Chronic toxicity of three food colourings: Guinea Green B, Light Green SF Yellowish and Fast Green FCF in rats, dogs and mice

Abstract

The results of feeding rats, dogs and mice diets containing Guinea Green B, Light Green SF Yellowish or Fast Green FCF for 2 yr are reported. Results of weekly subcutaneous injections of each of the three colourings into rats for 2 yr, as well as thrice-weekly intraperitoneal injections of Light Green SF Yellowish for 2 yr, are also reported. Guinea Green B, Light Green SF Yellowish or Fast Green FCF were fed to groups of weanling Osborne-Mendel rats, 50 per group and evenly divided by sex, at dietary levels of 0·0, 0·5, 1·0, 2·0 and 5·0% for 2 yr. Growth inhibition occurred in male rats fed Light Green SF Yellowish at the 2 and 5% levels and in females at the 5% level. No gross or microscopic lesions could be attributed to the feeding of Light Green SF Yellowish or Fast Green FCF. Rats fed Guinea Green B at the 5% level were mildly anaemic. Growth depression was observed in male animals on both the 2·0 and 5·0% feeding levels. Liver weights, expressed as organ to body weight ratios, were increased in males at the 2 and 5% levels and in females on the 5% level. Pathological effects attributable to ingestion of the colouring were limited to hepatic changes, the most important being increased incidence of total hepatic neoplasms (nine rats on 5% versus none in controls; however, only two were malignant). Intraperitoneal injections of Light Green SF Yellowish for 2 yr in rats did not produce any tumours. A high incidence of injection-site fibrosarcomas was produced in rats given repeated subcutaneous injection of Light Green SF Yellowish or Fast Green FCF. A lesser incidence was obtained with Guinea Green B. The three green colourings, Guinea Green B, Light Green SF Yellowish and Fast Green FCF, were each fed at dietary levels of 0·0, 1·0 and 2·0% to groups of two male and two female beagle dogs for 2 yr. Ten of the 12 dogs fed Guinea Green B survived in good clinical condition. A male at 2% was killed after 1 yr when he became moribund and a female at 1% died after 5 months. Both non-survivors showed generalized inanition-type atrophy of the bone marrow, fat, skeletal muscle, adrenal cortex, lymphatic tissue and the gastric mucosa. Moderate periportal fatty metamorphosis of the liver was observed in a male survivor on 2%. No clinical signs of toxicity were attributable to Light Green SF Yellowish. Gross changes attributable to this compound were greenish coloration of the retropharyngeal lymph nodes, mesenteric lymph nodes, kidney cortices and urine. Livers appeared slightly enlarged in the four dogs at the 2% level. Slight hepatic congestion was observed in two females, one each at the 1 and 2% levels. Slight orange granularity of the hepatic cell cytoplasm appeared in two males at 2%. Ten of the 12 dogs fed Fast Green FCF survived in good clinical condition. A control male died after 3 months and a control female which became moribund was killed after 3·5 months; both had canine distemper. The skin and hair, intestinal contents, lymph nodes, and urine appeared green in the test dogs. Green blobs of pigment in the tubular epithelium of the renal cortex were noted in a male at 2%. Slight interstitial nephritis and slight bone marrow hypoplasia were found in a female at 2%. Mice (strain C 3HeB/FeJ) were fed Guinea Green B, Light Green SF Yellowish or Fast Green FCF for 2 yr at dietary levels of 0·0, 1·0 and 2·0%. A total of 400 mice was studied for each colouring to determine a possible tumorigenic effect. Mice fed Guinea Green B at the 1% level had a high percentage of tumours; however, there was no statistically-significant difference in tumour incidence between the three dietary-level groups. Increased survival occurred at the 1% feeding level of Light Green SF Yellowish. Compared with control groups, the total tumour incidence of the lungs of all test groups was significantly raised and this indicated a possible mild pulmonary tumorigenic effect, but there was no increase in the incidence of either malignant lung tumours or of tumours in other organs. Mortality was increased at the 2% level of Fast Green FCF at 78 wk but no significant difference in mortality was observed among the three groups at 2 yr.