1H-Inden-1-one, 2,3-dihydro-5,6-dimethoxy-3,3-dimethyl-2-(phenylmethylene)-

Endpoint summary

Description of key information

LD50 (rat), oral:   > 2000 mg/kg b.w.   (OECD 423 / EC B.1, GLP); limit test

Additional information

Acute toxicity, oral:

Acute oral toxicity in rat was assessed by the acute toxic class method. After a single oral application of 2000 mg/kg bw (6f), mild signs of toxicity were observed. These included (I) hunched posture and piloerection in one animal after one hour, and (II) hunched posture, lethargy, pilo-erection and decreased respiratory rate in all three animals of each group after 4 hours. At observation day 2 no signs were noted.

 

Acute toxicity, dermal:

No study on acute dermal toxicity is available for SymHelios1031. Testing is not considered to be required since testing on irritation/sensitisation show no potential for systemic toxicity. The LD50 is assumed to be above 2000 mg/kg bw.

 

Acute toxicity, inhalation:

Despite extensive efforts, a suitable test substance atmosphere (ideally 5.1 mg/L) could not be generated. This was tested in the forefront of animal inhalation testing. Instead, the test substance precipitated directly behind the outlet of the rotating brush dust generator. Consequently, testing on acute inhalation toxicity according to OECD 436 is considered not to be required, since it is technically not feasible. On the basis of a dustiness testing (modified Heubach method) a MPPD modelling (appendix I) shows that only minimal amounts penetrate to the deep lung tissue, whereas the overwhelming bulk of inhaled material is cleared rapidly to the GI tract, where oral bioavailability will determine its uptake.

Due to the reasons given above acute inhalation toxicity testing of SymHelios 1031is neither technically feasible nor scientifically relevant for this type of compound. Due to the particle size, the low mobility and the negligible volatility, the test material “SymHelios 1031” can safely be assumed to have a very low potential for human inhalation hazard during handling or application.

 

Justification for classification or non-classification

Based on the particle size, the low mobility and the negligible volatility the test material “SymHelios 1031” can safely be assumed to have a very low potential for human inhalation hazard during handling or application. Furthermore, due to the absent of any potential systemic toxicity in irritation/sensitisation animal studies acute dermal toxicity through human skin application could be excluded. The experimental study on acute oral toxicity results in an LD50 of 5000 mg/kg bw. In conclusion, the substance has not to be classified according to regulation (EC) 1272/2008.

 

Specific target organ toxicant (STOT) – single exposure: oral

The classification criteria according to regulation (EC) 1272/2008 as specific target organ toxicant (STOT) – single exposure, oral are not met since no reversible or irreversible adverse health effects were observed immediately or delayed after exposure and no effects were observed at the guidance value, oral for a Category 1 classification of 300 mg/kg bw and at the guidance value, oral for a Category 2 classification of 2000 mg/kg bw in addition to this effects which were responsible for the death of the animals. No classification required.