o-TOLUIDINE CAS N°: 95-53-4 - UNEP Chemicals

OECD SIDS o-TOLUIDINE
depending on the work to be done (e.g. full protective clothing and gas filter masks (classification
ABEK) (Bayer Chemicals, 2004).
Down stream users of o-toluidine are informed by way of a material safety data sheet on the
recommended safety measures (see above) (Bayer Chemicals, 2004).
Potential exposure at the workplace
In Germany for occupational settings, a Technical Exposure Limit (TRK) of 0.5 mg/m³ is set for
o-toluidine. At Bayer Chemicals production and processing sites, the exposure of workers is well
below this limit (Bayer Chemicals, 2004). Investigations of the workplaces have been performed
also according to German Technical Guidance TRGS 402 (AGS, 1997).
In the USA, 13,053 workers were estimated to be potentially exposed to o-toluidine in the workplace
in 1972 - 1974. In a similar survey, approximately 30 000 workers, including approximately
15 500 women, were estimated to be occupationally exposed to o-toluidine in 1981 - 1983.
Occupations with the greatest potential for exposure to the compounds include dye and pigment
makers (several sources, cited according to NTP, 2003). In the Finnish Register of Employees
Exposed to Carcinogens, 90 laboratory workers, health care workers and university teachers were
listed as exposed to o-Toluidine or its salts (IARC, 2000). In a study on “most commonly used
carcinogenic” laboratory chemicals, Wennborg et al. (2001) report that 9 (out of at least 113) and 11
(out of at least 144) biomedical research groups used o-toluidine in 1970 - 1974 and 1975 - 1979,
respectively, in Sweden. For the 1980s, o-toluidine is not mentioned as being one of the “most
commonly used carcinogenic” laboratory chemicals (Wennborg et al. 2001), indicating that uses of
analytical chemicals change due to development of new methods.
Although very high levels of other compounds occured (e.g. > 300 mg/m 3 of acetanilide), the level
of o-toluidine was reported to be less than 0.5 ppm (2.9 mg/m 3 ) in a dye manufacturing plant in the
USA during the mid-1940s (Ott and Langner, 1983). The extremely high levels of o-toluidine in
urine of workers from this plant (see below) shed some doubt on the reliability of these exposure
data.
In the early 1980s concentrations in the air at a facility producing dyes and pigments ranged from
0.004 to 0.26 ppm (0.02 - 1.5 mg/m 3 ). In area samples taken in the air at two coal liquification pilot
facilities, the mean concentration of o-toluidine was < 0.1 ppm (< 0.6 mg/m 3 ). Medical and
laboratory personnel represent a significant population of workers potentially exposed to
o-toluidine. Laboratory air concentrations were determined to be below 22 mg/m 3 before 1984
(NTP, 2003). In a chemical plant of the former USSR, although the maximum permissible level for
o-toluidine was 3 mg/m 3 , workers were generally exposed to o-toluidine concentrations of 6 -
20 mg/m 3 , with the highest levels up to 29 mg/m 3 . During shift, there was a dermal deposition of
0.01 - 0.03 mg/100 cm 2 of skin, and patches of cloth collected 0.1 mg/100 cm 2 of textile
(Khlebnikova et al., 1970, cited according to IARC, 2000).
In an antioxidant manufacturing plant in the USA, working place air of exposed workers contained
o-toluidine (average 0.4 mg/m 3 ) and other amines, e.g. aniline (Ward et al., 1996).
Biological monitoring
There are several published reports on the biomonitoring of workers involved in the manufacturing
and processing of o-toluidine.
In 1948, urine of workers of dye manufacturing plant in the USA, contained o-toluidine at
concentrations of < 0.3 - 1.7 mg/l. The exposure level of o-toluidine was reported to be less than
0.5 ppm (2.9 mg/m 3 ) (Ott and Langner, 1983).
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