Comparison of the effects of 13 phenolic compounds in induction of proliferative lesions of the forestomach and increase in the labelling indices of the glandular stomach and urinary bladder epithelium of Syrian golden hamsters

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Abstract
Groups of 6-week-old male Syrian golden hamsters were given 13 different phenolic compounds for 20 weeks. Of these compounds, 2(3)-te/f-butyl-4-methoxyphenol (BHA), 2-tert-butyl-4-methylphenol (TBMP) and p-tert-butylphenol (PTBP) strongly induced hyperplasia and tumorous lesions in the fore-stomach. Catechol, p-methylphenol (PMYP), P-methoxy-phenol (PMOP), caffeic acid, methylhydroquinone (MHQ) and pyrogallol were less active, and resorcinol, hydroquinone, propylparabene and terf-butylhydroquinone (TBHQ) were not active. The labelling index in the forestomach epithelium was significantly increased by addition to the diet of BHA, TBMP, catechol, PMOP, PTBP and MHQ. PMOP induced epithelial damage and regenerative hyperplasia of the pyloric region. Catechol, caffeic acid and PMYP induced similar though less marked lesions. The labelling index in the glandular stomach was significantly increased by oral catechol (P < 0.05) or PMOP (< < 0.05). No histopathologkal lesions were observed in the urinary bladder epithelium, but propylparabene (P < 0.05), catechol, TBHQ and MHQ increased the labeling index. These findings indicate that PTBP and TBMP may be carcinogenic for hamster forestomach after long-term administration, and that both one hydroxy and tert-butyl substi-tuents may be important for induction of hamster forestomach tumors.