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1,4-Phenylenediamine. Documentation
Krystyna Sitarek, Wojciech Wąsowicz
1,4-Phenylenediamine (PPD) occurs as crystals. It is a dye used for hair and fur, as an intermediate in manufacturing dyes and rubber accelerators. PPD is a toxic substance (LD50 per os for rats is 80 ÷ 90 mg/kg, CL50 for rats is 920 mg/m³). There are many reports of sensitivity to PPD in experimental animals and humans. 1,4-Phenylenediamine does not induce fetotoxic, teratogenic and carcinogenic effects.
Carcinogenic classification – IARC, group 3 – not classifiable as to carcinogenicity to humans; ACGIH – A4 – not classifiable as a human carcinogen.
ACGIH has recommended TWA of 0.1 mg/m3 for occupational exposure to 1,4-Phenylenediamine. The Expert Group for Chemical Agents has recommended TWA of 0.1 mg/m³ and notations “I” (irritant agent), Sk – skin and SEN – sensitization agent.
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Benzyl butyl phthalate. Documentation
Anna Pałaszewska-Tkacz, Sławomir Czerczak
Benzyl butyl phthalate (BBP) is a clear, oily liquid with a slight odour. It is used mostly as a plasticizer for polyvinyl chloride in vinyl floor tiles, vinyl foam and carpet backing. Furthermore, it is used in the production of sealants (polysulfide-, polyurethane-, or acrylic-based), adhesives (polyacrylic- and polyvinylacetate-based), paints (polyurethane- and polyacrylic-based), lacquers and inks (acrylic-, nitrocellulose- and vinyl resin-based).
As far as occupational exposure is concerned, the inhalation route of exposure is important, and to a lesser extent dermal contact. Because of low vapour pressure at room temperature, the high concentration of BBP can only occur during technological processes where the temperature is elevated or BBP aerosols are generated.
The reprotoxic activity of benzyl butyl phthalate has been confirmed, while in systemic toxicity studies increases in relative liver and kidney weights have been the most often observed effects. This effect was considered critical when the Polish OEL value of BBP was developed. It was agreed that the proposed value of 5 mg/m³ protected workers from the reproductive toxicity of BBP, too. It is also recommended to label BBP, in the Polish inventory of OELs, with the letters "Ft", a substance toxic to the foetus.
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Elemental iodine. Documentation
Jadwiga A. Szymańska, Elżbieta Bruchajzer
Elemental iodine (I2; CAS Register No. 7553-56-2) takes the form of greyish black to purple crystals. Aqueous solutions and vapours are brown or violet. Iodine sublimes to a violet gas with a character-istic, irritating odour.
Iodine is used in pharmaceuticals, lithography, photographic materials, and in manufacturing dyes. It is an ingredient in antiseptic preparations. Other uses include disinfectants that may be added to water. Occupational exposure to iodine may occur during the production and application of iodine compounds, and during other industrial activities.
This compounds is absorbed into the human body through the respiratory tract, skin (occupational exposure) and alimentary tract (general population, via iodised salt).
Ingestion of large quantities of iodine may cause burning of the mouth, throat, and stomach and abdominal pain, nausea, vomiting, and diarrhoea. Sufficient exposure may result in progression of symptoms to fever, shock, delirium, and death. Ingestion of 2-4 g has been fatal for humans. The solid element is intensely irritating to the eyes, skin, and mucous membranes. An allergic skin rash may occur.
Many years’ observations have shown that during occupational exposure to iodine vapours at the concentrations of up to 1 mg/m³ (0.1 ppm), there are no observed adverse effects. At the concentrations of 1.5-2 mg/m3 (0.15-0.2 ppm) work is possible, but difficult. Work is impossible at airborne iodine concentrations of 3-10 mg/m³ (0.3-1 ppm).
Iodine can be an intense irritant to the eyes, mucous membrane, and skin. It is a pulmonary irritant in animals.
Iodine absorbed by the lungs is changed to iodide and eliminated mainly in the urine. Organic iodine (approximately 95% of circulating iodine) exists as thyroxine (T4) and triiodothyronine (T3).
Iodine has a direct action on cells by precipitating proteins. The affected cells may be destroyed. In addition to the primary irritant action of iodine, this compound can act as a potent sensitizer.
The iodine concentration of 1 mg/m³ (occupational exposure of humans) was accepted as an NOAEL value and applying the correct uncertainly coefficient, the iodine MAC-TWA value was suggested to be 0.5 mg/m³ and, due to the compound irritating activity, a MAC-STEL value to be 1 mg/m3. Notation “I” – irritating substance is recommended.
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Mercury. Documentation
Andrzej Sapota, Małgorzata Skrzypińska-Gawrysiak
Mercury (Hg) is the only common metal which is liquid at conventional room temperature. It is found in nature mostly as cinnabar (mercuric sulfide, Hg5) and also as native mercury in the form of drops or silver crystalline amalgam.
In the mid 1970s world production of mercury was around 10 000 tonnes per year. By the end of the 1980s the use of mercury had rapidly decreased because of its adverse environmental effects. In recent years its annual world production has stabilized at the level of about 2500 tonnes.
Mercury is used in the production of alkaline batteries and fluorescent lamps, mercuric lamps in the chlor-alkali (electrolytic production of chloride and sodium hydroxide) and chemical (paint manufacturing, catalysts in chemical processes) industries. It is also used in control and measurement devices (thermometers, manometers, pressure valves), in dental preparations (amalgam) and in laboratories.
Mercury concentrations in chlor-alkali plants have recently ranged, depending on the country, from ‹ 10 to 430 µg/m3, and concentrations in the urine of the employees of those plants ranged from 0 to 750 µg/l.
In industrial plants, inhalation is the only way of workers’ exposure to Hg vapors. Inhalation exposure to other Hg inorganic compounds does not practically entail any risk.
In the cases of acute Hg intoxication, the lungs are the most critical organ. In occupational exposure the acute form of contamination with this metal is rather rare. Nevertheless, it has been found that high concentrations of Hg vapors induce various harmful effects on the nervous system, e.g., tremor, emotional liability, insomnia, memory disturbances, polyneuropathies, disturbances of cognitive and motor functions and vision disorders, whereas chronic exposure to mercury and its inorganic compounds exerts neurotoxic and nephrotoxic effects.
On the basis of the DL50 value for rats (25.7 mg/kg) and in accordance with the European Union (EU) classification, mercury and its inorganic compounds can be categorized as toxic compounds. On the basis of the available evidence, the International Agency for Research on Cancer categorized metallic mercury and its inorganic compounds as group 3, not classifiable as to its carcinogenity to humans.
Numerous reports have indicated mutagenic effects of mercuric chloride (II), but not of Hg vapors.
Although data on the effects of metallic mercury and its inorganic compounds on fertility in persons exposed to metallic mercury are contradictory, their adverse effects have been evidenced in animal studies. Bearing in mind that mercury penetrates the placental barrier it has been recommended to reduce exposure to mercury and its compounds to a minimum among women of child-bearing age.
Most data based on animal studies apply to inorganic mercury compounds, especially to mercuric chloride, whereas data obtained from epidemiological studies mostly apply to occupational exposure to Hg vapors.
Excessive occupational exposure to metallic mercury (vapors) and its compounds leads to psychiatric, behavioral and neurological symptoms and also to kidney damage. Thus, the neurological system and kidneys are major targets in chronic exposure to mercury and its inorganic compounds. Therefore, when setting MAC values, researchers should consider concentrations beyond which subclinical changes are not observed. Behavioral disturbances are the earliest consequences of exposure to Hg vapors, therefore the proposed MAC value should be set for Hg vapors and the obtained standard value should protect workers against harmful effects of both vapors of mercury and its inorganic compounds.
The results of epidemiological studies on early mercury-induced neurotoxic effects have been taken as the basis for setting MAC values for Hg vapors and inorganic compounds. Most of those results showed that the health condition of the persons under study were more correlated with the results of biologic monitoring (urine and blood Hg concentrations) than with those of air monitoring. That is why the proposed hygiene standards have been deduced from Hg concentrations in urine.
Most authors of epidemiological studies adopt the value of 35 µg/g creatinine in urine as the threshold concentration; at higher concentrations adverse effects on the peripheral nervous system and on the kidneys have been observed. Meta analyses of epidemiological studies reveal potential toxic effects of mercury on human behavior already after exposure to urinal Hg concentration within the range of 20 ÷ 30 µg/g creatinine.
In our opinion, on the basis of the arguments used to justify the adoption of EU standards and the results of meta analyses, the level of 30 µg Hg/g creatinine in urine should be set as the level protecting against the development of behavioral disturbances. This value is proposed to be adopted as a biological limit value (BLV).
Extrapolation from biological monitoring values to airborne exposure to mercury show that Hg concentration in the air at the level of 0.02 mg/m³ would correspond with the recommended Hg concentration in urine (30 µg/g creatinine). We propose to adopt this level as the MAC value. The proposed standard values (MAC, 0.020 mg/m³ and BLV 30 µg/g creatinine) are in agreement with norms adopted by the European Union.
The proposed hygienic standards should protect workers against adverse effects of both mercury vapors and inorganic compounds. Setting the STEL concentration of mercury and its compounds is not warranted.
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