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Description of key information

The acute toxicity of octylphosphonic acid (OPA) has been studied by oral and dermal routes. For oral toxicity, the study by HOEC (1979) (Rel. 2) in rats has been chosen as key study. Based on the results of this study, OPA is classified into category 4, H302 according to EU Regulation criteria. The key study for dermal toxicity (Rel. 1) is Allen (1997). No study on acute inhalation toxicity is required since the substance is a waxy solid with very low vapour pressure, and is corrosive to the skin.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LD50
Value:
1 890 mg/kg bw
Quality of whole database:
The study is a GLP compliant and has Klimisch score 2

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no study available

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Quality of whole database:
The study is a GLP compliant and has Klimisch score 1

Additional information

Oral Toxicity

In the key study Hoechst (1979) in female rats, the LD50 was 1890 mg/kg bw. Macroscopic examination of the decedents showed thickening of the stomach, stomach ruptured, substance in the abdominal cavity, suprarenal bodies discolored dark-red/brown, reddened gastric mucosa. No macroscopic effects or effects on bodyweight gain were seen in survivors. The LD 50 for female was 1890 mg/kg bw.

In the supporting study by Guest (1993) the LD50 for male and female rats was > 2000 mg/kg bw. There was no evidence of systemic toxicity. The only effects noted were white thickening of approximately one half of the area of the no glandular epithelium of the stomach, indicative of the corrosive effects of the test substance.

Dermal Toxicity

In the key study by Allen (1997), the dermal LD50 value in rats was > 2000 mg/kg bw. No systemic toxicity was reported but irritant effects persisted to the end of the observation period.

 

Inhalation Toxicity

No study on acute inhalation toxicity is required since the substance is a waxy solid with very low vapour pressure (1.6E-04 Pa at 25 °C), and is corrosive to the skin (Cat1B, H314).

 


Justification for selection of acute toxicity – oral endpoint
The reliability of the study in K2, in accordance with GLP and guideline. Based on the results of this study, OPA is classified into category 4, H302.

Justification for selection of acute toxicity – inhalation endpoint
Waiver

Justification for selection of acute toxicity – dermal endpoint
Only one study available

Justification for classification or non-classification

Oral:

As the LD50/rat females is 1890 mg/kg bw, OPA is classified for acute oral toxicity into category 4, H302 according to the regulation (EC) N°.1272/2008 and as Xn R22 according to the Directive 67/548/EEC criteria.

Dermal:

The limit value for classification of a substance as harmful on acute exposure by the dermal route according to the criteria of Annex VI Directive 67/748/EEC (R21) and the regulation (EC) N°.1272/2008criteria (Acute toxicity Cat. 4) is dermal LD50 2000 mg/kg. The available study on OPA gives LD50 > 2000 mg/kg. OPA is therefore not classified for acute dermal toxicity according to the regulation (EC) N°.1272/2008 and the Directive 67/548/EEC criteria.

Inhalation:

No study on acute inhalation toxicity is available or required. No classification is possible due to lack of data