|
|
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
|
|
 |
Benzene. Documentation of maximum admissible values for occupational exposure
Grażyna Lebrecht, Sławomir Czerczak, Wiesław Szymczak
Benzene is a clear, flammable, liquid with a characteristic odor. Leukaemia is the main effect at long-term occupational exposure to benzene. The unit risk of leukaemia, i.e. the lifetime risk attributable to the inhalation exposure to 1.6 mg/m³ benzene was assessed by many authors from the results of epidemiological studies on subjects occupationally exposed to benzene. The results of those assessments ranged from 6,6 · 10-4 to 1,4 · 10-3, acceptable for occupational exposure.
Based on these epidemiological data the Expert Group for Chemical Agents establishment an 8-hour MAC (TWA) value of 1,6 mg/³. There are no bases for establishing benzene MAC (STEL). The Expert Group also recommended BAIs for benzene: S-Phenylomercapturic acid in urine 25 µg/g creatinine and trans, trans muconic acid in urine 500 µg/g creatinine.
|
N,N-Dimetyloformamide. Documentation of maximum admissible values for occupational exposure
Andrzej Sapota, Danuta Ligocka
Domethyloformamide (DMF) is a colourless and hygroscopic liquid with a faint odour of amines. It is mainly used as a liquid and gas solvent in organic synthesis in the process of producing low – and high-molecular vinyl and acryl polymers, foil, fibres and coatings.
IN 1995, the world productions of DMF was about 500,000 tons. In the USA, where in 1987 DMF productions exceeded 250,000 tons, about 120,000 people were exposed to this compound. In Poland the exact number of people exposed to DMF is unknown. In 1995, in one of the plants producing artificial leather, about 300 workers were occupationally exposed to this compound. 50 of them were exposed to concentrations exceeding the so far obligatory TLV value (10 mg/m³).
Accordings to European Union instructions No. 92/32/EEC DMF should be included in the group of harmful compounds. On the basis of the results of investigations on laboratory animals the compound does not demonstrate irritating, sensitizing, carcinogenic or teratogenic effect. In numerous in vitro and in vivo tests the compound showed no genotoxic effect. In high doses DMF reveals hepatotoxic effect observed in many animal species after administration of the compound in various ways and at different times. Intensification of DMF hepatoxic effect was found depending on the applied doses. DMF is absorbed in the form of vapours in the airways and through skin. In experimental studies on volunteers, DMF retention in lungs was about 90%. Liquid DMF applied on skin is absorbed very quickly and the determined In humans absorption coefficient is 9 mg/cm²/h. Systematic activity on liver has been assumed to be critical effect of the compound. To calculate and establish a TLV value the NOEL value of 75 mg/m³ for rats in the condition of 2-year inhallatory exposure was accepted. Taking into consideration the above data, the so far used value 10 mg/m³ has been suggested to be retained as a TLV value for DMF. The calculated TLV value of the compound should prevent health effects of long-term exposure to DMF is occupational exposure. Moreover, we suggest accepting a BEI value, like in Germany and the USA, where determination of N-methylformamide (one of main DMF metabolites) in urine is required. In Germany, the obligatory TLV value for DMF is 30 mg/m³ and the BEI value is 15 mg N-methylformamide/l of urine. Due to rectilinear dependence of N-methylformamide urine concentration on DMF concentration in the air after adequate calculation for the suggested by us TLV value (10 mg/m³), the BEI value in Poland should be 5 mg NMF/l of urine. Considering high DMF skin absorption in the liquid and vapour form we suggest and additional determination with letters Sk. There are no bases for establishing a STEL value.
|
Phenol. Documentation of maximum admissible values for occupational exposure
Marek Jakubowski
Phenol is a white crystalline solid. Its major use is a feedstock for phenolic resins, caporolactam, xylenoles aniline. Some medical and pharmaceutical applications are also known. Occupational exposure to phenol may occur during the production of phenol and its products, during the application of phenolic resins in wood and iron/steel industries and during other industrial activities.
Phenol is readily absorbed by all routes of exposure. The retention of phenol vapors in lungs amounts to about 60 – 80%. The rate of penetration of phenol through skin is from 0,08 to 03 mg/cm²/h. Absorbed phenol mainly conjugates with glucuronic and sulfuric acid and, to a lesser extent, hydroxylates into catechol and hydroquinone. Half-time of excretion of phenol in urine after inhalation exposure amounts to 3,5 h.
A wide range of acute effects has been reported following human exposure to phenol by dermal, oral or intravenous routes. Adequate human data on the effects of chronic inhalation exposure are not available.
In rats, mice and monkeys exposed continuously to phenol for 90 days, an inhalation NOAEL of 19 mg/cm³ was reported, based on kidney, liver, brain and hearth effects. In a 14-day study in rats, an oral NOAEL of 12 mg/kg/day was reported, based and kidney effects. At 40 mg/kg/day, the pathological changes in the kidneys included two animals with tubular degeneration in the papillar region, and one with protein casts in the tubules. According to the U.S. EPA the NOAEL for productive effects amounts to 60 mg/kg/day.
Solutions of phenol are corrosive to skin and eyes. Phenol vapors can irritate the respiratory tract. RD50 of 624 mg/m³ has been reported in mice.
The evidence for the carcinogenicity of phenol in laboratory animals was considered by the IARC to be inadequate.
Time weighted average occupational exposure limits in different countries is from 4 to 19 mg/m³. Based on NOAEL value from inhalation study in rats the TWA value of 7,8 mg/m³ was proposed. No STEL value has been proposed. Substance is corrosive and can be absorbed through skin.
|
Methylamine. Documentation of maximum admissible values for occupational exposure
Sławomir Czerczak, Małgorzata Kupczewska-Dobecka
Methylamine is a gas at ambient temperature and pressure which has a pungent, fishy, ammoniacal odor and saline taste. Methylamine is available either as an anhydrous compressed gas or as a 30%, 40% and 50% aqueous solution. Methylamine has been used as an insect attractant, as a warning agent in natural gas, as a flotation agent, and as an intermediate in chemical synthesis.
Methylamine is corrosive to human skin and eyes. A concentrated aqueous solution applied to intact human skin caused severe burning and hyperemia. The nasal, eye and skin irritation occured as a consequence of chronic exposure to a methylamine vapors at concentration of 32 mg/m³, but that exposure at concentrations of 12,8 mg/m³ produced no observable irritation.
The RD50 concentration (the concentration which produces a 50% reduction in breath rate in exposed mice) was 180 mg/m³.
Based on the human data the Experts Group of Chemical Agent established the 8-hour TWA value of 5 mg/m3, and the STEL value of 15 mg/m³.
|
Hydrogen selenide. Documentation of maximum admissible values for occupational exposure
Małgorzata Kupczewska-Dobecka, Sławomir Czerczak
Hydrogen selenide is a non-metallic compound currently receiving attention in both medicine and electronics. Hydrogen selenide is extremely flammable. Toxicity results in multiple symptoms, the most characteristic of which is a garlicky odor of the breath.
A single inhalation concentration LC50 of hydrogen selenide is reported to be between 1 and 12,7 mg/m³ for 1- and 8-hour exposure. A young woman exposed repeatedly to hydrogen selenide gas developed gastrointestinal complaints, dental caries, conjuctivitis, nail deformities, and garlicky breath. Five cases of subacute intoxication from less than 0,67 mg/m³ of hydrogen selenide probably generated from the use of selenious acid have been reported. Gastrointestinal distress, dizziness, increased fatigue, moderate eye and nasal irritation and a metallic taste in the mouth were reported.
The LOAEL (lowest observed adverse effect level) of 0,67 mg/m³ was adopted. Given these data, the 8-hour TWA value is 0,05 mg/m³, and the STEL value is 0,1 mg/m³.
|
Sulfotep. Documentation of maximum admissible values for occupational exposure
Renata Soćko, Sławomir Czerczak
Sulfotep is a pale yellow, noncombustible liquid with a garlic odor. It is often used in greenhouse fumigant formulations for control of aphids, spider mites, whiteflies, and thrips.
Sulfotep is an organophosphate pesticide whose toxicity is similar to that of paration. Poison by ingestion, skin contact and possibly other routes. Sulfotep is an organophosphate cholinesterase inhibitor; inhibited cholinesterase activity in the plasma, erythrocytes and in brein. Sulfotep is highly toxic following oral administration and following dermal application. The dermal LD50 for rats is 65 mg/kg, and the oral LD50 for the rat is 5 mg/kg and 13,8 mg/kg.
Based on the fact that inhalation of an aerosol concentration of 1,94 mg/m³ of sulfotep administered to rats 6 hours/day, 5 days/week for 12 weeks failed to produce any adverse effects, a concentration 0,1 mg of sulfotep/m³ is proposed as a maximum exposure limit (maximum allowable concentration). Because sulfotep has been shown to penetrate the skin in amounts sufficient to induce systemic toxicity, the skin notation is considered appropriate. At this time, no STEL is recommended until additional toxicological data.
|
Triethylamine. Documentation of maximum admissible values for occupational exposure
Andrzej Sapota, Małgorzata Skrzypińska-Gawrysiak
Triethylamine (TEA) is a strong basic liquid used mainly as a catalyst in the polymerization process and as an emulsifying agent for dyes and pesticides. TEA vapours in high concentrations have an irritating effect on eye mucosa and upper airways. In the form of a solution the compound strongly irritates eyes and, moderately, rabbit skin. In semi-long term investigations, 6-week exposure of rabbits to TEA of 210-414 mg/m³ concentrations results in degenerative changes in the liver, kidneys, myocardium and cornea erosions. No mutagenic activity of the compound is observed in Ames’s test and sister chromatids exchange test. There is no data on TEA carcinogenic activity in animals and humans. The compound is well absorbed in the form of vapours in the airways and through skin as a solution. On the basis of epidemiologic studies on subjects occupationally exposed to TEA reversible, temporary blurring of vision manifesting itself by deterioration of visual activity, perception of contrast sensitivity and increase of corneal thickness, corneal oedema as well as formation of subepithelial microcysts were revealed. Blurred vision is a typical symptom of triethylamine effect on humans.
In studies concerning the assessment of industrial exposure to TEA, subjective and objective symptoms of blurred vision observed when mean TEA concentration in the air exceeded 10 mg/m³. On a work-stand, where mean concentrations were 4 and 5 mg/m³ blurred vision was not recorded.
A TLV was esrablished on the basis of an experimental evaluation of blurred vision after inhalatory exposure to TEA of 4 volunteers perfomed by Jarvinen et al., in 1999. Four-hour exposure to TEA of 40,6 mg/m³ concentration resulted in all investigated subjects in subjective blurred vision, objective deterioration of visual activity and contrast perception, cornea thickening, significant corneal oedema as well as formation of subepithelial microcysts. After exposure to TEA of 6,5 mg/m³ concentration, subjective blurred vision was observed only in 2 subjects, whereas changes in cornea were insignificant. TEA concentration of 3 mg/m³ did not cause any changes in cornea or subjective blurred vision. We suggest accepting a TLV for triethylamine on the level of 3 mg/m³ as mean concentration weighted with 8 h worktime. Due to the irritating action we suggest a concentration of 9 mg/m³ as a STEL value. We also suggest accepting a BEI value on the level of 28 mmol of TEA unchanged in urine collected before work completion in conversion to 1 mol of creatinine (25 mg TEA/g creatinine).
Taking into consideration the fact that TEA in rabbits is very well absorbed through skin, the compound should be described with letters Sk.
|
|
|
