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Toxicological information

Acute Toxicity: inhalation

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Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
other: extrapolation from results obtained by the oral route
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Extrapolation based on available guidelines on route-to-route extrapolation of toxicity data when assessing health risks of chemicals.

Data source

Reference
Reference Type:
other: extrapolation
Title:
Unnamed
Year:
2010

Materials and methods

Principles of method if other than guideline:
Extrapolation based on available guidelines on route-to-route extrapolation of toxicity data when assessing health risks of chemicals.
Test type:
other: extrapolation

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

Effect levels
Sex:
not specified
Dose descriptor:
LC50
Effect level:
> 25 mg/L air
Exp. duration:
4 h

Any other information on results incl. tables

Based on available guidelines on route-to-route extrapolation of toxicity data when assessing health risks of chemicals, an extrapolation based on the acute oral toxicity data is calculated for the inhalation route.

From the available data on the acute oral toxicity data, it is concluded that the oral LD50 for the substance Camphene is greater than 5000 mg/kg bw. As recommended in the corresponding guidelines, where data from the oral route is being used as the starting point, if no data are available on oral bioavailability, it is appropriate to assume that 100% of an orally administered dose is systemically available. Since no data is available on inhalation absorption, the most precautionary default would be to assume 100% absorption by this route.

Based on this acute oral toxicity data, an oral NOAEL may be identified as greater than 5000 mg/kg bw. This NOAEL can be modified into an inhalation NOAEL using a route-to-route extrapolation based on the assumptions stated above. Taking into account an exposure of 4 hours for the acute inhalation toxicity study, the value of 5000 mg/kg bw is divided by the default physiological parameter under the allometric scaling principle which is approximately 0.2 m3/kg bw for rats. This extrapolation leads to a value of 25000 mg/m3 (25 mg/l). Therefore, the 4 -h LC50 would be greater than 25 mg/l.

Applicant's summary and conclusion

Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Based on the assumptions for the extrapolation from the acute oral toxicity data, the inhalation 4-h LC50 would be greater than 25 mg/l.
Executive summary:

Based on available guidelines on route-to-route extrapolation of toxicity data when assessing health risks of chemicals, an extrapolation based on the acute oral toxicity data is calculated for the inhalation route.

From the available data on the acute oral toxicity data, it is concluded that the oral LD50 for the substance Camphene is greater than 5000 mg/kg bw. As recommended in the corresponding guidelines, where data from the oral route is being used as the starting point, if no data are available on oral bioavailability, it is appropriate to assume that 100% of an orally administered dose is systemically available. Since no data is available on inhalation absorption, the most precautionary default would be to assume 100% absorption by this route.

Based on this acute oral toxicity data, an oral NOAEL may be identified as greater than 5000 mg/kg bw. This NOAEL can be modified into an inhalation NOAEL using a route-to-route extrapolation based on the assumptions stated above. Taking into account an exposure of 4 hours for the acute inhalation toxicity study, the value of 5000 mg/kg bw is divided by the default physiological parameter under the allometric scaling principle which is approximately 0.2 m3/kg bw for rats. This extrapolation leads to a value of 25000 mg/m3 (25 mg/l). Therefore, the 4 -h LC50 would be greater than 25 mg/l.