Perhydroazepine

Endpoint summary

Description of key information

Based on overall evaluation of the available data for acute oral toxiciyt in rats a oral LD50 in the range of 400 to 500 mg/kg bw seems warrantable. In rats a LD50 value of 2.77mg/L air was identified after single exposure to vapour containing the submission substance. Various studies of not assignable reliability indicate that the acute dermal LD50 value for the submission substance varies from > 200mg/kg up to 5010 mg/kg in rabbits.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

400 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

2 770 mg/m³ air

Additional information

Reported values for acute oral, eyes, inhalation, and dermal toxicity with HMI ranged from highly toxic to slightly toxic and are listed in Table 1 (see attachment).

There are several studies to test acute oral toxicity in rats.

However, only some studies specified the purity of the samples tested and were administered in diluted aqueous solutions (opposed to administering a pure compound that is known to be corrosive). In the first study (DuPont®, 1974a; i.e.endpoint study record Invista_Haskell_report no. 328 -74) an aqueous solution of HMI (purity 98.18%) was administered by intragastric intubation to male rats in single doses of 300, 450, 670, 1000, 1500, 2250, or 3400 mg/kg. Survivors were sacrificed after 14 days. The 24-hr acute lethal dose (ALD) was found to be 1000 mg/kg (slightly toxic), suggesting a 14-day LD50 ALD > 670 and < 1000 mg/kg.

Another oral toxicity study with rats from 1974 (i.e. endpoint stduy record Invista_Haskell_report no. 330 -74), but using HMI with a purity of 20% as test material, revealed an LD Lo of 2250 mg test material/kg bw.

Acute oral toxicity data for HMI was reported as part of a range-finding study of combined repeated dose toxicity with reproductive and developmental toxicity screening report (OECD 422 [INVISTA® 2006b]; for results see study report included in section 7.8.1). In order to set the dose level, groups of 3 animals per sex received 5 daily doses of HMI (diluted with water). On the first day, one male and one female rat were administered HMI at 500 mg/kg via oral gavage. No lethality occurred, however, based on clinical signs (gasping, bloody mouth and nose area, lethargy, tremors, lethargy, etc.) animals were sacrificed and it was decided to decrease the dose to 400 mg/kg for the remaining 4 doses. No deaths occurred at 400 mg/kg but animals were killed in extremis on day 3 and 4 due to poor health. These data suggest an Oral LD50 in the 400 to 500 mg/kg range.

In a 1985 study (Rohm and Haas®, 1985), Male CRCD rats (6/dose level) were orally intubated with 0, 50, or 500 mg/kg HMI (reported as “neat material”). The rats were fasted overnight, prior to administration of the test material. Body weights and clinical signs were recorded, and all rats were necropsied. Mortality was reported to be 0/6, 0/6, and 6/6 at 0, 50, and 500 mg/kg, respectively. Mortality occurred on the day of dosing.

Clinical signs of toxicity in the control rats, observed on the day of dosing, included brown-stained anogenital area (2/6) and diarrhea (1/6). No clinical signs of toxicity were observed in rats dosed with 50 mg/kg. Clinical signs of toxicity observed at 500 mg/kg included passiveness (6/6), prostration (2/6), ataxia (6/6), tremors (3/6), convulsions (2/6), salivation (6/6), labored abdominal breathing (3/6), brown-stained anogenital area (1/6), ptosis (6/6), and cyanosis (2/6). No macroscopic changes were observed in rats dosed at 0 or 50 mg/kg. Necropsy observations noted at 500 mg/kg included red-stained eyes (2/6), wet matted fur on the muzzle (6/6), whitened lungs (5/6), severely reddened stomach mucosa and intestines (6/6), and red fluid-filled stomach and intestines (6/6).

Since only two doses were tested, these data did not define a LD50. However, deaths of all the animals in the high dose group (500 mg/kg) and having no lethality at 50 mg/kg, suggests a 24-hour LD50 between 50 and 500 mg/kg, the study design did not take into account the caustic nature of HMI.

In an earlier study (Monsanto® Co., 1973), HMI (reported as “refined”= 99% technical material) was evaluated for acute oral toxicity in rats. Doses of 3.98, 6.31, 10.0, or 15.8 mg/kg were administered undiluted by oral gavage. Mortality generally occurred within 8 days and resulted in an oral LD50 of 9.6 mg/kg. Although this study defined an oral 8 day LD50, the study design did not take into account the caustic nature of HMI.

Under the applied test conditions of another test (Zaeva, 1968) the test substance revealed a LD50 value of 32 mg/kg bw. As this study was only cited from secondary sources no information on test material composition or purity as well as further details on study design were available.

In summary, a LD50 of HMI is expected to be 400-500 mg/kg (INVISTA 2006b), >50-500 mg/kg (Rohm and Haas®, 1985), and a 14 -day ALD is < 1000 (DuPont®, 1974a). Studies reporting lower LD50 values are thought not to be reliable to evaluate acute oral toxicity as no information on test material composition or purity as well as further details on study design were available, and no information was available to conclude if the study authors paid attention to the caustic nature of the test material.

Since the majority of these studies were not 14 days in length (OECD Guideline) and some studies apparently used undiluted HMI, the 14-day Oral LD50 can be placed conservatively in the 400-500 mg/kg range.

In order to test for acute toxicity via inhalation several tests on rats and mice were performed. In rats under the applied test conditions (report no.495 -74) the test substance has an LC50 value of 2.77 mg/L air and the LCLo value is 2.45 mg/L air after a 4 h exposure. Another study (report no. 329 -74) in rats showed LC50 values which were higher than 2.3 mg/L air (test material a: 98 % HMI) or higher than 2.7 mg/L air (test material b: 20 % HMI) after 1 h exposure, as none of the tested animals died during the study (each test: 0/10). Recalculation for classification purposes leads to an LC50 value > 1.15 or >1.35 mg/L air for a four hour exposure period (according to Regulation (EC) No 1272/2008 for vapours divide the experimental data of the one hour exposure experiment by two to obtain data relevant for classification (i.e. 4 hour exposure). But as no mortality was observed no definite LC50 value could be established which would lead to classification.

Using mice there was a study which identified a LC50 value of 10.8 mg/L air after a 2 hour exposure period (Izmerov, 1982). In another study under the applied test conditions the test substance revealed a LC50 value of 10.5 mg/L air in mice (exposure period unknown; Bazarova, 1967).

Acute dermal toxicity was tested using new zealand white rabbits in three independent investigations. All of these studies were not reliable as the original study report was not available and they were only cited from secondary source. Moreover only in one study information on test material purity was given.

Hexamethyleneimine had a dermal MLD (Minimum Lethal Dose) of 1260-2000 mg/kg when tested in rabbits (Monsanto, 1973). The undiluted test substance was applied in increasing doses at increments of various fractional log intervals to the closely clipped, intact skin of male and female rabbits. The treated areas were covered with plastic strips, and the rabbits were held in wooden stocks for periods up to 24 hours. Observations were made for toxic signs, and the viscera of the test rabbits were examined macroscopically.

In an earlier study (report no. Y72 -114), HMI binary solution was evaluated for acute dermal toxicity in rabbits administered undiluted semi-occluded applications of 1000, 2000, 3160, and 5010 mg/kg upon clipped, intact skin for 24 hours. Clinical signs of systemic toxicity included reduced appetite and activity, increasing weakness, collapse, and death. Hexamethyleneimine was dermally corrosive and mortality occurred in a single female of a 5010 mg/kg dose, and a LD50 was reportedly between 3160 and 5010 mg/kg. (Monsanto Co., 1972).

Under the applied test conditions of the last study (24 h, occlusive) the test substance revealed a LD50 value of > 200 mg/kg (i.e. highest dose tested; Rohm and Haas, 1985).

Justification for classification or non-classification

Considering the data described above classification for acute oral a into category 4 is necessary according to Regulation (EC) No 1272/2008. Based on the results of the most reliable study for testing on acute toxicity after inhalation exposure calssification into category 3 is required according to Regulation (EC) No 1272/2008.

Concerning acute dermal toxicity only data with non assignable reliability evaluations was presented. Due to the lack of data no classification according to Regulation (EC) No 1272/2008 is propsed. Also, the test is not mandatory because of the corrosive nature of the product and HMI is an intermediate and needs only available data.

Based on the available toxicity data for inhalational substance exposure the submission substance has to be classified as Category 1 of Specific target organ toxicity after single dosing (STOT se 1) according to the limits set in Regulation (EC) No. 1272/2008.

According to Council Directive 76/548/EEC the submission substance hast to be classified as harmful if swallowed as well as harmful if inhaled based on the LD50 values presented.