Biphenyl

Endpoint summary

Description of key information

Acute toxicity oral:
The reliability of all available studies was not assignable (Klimisch 4). A weight of evidence approach is followed using all these studies. The rat LD50 for biphenyl ranged between 2180 mg/kg bw and 5040 mg/kg bw.
Acute toxicity inhalation:
The reliability of all available studies was not assignable (Klimisch 4). Acute inhalation studies of Haley et al. (1959), Birch (1976), Younger (1959) and Shewbart (1974) were used in a weight of evidence approach. Only unbounded effect concentrations were available. The highest LC50 value in rats was > 3.47 mg/L (1 hour of exposure).
Acute dermal toxicity:
Here also, the reliability of all available studies was not assignable (Klimisch 4). The two available studies (Birch, 1976; Rampy et al., 1974) were used in a weight of evidence approach. Only unbounded effect concentrations were available. The highest LD50 value (for New Zealand White rabbit) was > 5010 mg/kg bw.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

acceptable

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

acceptable

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

acceptable

Additional information

Acute oral toxicity:

Only Klimisch 4 studies were identified. A weight of evidence approach is followed using all available studies. The rat LD50 for biphenyl ranged between 2180 mg/kg bw and 5040 mg/kg bw.

Acute inhalation toxicity:

Biphenyl is a solid, with a melting point of 69 degrees celcius and a vapour pressure of approximately 1 Pa at 25 degrees celcius. Based on these properties, and the fact that the particle size is >100 micrometers and therefore the possibility for an acute inhalation exposure to a vapour or aerosol (liquid or solid) is minimal. As such data on acute inhalation toxicity are not required according to Annex VIII, Column 2 of the REACH text.

Irrespective of its physical chemical properties there are inhalation toxicity studies available for biphenyl. The studies are minimally reported and involved the exposure of test animals to a vapour created by heating the test material. As such the reliability of all available studies was not assignable (Klimisch 4). Acute inhalation studies of Haley (1959), Birch (1976), Younger (1959) and Shewbart (1974) could be used to determine unbounded LC50 values and were used in a weight of evidence approach as only limited information on methods and results were reported. The highest LC50 value in rats was > 3.47 mg/L (1 hour of exposure) as reported by Haley (1959). No higher concentrations of biphenyl were tested. The remaining studies did not specify test concentrations and are used as supporting evidence.

Based on the available data and the fact that biphenyl is a solid, additional studies to characterise the acute inhalation toxicity are not appropriate.

Acute dermal toxicity:

The two Klimisch 4 studies are used in a weight of evidence approach. Rampy et al (1974) reported a 24 hours LD50 value for biphenyl, tested on New Zealand White rabbit, which is > 3980 mg/kg bw. The only signs of toxicity noted were topical effects which included slight to moderate erythema and slight edema at the site of application. Birch (1976) reported a 24 hours LD50 value of > 5010 mg/kg bw for the same rabbit species.

Justification for selection of acute toxicity – oral endpoint
a weight of evidence approach was used - no single key study is assigned

Justification for selection of acute toxicity – dermal endpoint
a weight of evidence approach was used - no single key study is assigned

Justification for classification or non-classification

- Based on the available information the LD50 for acute oral toxicity is higher than 2000 mg/kg bw and consequently no classification for acute oral toxicity is warranted according to the CLP criteria.

- Based on the physical properties of the substance and the available inhalation toxicity information (K4 studies) demonstrating a low order of toxicity at the highest vapour concentrations assessed, classification for inhalation toxicity is not required

- Based on the available information the LD50 for acute dermal toxicity is higher than 2000 mg/kg bw and consequently no classification for acute dermal toxicity is warranted according to the CLP criteria.