D & C Yellow Nos. 10 and 11: delayed contact hypersensitivity in the guinea pig

Chemical-Induced Oral Squamous Cell Neoplasms in Rodents: An Overview of NTP 2-Year Cancer Studies

Oral cancer is the seventh most common malignancy worldwide, and lifestyle factors participate in its development. Rodent studies can help identify substances that contribute to its development and provide information on the early stages of carcinogenicity. The National Toxicology Program (NTP) has conducted more than 500 short-term and 2-year toxicology and carcinogenicity studies in rodents, and some of the tested compounds resulted in oral cancer. Our goal was to review the NTP carcinogenic studies to describe those chemicals that have oral carcinogenic outcome in rodents. For this project, we reviewed the results from all NTP carcinogenicity studies and a board-certified veterinary pathologist reviewed the slides from all neoplasms in the oral cavity that were considered treatment related. We have identified 26 chemicals with an adverse effect in the oral cavity. Fourteen chemicals demonstrated clear evidence of carcinogenicity in the oral cavity. We provide information on the carcinogenic findings in rodents together with a detailed description of the morphologic aspects of the oral cancers and speculate that the carcinogenic effects can be induced by different pathological modes of action. The findings reviewed here provide indicators for potential oral carcinogenesis processes in rodent models, which can be further investigated in future mechanistic studies.

An interlaboratory evaluation of the Buehler test for the identification and classification of skin sensitizers

The correct identification of potential skin sensitizers is an essential first step in enabling a proper risk assessment to be made and to permit the implementation of appropriate risk management practices designed to avoid the induction of sensitization. Consequently, regulatory guidelines around the world demand that new substances are evaluated to assess their skin sensitization potential. There are two guinea pig test methods which are generally recognised, the guinea pig maximisation test (GPMT) and the occluded patch test described by Buehler. In different countries, one procedure seems to be more prevalent and acceptable to regulatory authorities than the other. Notably, in the European Union, the latest revision of the Annex V (Directive 92/32/EC) Test Method for skin sensitization asks that justification should be given in the situation where the notifier does not use the GPMT, which is the preferred method. Thus in this paper, the validity of the Buehler protocol in the context of European legislation is critically examined. Results from two laboratories are collated, showing that the method can identify significant contact allergens, particularly those which would be registered formally as such according to European legislation. It is demonstrated that minor methodological variations can be tolerated without compromising test sensitivity, but it is recommended that suitable positive control testing is the best way to ensure proper test conduct.

Disposition of 2-(2-quinolyl)-1,3-indandione (D. C. yellow #11) in rats dosed orally or intravenously

The disposition of 2-(2-quinolyl)-1,3-indandione (D. C. yellow #11, DCY) in male Fischer rats dosed intravenously or by feeding was determined. For rats given [14C]DCY in the feed (0.00044-0.41% of the diet), recovery of radioactivity during the 24-h dosing period and the 72-h period thereafter ranged from 89.1 to 93.9% for feces and from 4.98 to 6.25 for urine. Tissues contained only trace amounts. Following intravenous dosing with [14C]DCY (0.93 mg/kg), radioactivity distributed readily into most tissues; maximum amounts were present at 5 min, the earliest time of assay. Maximum amounts of radioactivity in fat, skin, and gut tissue, however, were present at 30 min after dosing. These three tissues also had relatively long alpha phases for the elimination of radioactivity. In 24 h after intravenous dosing, rats excreted 81.1% of the dose in the feces and 16.0% of the dose in the urine. For rats fitted with biliary cannulas, 54.5% of the dose, all of which was metabolites of [14C]DCY, was recovered in the bile in 4 h. Associated with the rapid and extensive biliary excretion of metabolites of intravenously administered [14C]DCY was the appearance of large amounts of radioactivity in the feces and also, at intermediate time points, in the liver, gut contents, and gut tissue. In conclusion, rats rapidly distribute, metabolize, and excrete [14C]DCY.

D&C nos. 10 and 11: chemical composition analysis and delayed contact hypersensitivity testing in the guinea pig

D&C Yellow no. 11 was found to consist predominantly of quinophthalone together with other minor components, though not 6'-methylquinophthalone. Quinophthalone was found to be a strong sensitizer in guinea pigs by means of a modified testing technique, and its threshold concentration for induction and challenge was 10 ppm. Purified D&C Yellow no. 10, which was found to consist of 6 derivatives of sodium sulfonated quinophthalone, did not sensitize or elicit a cross-reaction in quinophthalone-sensitized guinea pigs even at a challenge concentration of 5%. Commercial D&C Yellow no. 10 contained 0.95-170 ppm of quinophthalone, and it is suggested that skin sensitization by D&C Yellow no. 10 is caused by contaminating quinophthalone.

The sensitization potential of D & C Yellow No. 11 in guinea pigs

The certified drug and cosmetic dye substance known as D & C Yellow No. 11 [2-(2-quinolyl)-1,3 indandione] was tested for its dermal sensitization potential in guinea pigs. An induction regimen consisting of a single footpad injection of Complete Freund's Adjuvant diluted with antigen, and an intradermal injection of antigen, produced delayed-type hypersensitivity reactions. A high sensitization frequency was observed with 50 micrograms D & C Yellow No. 11 and the positive control 2,4-dinitrochlorobenzene (DNCB). The reaction severities of both DNCB and 50 micrograms D & C Yellow No. 11 were comparable. A dose-response profile was obtained with D & C Yellow No. 11 employing several concentrations (50, 250 and 500 micrograms/ml). Histologic examination of selected skin sites demonstrated a cellular inflammatory response which was consistent with delayed-type hypersensitivity.

Dose response relationships in delayed hypersensitivity to quinoline dyes

Repeat insult patch testing of the quinoline dyes, D & C Yellow No. 10 (Acid Yellow No. 3) and D & C Yellow No. 11 (Solvent Yellow No. 33) demonstrated that concentrations as high as 1,000 ppm of the former induced no delayed contact hypersensitivity, whereas, concentrations of 20 ppm and 10 ppm of D & C Yellow No. 11 induced delayed hypersensitivity reactions in human volunteer panelists. No definitive hypersensitivity resulted from testing with 5 ppm of this dye. 2 persons who had been demonstrated to have reacted allergically to the use of a soap bar that contained D & C Yellow No. 11 did not react to the ad libitum use of a soap bar in which this dye was replaced with D & C Yellow No. 10.