Registration Dossier

Administrative data

Description of key information

The results for acute toxicity were read across from the stucturally analogous DTPMP-H (CAS 15827-60-8). In the key acute oral toxicity study (Younger Laboratories, 1971) a single dose of DTPMP was administered to by oral gavage to Sprague-Dawley rats (mixed sex 5/dose). Doses of 5010, 6310, 7940 and 10000 mg/kg bw were tested. The animals were then observed for seven days, after which they were examined macroscopically. There were 0, 2 (females), 3 (females) and 5 deaths at 5010, 6310, 7940 and 10000 mg/kg bw, respectively. Survival times were several hours to one day. Toxic signs included reduced appetite and activity, slight lethargy (lasting two to seven days in survivors), rapidly increasing weakness, collapse and death. Surviving female rats sustained weight loss over seven days. Males recovered initial weight loss and most showed weight gain. In animals that died there was slight liver discolouration and acute gastrointestinal inflammation. Seven days after administration the viscera of surving animals appeared normal at macroscopic examination. The LD50 was calculated to be 7180 mg/kg bw (equivalent to 4164 mg active acid/kg bw).
In the key acute dermal toxicity study (Younger Laboratories, 1971), DTPMP was applied to the clipped, intact skin of four New Zealand white rabbits, under an occlusive dressing, for 24 hours. Animals were then observed for 14 days, and all animals were examined macroscopically. No animals died and the LD50 was concluded to be greater than 7940 mg/kg bw (equivalent to >4605 mg active acid/kg bw). Toxic signs included reduced appetite and activity for one to two days after treatment. There were no abnormal macroscopic findings.
In accordance with Column 2 of REACH Annex VIII, the acute toxicity study via the inhalation route (required in Section 8.5.2) does not need to be conducted as reliable data via the oral and dermal routes are available.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LD50
Value:
7 180 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no study available

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
LD50
Value:
7 940 mg/kg bw

Additional information

Key studies were read across from DTPMP acid (CAS 15827-60-8) as well well as HMDTMP sodium salt (CAS 56744-47-9). The studies read across from DTPMP acid are pre-guideline and pre-GLP, but are comparable to OECD test guidelines and have therefore been given a reliability score of 2.

The studies for the HMDTMP sodium salt (CAS 56744 -47 -9) are described below. An acute oral LD50 value is estimated to be equal to >4875 mg/kg active acid in rat, in a reliable study conducted according to an appropriate protocol and in compliance with GLP (Safepharm 1982). The key study for acute dermal toxicity reports an LD50 value which is estimated to be equal to >3250 mg/kg active acid, in a reliable study conducted according to an appropriate protocol and in compliance with GLP (Safepharm 1982). DTPMP-H and HMDTMP sodium salt are structurally analogous to BHMT-H for which reason they were selected for read across. Results from both read across substances support the low acute toxicity of the registered substance BHMT-H (CAS 34690-00-1).

Justification for selection of acute toxicity – oral endpoint
The studies are pre-guideline and pre-GLP, but are comparable to OECD test guidelines.

Justification for selection of acute toxicity – dermal endpoint
The studies are pre-guideline and pre-GLP, but are comparable to OECD test guidelines.

Justification for classification or non-classification

Based on the available LD50 values from oral and dermal studies for the analogous substance DTPMP-H (CAS 15827-60-8) and HMDTMP (CAS 56744-47-9) which were used for read across, BHMT-H (CAS 34690-00-1) does not need to be classified for acute toxicity in accordance with Regulation (EC) No 1272/2008.