Amonia. Documentation of maximum admissible values for occupational  exposure Maciej Tarkowski, Stanisław Tarkowski Cyanamide. Documentation of maximum admissible values for occupational exposure Małgorzata Kupczewska-Dobecka, Sławomir Czerczak Hydrogen cyanide and cyanide salts – sodium, potassium and calcium. Documentation of maximum  admissible values for occupational exposure Jolanta Skowroń 1,1-Dichloroethane. Documentation of maximum admissible values for occupational exposure Marek Jakubowski 1,2-Dichloroethane. Documentation of maximum admissible values for occupational exposure Marek Jakubowski 2,2’-Dichloro-4,4’-methylenedianiline. Documentation of maximum admissible values for occupational exposure Krystyna Sitarek, Grażyna Lebrecht 1,1-Dimethylhydrazine. Documentation of maximum admissible values for occupational  exposure Andrzej Starek Dimethyl ether. Documentation of maximum admissible values for occupational exposure Andrzej Starek 4-Hydroxy-4-methyl-2-pentanone. Documentation of maximum admissible values for occupational exposure Jerzy Piotrowski,  Elżbieta Bruchajzer Contents of. Nos. 2(32)2002 – 1(35)2003

Amonia. Documentation of maximum admissible values for occupational exposure
Maciej Tarkowski, Stanisław Tarkowski

Amonia is a colourless gas of an unbearable odour, detectable in air concentrations from 0.6 to 40 mg/m³. Ninety percent of amonia is in water in the form of amonia ions.
Over 90% of amonia in the atmospheric air is of natural origin and only 5% originates from industrial production. Eighty percent of the latter is utilised in the production of fertilisers.
The main source of exposure is amonia in the air. Exposure through ingestion or through skin penetration can only take place in the case of accidental ingestion of amonia or as a result of splashing a highly concentrated solution.
The effects of repeated exposure to amonia are mainly in the form of irritation of the upper respiratory tract. Amonia is rapidly absorbed in the upper respiratory tract and removed from the body through exhalation.
There is no literature data indicating teratogenic, genotoxic or carcinogenic effects.
The lowest observed concentration which caused irritation of the upper respiratory tract (LOAEL) was 70 mg/m³.
The air concentration of amonia of 35 mg/m³ was used as the highest permissible concentration, at which no adverse health effects could be observed (NOAEL). Taking into account individual sensitivity among people and the standard value established in the European Union, it has been proposed that the highest permissible concentration of amonia should be 14 mg/m³ as an average during an 8-hour work shift, and 28 mg/³ as a short-term exposure limit in view of its irritation effect.

Cyanamide. Documentation of maximum admissible values for occupational exposure
Małgorzata Kupczewska-Dobecka, Sławomir Czerczak

Cyanamide is a combustible, deiquescent, crystalline solid. However, it is usually found as a 25% liquid solution. Cyanamide is used as a chemical intermediate for dicyandiamide in manufacturing melamine and carbendazime. It is also used in fumigants, metal cleaners, refining of ores, production of synthetic rubber, and in chemical synthesis.
Cyanamide is moderately toxic in rats, as determined by oral ingestion. The LD₅₀ is 125 mg/kg. It is very irritating and caustic to the skin. Cyanamide was severely irritating when instilled into a rabbit’s eye. The „antabuse” effect of cyanamide was about half as severe as that of antabuse and only one-sixth that of thiram.
The NOAEL (no observed adverse effect level) of 7 mg/kg was adopted.
On the basis of the NOAEL value and human data the Expert Group of Chemical Agents established an 8-hour TWA value of 2 mg/mm³ and a STEL value of 4 mg/m³.

Hydrogen cyanide and cyanide salts – sodium, potassium and calcium. Documentation of maximum admissible values for occupational exposure
Jolanta Skowroń

Hydrogen cyanide (HCN) is a colourless gas at room temperature. It has a bluish-white cast when liquefied. Both forms has a characteristic faint odour resembling bitter almonds for those individuals able to perceive its presence by smell. The alkali cyanides, sodium cyanide [NaCN], potassium cyanide [KCN], and calcium cyanide [Ca(CN)₂] are white, deliquescent, noncombustible solids which have a faint odour of bitter almonds.
HCN is encountered during its manufacture as a reagent; in the production of chemical intermediates for the manufacturing of synthetic fibres, plastics, cyanide salts, and nitrites; in the fumigation of ships, railroad cars, buildings, orchards, tobacco, and various foods; and it can be produced during petroleum refining, electroplating, metallurgy, and photographic development. NaCN and KCN are used in the extraction of gold and silver from ores; electroplating; metal cleaning; heat treatment of metals; as insecticides and fumigants; and as raw materials in the manufacture of dyes, pigments, nylon, and chelating agents. Ca(CN)₂, the other cyanide of major commercial importance, is used chiefly as a fumigant because it readily releases HCN when exposed to air.
The primary route of entry of hydrogen cyanide and its salt in the workplace is by inhalation, and absorption through the skin. In addition, NaCN, KCN, and Ca(CN)₂ will liberate HCN gas upon hydrolysis or in the presence of acids.
Many reports of acute toxicity resulting from accidental exposure to HCN have appeared in the literature. The symptoms of accidental exposure of humans to HCN were lightheadedness, breathlessness, feeling shaky, headache, and nausea. Inorganic cyanides are also reported to be rapid-acting acute poisons to humans.
The symptoms of chronic exposure of workers were headache, changes of taste and smell, irritation of throat, vomiting, dyspnoea, nervous instability and enlargement of the thyroid.
The acute LD₅₀ values of HCN, NaCN, Ca(CN)₂ and KCN for laboratory animals classify the compounds as very toxic.
HCN and cyanide salts act by the same mechanism, namely the release of cyanide ion. Enlargement of the thyroid gland was attributed possibly to the effects of thiocyanate, the chief metabolite of cyanide.
The MAC-Ceiling for HCN and it salts (sodium, potassium, calcium), as CN 5 mg/m³, is recommended to provide a greater margin of safety against acute poisoning and to minimize the risk to exposed workers of throat irritation, headache, and symptoms resulting from chronic exposure to cyanide such as thyroid enlargement. Because HCN and its salt can be rapidly absorbed through the skin in lethal amounts, the skin notation (Sk) is retained.

1,1-Dichloroethane. Documentation of maximum admissible values for occupational exposure
Marek Jakubowski

1,1-Dichlorethane is a colorless and flammable liquid, with an odor similar to chloroform. It has been used as an intermediate in manufacturing vinyl chloride and 1,1,1-trichloroethan.
It is used as a solvent for oils and fats and as a degreaser.
1,1-dichloroethane has low acute and chronic toxicity. The oral LD₅₀ in rats is, according to different sources, from 0,725 to 14,1 g/kg. TLC0 is 24 g/m³ and LC₅₀ 52 g/m³.
The CNS, liver and kidney are target organs for 1,1-dichloroethane, with cats appearing as the most sensitive species. The lowest NOEL that has been established in a 13-week inhalation study is 2025 mg/m³. The evidence of carcinogenicity is inconclusive for 1,1-dichloroethane. According to ACGIH 1,1-dichloroethane belongs to group A4 and according to US EPA to group C.
Limited data are available to estimate the toxicity of 1,1-trichloroethane for humans. It is reported to irritate eyes and the respiratory tract, producing salivation, sneezing and coughing.
Based on the data from the animal studies with repeated inhalations, a MAK (TWA) value of 400 mg/m³ is recommended. At this time no MAK (STEL) is recommended.

1,2-Dichloroethane. Documentation of maximum admissible values for occupational exposure
Marek Jakubowski

1,2-Dichloroethane is a colorless, flammable liquid with an odor typical of chlorinated hydrocarbons. It has been used as an intermediate in the manufacture of vinyl chloride; as a degreaser, fumigant, and solvent.
In humans a number of deaths from accidental ingestion of 1,2-dichloroethane ant three fatal cases from inhalation have been reported. Liver and kidney injury was found in all cases. Several episodes of occupational intoxication have been reported with nausea and vomiting as predominant symptoms.
The oral LD₅₀ in rats is 680 mg/kg and in mice 489 mg/kg in males and 413 mg/kg in females. The LC₅₀ in rats is 48000 mg/m³ after 32-min exposure and 4000 mg/m³ after 432-min exposure.
Animal studies have uniformly indicated liver and kidney injury from exposure to 1,2-di-chloroethane. The lowest NOEL that has been established in a 2-year inhalation study of rats (50 males and 50 females) is 200 mg/m³. Studies on animals have shown that 1,2-dichloro-ethane is well absorbed through the skin following dermal exposure (2,8 mg/cm²/h).
The International Agency for Research on Cancer classified 1,2-dichloroethane in group 2B. However, sufficient evidence of carcinogenicity in rats and mice was derived from studies employing gavage as the route of administration and as a result concentrations of 1,2-dichlo-roetane in the body directly after absorption were very high. According to ACGIH this limited evidence of carcinogenicity is of questionable relevance to industrial exposure.
Based on the results of chronic animal inhalation studies cited above MAK (TWA) of 50 mg/m³ for 1,2-dichloroethan is recommended. Skin notation is recommended. Sufficient data were not available to recommend a TLV (STEL).

2,2’-Dichloro-4,4’-methylenedianiline. Documentation of maximum admissible values for occupational exposure
Krystyna Sitarek, Grażyna Lebrecht

2,2’-Dichloro-4,4’-methylenedianiline (MOCA) is a commercially important aromatic amine used as a curing agent in the production polymers. The chemical is moderately toxic, an oral LD₅₀ in rats is 750 ÷ 1140 mg/kg b.w., and in mice 640 ÷ 880 mg/kg. MOCA is irritating to the skin and eyes. This chemical is extensively metabolized in rats. MOCA is known mutagenic and carcinogenic in rats, dogs and mice. In female mice but not in males, a statistically significant incidence of hepatoma was observed when the animals given MOCA in diet. A higher incidence of tumors was observed in treated animals than in control as follows: hepatomas and lung adenomatosis in rats, hemangiosarcomas and hemangiomas in mice.
The Expert Group of Chemical Agents recommends a MAC (TWA) of 0,02 mg/m³ for 2,2’-dichloro-4,4’methylenedianiline. Considering the fact that the absorption by skin is significant we suggest to determine the substance with the symbol “Sk” and R 2 – the agent is probably carcinogenic to humans.

1,1-Dimethylhydrazine. Documentation of maximum admissible values for occupational exposure
Andrzej Starek

1,1-Dimethylhydrazine (UDMH) is a colourless liquid with an ammonia odour. This compound is used as a component of racket fuels, absorbent of acidic gases, reducer, and intermediate in organic synthesis.
The acute toxicity of UDMH in animals qualifies this compound as a harmful substance. During repeated exposure UDMH exerted diuretic, immunosuppressive, hemolytic, depressive or exiciting, hepatotoxic, nephrotoxic, and carcinogenic effects. Moreover, its genotoxic and mutagenic effects have been confirmed.
The MAC value of 0,1 mg/m³ was estimated on the basis of the LOAEL value (12 mg/m³) obtained in experiments on dogs (24 weeks) and relevant uncertainty factors. Skin (Sk) notation is recommended.

Dimethyl ether. Documentation of maximum admissible values for occupational exposure
Andrzej Starek

Dimethyl ether (DME) is a colourless gas used mainly as a dispersant, refrigerant, racket fuel, and starter in a petrol engine.
DME is relatively low toxic in laboratory animals during a single exposure. The central nervous system, hematopoietic system, and liver are major targets in DME subchronic and chronic toxicity. This compaund does not cause genotoxic, carcinogenic, embriotoxic, and teratogenic effects.
The proposed maximum exposure limit (MAC) of 1000 mg/m³ is based on the LOAEL value (19100 mg/m³) derived from long-term (104 weeks) studies on rats and relevant uncertainty factors.

4-Hydroxy-4-methyl-2-pentanone. Documentation of maximum admissible values for occupational exposure
Jerzy Piotrowski, Elżbieta Bruchajzer

4-Hydroxy-4-methyl-2-pentanone (diacetone alcohol, DAA) is a colourless, flammable liquid with a slight scent. Exposure to DAA can take place during its production and use.
Acute intoxication in humans has not been reported. DAA can have an irritating effect. Longterm exposure can evoke damage of the liver and kidneys. Medial lethal doses of DAA after intragastric administration were found in various animal species within the limits of 3950 ÷ 4700 mg/kg suggesting low toxicity. A single exposure by inhalation in concentrations of 7125 to 9975 mg/m³ caused anxiety, irritation, catarrh, incitement, and sleepiness. Following exposure by inhalation for 6 weeks the value of NOAEL was set at 232 mg/m³. LOAEL was established at 1035 mg/m³, on the basis of a slight increase in the weight of the liver. Maximum effects exemplified by transient sleepiness, a slight decrease in body weight and a slight increase in the weight of the liver and kidneys were found following exposure to DAA of 4494 mg/m³.
DAA did not show mutagenic or clastogenic effects, or cancerogenic, embriotoxic, and teratogenic effects.
Ethyl alcohol intensified the depressive action on the central nervous system. This interaction also prolonged the action of ethanol.
The Threshold Limit Value (TLV) for DAA accepted by ACGIH was based on experiments on volunteers exposed to a range of DAA concentrations in the air. Following a 15-minute exposure to DAA in a concentration of 475 mg/mm³ (100 ppm) the scent of DAA became unpleasant, and this concentration was accepted as LOAEL for the irritating effect. The value of TLV is proposed accepting the uncertainly factor of 2. A MAC equal to 240 mg/m³ was also accepted in other countries. In concentrations lower than 240 mg/m³ no toxic effects were apparent in workers of in the American industry.