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Administrative data

Description of key information

A 2-year carcinogenicity study (NTP, 1987) equivalent to OECD Guideline 451 was carried out in mice. The study showed showed that boric acid was non-oncogenic by the oral route. The NOAEL is equivalent to 201 mg B/kg bw/day.

Key value for chemical safety assessment

Carcinogenicity: via oral route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
1 150 mg/kg bw/day
Study duration:
chronic
Species:
rat
Quality of whole database:
Comparable to guideline study with acceptable restrictions.

Carcinogenicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no study available

Carcinogenicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

No classification is required for boric acid regarding carcinogenicity as all results were negative.

Additional information

An OECD 451 equivalent study in B6C3F1 mice consisting of 50 per sex per group treated in diet for 103 weeks with 0, 2500 or 5000 ppm boric acid showed no evidence of carcinogenicity (NTP classification meaning no chemically related increase in benign or malignant neoplasms).

Based on the mouse NTP-study (1987) boric acid is not regarded carcinogenic. Although not carried out according to modern standards, nor to GLP, the 2-year studies in rats and dogs support this finding. While in the 2-year rat studies, only 10 animals/sex of the control and high-dose group were macroscopically and histologically examined, only 1-2 animals/sex/dose/time were examined in the 2-year studies in dogs, which limits the conclusions that can be derived from these studies. However, they were well performed and reported and are adequate to evaluate the carcinogenicity of boric acid and sodium borates. It can be concluded that boric acid and sodium borates are not carcinogenic and there is no concern for carcinogenic effects in humans.