgorzata Kupczewska-Dobecka
Butyl acrylate is a clear, flammable liquid with a fruity, pungent odor. Butyl acrylate is used in the preparation of polymers and copolymers with acrylic acid and its derivatives, methyl acrylate, vinyl chloride, butadiene, styrene.
Butyl acrylate is a skin, ocular, and respiratory tract irritant in animals. It can cause skin sensitization.
The International Agency for Research on Cancer (IARC) has classified butyl acrylate as a Group 3 carcinogen: not classifiable as to carcinogenicity to humans. There have been very little published data on the effects of butyl acrylate on humans. As with laboratory animal testing, sensitization and cross-sensitization with other acrylates has been reported in humans.
In the inhalation subchronic study on Sprague-Dawley rats the concentration 86 mg/m³ was identified as the no-observed-adverse-effect level (NOAEL).
Based on this data the Expert Group for Chemical Agents has established an 8-hour MAC (TWA) value of 11 mg/m³, and a MAC (STEL) value of 30 mg/m³.
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Methylcyclohexane
Roman Knapek
Methylcyclohexane (MCH) is a colorless combusible liquid with a poor benzene-like odour. MCH is used in organic synthesis and as a solvent for cellulose ethers.
The inhalation tract is the main exposed organ. MCH is less toxic but in high concentration it can cause headache, nausea, sleepiness and confusion, MCH can irritate the eyes. Its vapor can irritate the mucosis of the nose and pharynx. No carcinogenic, mutagenic, embriotoxic, fetotoxic and teratogenic effects have been found is the relevant toxicological studies.
In a subchronic inhalation study on rabbits the non-effective concentration was 4460 mg/m³, and an effective concentration was 11500 mg/m³.
The proposed maximum exposure limit MAC (TWA) of 1600 mg/m³ is based on the LOAEL value from a subchronic inhalation study on rabbits. The MAC (STEL) value is based on the irritative effect and 3000 mg/m³ is proposed.
There are no data for recommending a BEI value.
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Methylcyclohexanol
Grażyna Lebrecht, Sławomir Czerczak
Methylcyclohexanol is a colorless liquid with an aromatic odor. It appears as a mixture of three isomers (orta, meta, para). Methylcyclohexanol is primarily used as a solvent for resins, oils, waxes, lacquers, and also as a component of mixtures used in manufacturing soap and detergents.
Methylcyclohexanol can be absorbed into the body by inhalation of its vapors, by ingestion, and through the skin. Exposure to vapors may result in irritation of the ocular and upper respiratory mucous membranes.
The LD50 for rats (oral) is 1660 mg/kg, what indicates that the substance is harmful.
Limited data are available to estimate the toxicity of methylcyclohexanol for humans. In animal studies the lowest observed concentration which caused microscopic tissue changes in the liver and kidneys (LOAEL) was 565 mg/m³.
The MAC (TWA) value of 70 mg/m³ was established on the basis of the LOAEL value (565 mg/m³) and relevant uncertainty factors; the MAC (STEL) value has not been established due to insufficient data.
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2-Methylpentane-2,4-diol
Krystyna Sitarek
2-Methylpentane-2,4-diol is a liquid with a sweetish odour. It is used as a solvent and a semiproduct in obtaining cosmetics and drugs. 2-Methylpentane-2,4-diol has a relatively low toxicity.
The oral LD50 value for rats is 4.79 mg/kg b.w. It irritates the eyes and the mucous membranes of the respiratory tract.
2-Methylpentane-2,4-diol is not mutagenic.
The ceiling limit value MAC (C) 120 mg/m³ is recommended based on its very quickly irritative effect on the respiratory tract.
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Isobutyl acetate
Andrzej Sapota, Małgorzata Skrzypińska-Gawrysiak
Isobutyl acetate is mainly used as a solvent of nitrocellulose, oil varnishes, diluents, lakes and lacquers. Furthermore, it is used as an odorant, perfume component and in the production of drugs. It is also found in nature in fruit (raspberries, pears, apples, pineapples). Data on the production of isobutyl acetate are fragmentary. In 1984 its production in the USA was 38,000 ton.
Occupational exposure to isobutyl acetate takes place through inhalation and dermal contact during the production and application of this compound. There are no data concerning toxic effect of this compound on humans.
On the basis of the result of studies on laboratory animals, isobutyl acetate was found to have an irritating action on the eyes and the upper airways mucosa. Moreover, isobutyl acetate in small concentration demonstrated weaker irritating action than n-butyl acetate. In in vitro studies this compound did not show a mutagenic effect. There are no reports on other late outcome effects.
The RD50 (respiratory dose 50) value in mice, which is 3,890 mg/m³ may be accepted as a base for establishing an isobutyl acetate MAC (TWA) value. It is assumed that for compounds with an irritating action, MAC (TWA) values should be from 1/10 to 1/100 RD50 According to the recommendations of American hygienists, who suggest that the MAC (TWA) value should be 1/30 RD50, it was calculated that this concentration should be 130 mg/m³. However, considering that RD50 value is the only one that makes it possible to determine a MAC (TWA) value and also comparing existing RD50 values for other acetic acid esters with their MAC (TWA) values in Poland, the authors think that the value calculated in such a way for isobutyl acetate is too low.
Thus, we suggest accepting – by analogy to n-butyl acetate (and in accordance with standard values for the majority of other acetates of similar strength of irritating action) – 200 mg/m³ as a MAC (TWA) value for isobutyl acetate and 400 mg/m³ as a MAC (STEL) value of isobutyl acetate on the basis of the irritating action of the compound.
There is no basis for establishing a BEI value for isobutyl acetate.
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Piperazine
Andrzej Starek
Piperazine (CAS Registry No. 110-85-0) is a solid, crystalline substance used mainly as an antihelminthic drug in medicine and veterinary medicine, and also as corrosion inhibitor and polymerization accelerant in industry.
Piperazine is a low-toxic chemical. In humans, exposure to piperazine led to both skin sensitization and allergic asthma. No mutagenic and carcinogenic effects have been found in the relevant epidemiologic and experimental studies.
On the of human observations in industry, values of 0.1 mg/m³ and 0.3 mg/m³, have been proposed as MAC (TWA) and MAC (STEL) respectively.
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Propane
Jerzy P. Piotrowski, Jadwiga Szamańska
Propane is a colourless, extremely flammable gas obtained from lower boiling-point fractions of crude oil, or natural gas. It is used as fuel gas, often in combination with butane. At high concentrations, propane has a vapid smell.
Propane may cause acute poisoning as a result of emergencies in the workplace or at home. At high concentrations, it is asphyxiating and depressive to the central nervous system (CNS).
Short-lasting exposure to propane at concentrations below 18 000 mg/m³ do not cause any effects in humans, while in people exposed to concentrations as high as 180 000 mg/m³ it may produce vertigo. Liquid propane splashed on the skin causes skin lesion which may lead to dermal necrosis. Acute toxicity tests on guinea pigs have shown that exposures to propane at 43 000 ÷ 52 000 mg/m³ result in irregular breathing, which is the first symptom of propane poisoning, while the CNS depressing effect in exposed animals is observed at 90 000 mg/m³. No changes were noted in monkeys exposed for 90 days to propane at 1350 mg/m³.
No data could be located in the available literature concerning the carcinogenic activity of propane, and the results of the Ames test were negative.
Propane is absorbed primarily through the respiratory tract. Information on propane concentrations in human tissues comes from post-mortem examinations. Highest propane concentrations have been detected in adipose tissue, brain, liver, kidneys, lungs, and blood. Propane is removed from the system in exhaled air and urine.
Propane is a chemical causing asphyxia, because it expels oxygen from the air; it may also show a depressive Current admissible values of propane concentrations in the ambient air are based on the results of animal tests (propane shows a weak biological activity), while assuming that MAC (TWA) values for gases should not exceed 10% of the lower explosion level (LEL). In Germany and the USA, the admissible level for propane is 1800 mg/m³. Considering also the data quoted above, the authors of this report suggest for propane a MAC (TWA) value of 1800 mg/m³.
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Prop-2-yn-1-ol
Konrad Rydzyński
Prop-2-yn-1-ol (propargyl alcohol) is a light to straw-colored liquid with an odor like that of geraniums. Propargyl alcohol has been used to prevent hydrogen embrittlement of steel. It has also been used as a corrosion inhibitor, solvent stabilizer, soil fumigant, and chemical intermediate. Propargyl alcohol is highly toxic when ingested; it is an ocular and dermal irritant. Repeated inhalation of 183.2 mg/m³ (80 ppm) propargyl alcohol causes liver and kidney changes in rats. In a feeding subchronic study on rats the dose of 5 mg/kg was identified as the no-observed-adverse-effect level (NOAEL). The single percutaneous LD50 for propargyl alcohol in rabbits was 88 mg/kg. Based on animal data, the Expert Group for Chemical Agents has established an 8-hour MAC (TWA) value of 3 mg/m³. This value is intended to minimize the potential for reported eye and skin irritation and liver and kidney damage.
The MAC (STEL) value is not recommended at this time until additional toxicological data become available to provide a better base for quantifying on a toxicological basis what the MAC (STEL) should be.
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