95-53-4 Intermediate Organic Chemistry Azo Dyes 2-Methylaniline

Azo Dyes Fine Chemical Intermediates Named O-Toluidine

O-Toluidine is used as an intermediate in the synthesis of the large-volume metolachlor and acetochlor, herbicides, in the manufacture of more than 90 dyes and pigments (e.g. azo pigment dyes, acid-fast dyestuffs, triarylmethane dyes, indigo compounds and sulfur dyes), and as an intermediate for synthetic rubber and rubber-vulcanizing chemicals, pharmaceuticals, pesticides, and other chemicals. O-Toluidine is also used in the clinical laboratory as an ingredient in a reagent for glucose analysis, and for tissue staining.

Acute human exposure to o-Toluidine can cause painful hematuria (presence of red blood cells in the urine) (Goldbarb and Finelli, 1974). Chronic exposure to o-Toluidine in humans was also observed in multiple retrospective cohort studies in the dyestuff industry. The results include increased incidence of death and increased incidence of bladder cancer. It proved difficult however to definitively link these to o-Toluidine in due to the exposure to other expected carcinogenic compounds in the dyestuff industry. One study assessed the increased incidences of mortality and bladder cancer in 906 employers of a dyestuff factory in northern Italy over a mean latent period of 25 years. Mortality from bladder cancer was significantly higher in the employers than the people only exposed to the particular chemicals present in the factory, in use or intermittent contact. o-Toluidine was concluded to be almost certainly capable of causing bladder cancer in men.

Another study recorder expected and observed cases of bladder cancer at a rubber factory in upstate New York (Ward et al., 1991). The study assessed 1,749 male and female employees over a period of 15 years. Exposure was primarily to o-Toluidine and aniline and a significant increase in incidences of bladder cancer was observed. However, the carcinogenicity could not be attributed to o-Toluidine definitively. Other studies include Vigliani & Barsotti (1961), Khlebnikova et al. (1970), Zavon et al. (1973), Conso & Pontal (1982), and Rubino et al. (1982).