Melamine

Endpoint summary

Description of key information

Melamine has a low acute toxicity by the oral, dermal and inhalation route.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

3 161 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Value:

mg/m³ air

Additional information

Per oral application: 4 studies on the acute oral toxicity in rats are available and 2 with mice. Each study result provides an LD50 > 3000 mg/kg bw. The most reliable study, the NTP study, was selected as the key study. It reports an LD50 = 3161 mg/kg bw for male rats, and slightly higher for females.

Inhalation route: Only one study (Muijser 1988) is considered to be sufficiently reliable. The LC50inhalation,rat >5190 mg/m3 (a value that can not be entered in the field above). The other two studies are insufficiently described and not sufficiently reliable, leaving the method of generation of the test substance-air mixture unclear in Ubaydullayev 1993, and not reaching a high enough concentration in the study of Hofmann 1969.

Dermal exposure: The study is waived, applying the REACH criteria: "Testing for acute toxicity by the dermal route is appropriate if: (1) inhalation of the substance is unlikely; and (2) skin contact in production and/or use is likely; and (3) the physicochemical and toxicological properties suggest potential for a significant rate of absorption through the skin."

Criteria (1) and (3) are not fulfilled, therefore testing is not appropriate. Criterion (1): Inhalation is not unlikely and an investigation of the acute toxicity by inhalation was performed, see 7.2.2. Criterion (3): Melamine has a low acute oral toxicity, see 7.2.1., it is therefore and because of the expected low dermal absorption unlikely that the acute dermal toxicity exceeds the oral toxicity. The low dermal absorption is estimated from the low partition coefficient, see Section 7.1.2.

The available old study on the acute dermal toxicity reporting an LD50dermal,rat of >1000 mg/kg bw (a value that can not be entered in the field above) supports the estimated low acute dermal toxicity.

Justification for classification or non-classification

No classification due to acute toxicity of melamine is required, because:

The LD50oral,rat >3000 mg/kg bw.

The LC50inhalation, rat >5190 mg/m3.

The determination of the LD50dermal,rat is waived; but based on the low acute oral toxicity and the low estimated skin penetration of melamine, the LD50dermal,rat is considered to be >2000 mg/kg bw. This is supported by an old study yielding an LD50dermal,rat >1000 mg/kg bw.