Chromosome changes with time in lymphocytes after occupational exposure to toluene.

Chromosome analyses were carried out in peripheral lymphocytes of 27 workers exposed to toluene in a rotogravure plant. At the time of blood sampling all of them had not been exposed to toluene for at least 4 months up to 5 years. Up to 2 years after cessation of exposure to toluene a higher incidence of chromatid-type aberrations could be observed than in controls. After longer post-exposure periods the aberration yields can no longer be distinguished from background level. No differences were revealed in SCE frequencies of smoking or non-smoking workers post toluene exposure compared with the corresponding controls.