Long-term effects of feeding aflatoxin-contaminated market peanut oil to Sprague-Dawley rats

Peanut oils obtained from Hong Kong markets were frequently contaminated with aflatoxins. A ‘purified’ diet in which aflatoxin-contaminated market peanut oil (aflatoxin B₁ 110 ppb [μg/kg]) was used as the fat source was fed to Sprague-Dawley rats for 22 months from weaning. Its estimated aflatoxin B₁ content was 5–7 ppb. Controls were fed a diet of identical composition except that Mazola corn oil (aflatoxin-free) was used. At autopsy, three out of 76 aflatoxin-fed rats were found to have sarcomas—one in the liver, one in the wall of the colon and one in the subcutaneous tissue of the groin. Eighteen animals fed peanut oil showed parenchymal liver damage and varying degrees of fatty change and one showed pre-malignant changes in liver cells. Of 90 control rats, none developed malignant tumours. The liver-to-body weight ratios for experimental and control rats were 2·93 ± 0·46 and 2·62 ± 0·58, respectively (means ± 1 SD). The difference between these values was statistically significant (P < 0·01), reflecting the degree of fatty change in the livers of experimental rats compared with that in the controls. Over 90% of Hong Kong households use peanut oils for cooking purposes, and these data appear to indicate a possible health hazard in the use of peanut oils contaminated at the levels found.