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Description of key information

There are no toxicokinetic studies available.

Therefore a toxicokinetic assessment was prepared based on the physico-chemical properties of the substance and the available toxicological studies.

Key value for chemical safety assessment

Bioaccumulation potential:
low bioaccumulation potential

Additional information

Toxikokinetics of chinizarin (1,4-dihydroxy-9,10-anthraquinone, CAS no 81-64-1):

Physicochemical data as well as toxicological studies indicate a low bioaccumulation potential of 1,4-dihydroxy-9,10-anthraquinone (CAS no 81-64-1).

1,4-dihydroxy-9,10-anthraquinone is an organic solid of yellow red or dark red colour. The substance is an anthraquinone derivative with 2 hydroxyl groups in 1,4 position. The molecular weight is 240.2 g/mol. The determined melting points were in the range of 187 - 202°C and the vapour pressure of the substance is 0.000133 Pa at 25°C. The experimental determined pKa value for the substance was 9.51 at 18°C. Based upon its pKa, the substance exists mainly in its non-dissociated form at pH (1 -9).

1,4-dihydroxy-9,10-anthraquinone has a water solubility of 0.0961 mg/L at 25°C and the average partition coefficient (log Pow) was determined to be 4.2 at 25 °C (pH 5.3). Substances with a log Pow > 4 are not favourable regarding oral/GI absorption, respiratory absorption and dermal absorption. Absorption via micellular solubilisation cannot be excluded in the GI tract and the respiratory tract based on the high lipophilicity and low water solubility.

In 3 acute oral toxicity studies a LD50 > 5000 mg/kg bw was found. None of the animals died at a single oral dose of 5000 mg/kg bw. Signs of intoxication were a decrease of the general condition. In the acute dermal toxicity study none of the animals died after application of 2500 mg 1,4-dhihydroxy-anthraquinone. No signs of intoxication were observed.  No study for acute inhalaton toxicity is available.

No studies are available for repeated dose toxicity (sub-acute, sub-chronic, chronic and carcinogenicity) and toxicity to reproduction.

In all available studies for skin irritation/corrosion and eye irritation, 1,4-dihydroxy-9,10-anthraquinone was not irritating. In a guinea pig maximization test, 1,4-dihydroxy-9,10-anthraquinone was not sensitising.

1,4-dihydroxy-9,10-anthraquinone was positive in the Ames tests in some strains with  and without metabolic activation. 1,4-dihydroxy-9,10-anthraquinone was positive in a chromosomal aberration test in CHL/IU cells with and without metabolic activation. In an in-vitro MNT 1,4-dihydroxy-9,10-anthraquinone was positive in the presence and absence of metabolic activation. In these key-studies, therefore no indication for a metabolic transformation or degradation of 1,4-dihydroxy-9,10-anthraquinone was found.

Taken together, there were no relevant adverse effects of 1,4-dihydroxy-9,10-anthraquinone for acute oral and dermal toxicity in male and female rats up to 5000 mg/kg bw for oral toxicity and 2500 mg/kg bw for dermal toxicity. Based on the low vapour pressure of the substance, exposure via inhalation is unlikely.

Overall, based on the physicochemical date, very low water solubility and high octanol-water partition coefficient and based on the acute toxicological studies, limited absorption and a low bioaccumulation potential can be expected of 1,4-dihydroxy-9,10-anthraquinone.