DL-α-methylbenzylamine

Endpoint summary

Description of key information

Based on the results of the acute oral toxicity study as well as on physico-chemical properties DL-α-methylbenzylamine is expected to be bioavailable via oral, dermal and inhalation route. Tissue destruction is a consequence of the strong basic properties of the substance. Once systemic available D- and L-α-methylbenzylamine are assumed to be widely distributed in the organism due to their small size and water solubility. The compounds might be deaminated to ammonia and acetophenone, which in turn might be reduced to 1-phenylethanol. Further oxidation and conjugation of the side chain facilitate renal excretion. No or only little variations in the kinetic profile are expected for the enantiopure D- and L-form of the substance. Based on the low log Pow value of the test substance no bioaccumulation is expected.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

Toxicokinetic analysis DL-alpha-methylbenzylamine

 

The test item is a colourless to pale yellow liquid at room temperature with a pH value of 12 and boiling point of 188.1°C. It has a molecular weight of 121.1796 g/mol, a density of 0.95 g/cm³ (21 °C) and a log Pow value of 1.31 (25 °C). The substance has a vapour pressure of 0.56 hPa (20 °C) and is soluble in water (42 g/L at 20 °C). DL-α-methylbenzylamine is a racemic mixture of D- and L-α-methylbenzylamine.

 

Exposure to DL-α-methylbenzylamine might occur via dermal and inhalation route.

 

In an acute oral toxicity study with the test item in rats (BASF SE, 2012) the LD₅₀ was determined to be between 300 and 2000 mg/kg bw for male and female rats. All animals of the 2000 mg/kg bw test group died immediately after administration. The macroscopic pathological findings revealed red discoloration in all lobes of the lung, dark discoloration of the liver and extensive bleeding in the glandular stomach. No mortality occurred in both 300 mg/kg bw test groups. Clinical signs like dyspnoea, piloerection and an impaired general state were observed. There were no macroscopic pathological findings in the animals of both 300 mg/kg bw test groups sacrificed at the end of the observation period.

In an EpiDerm™ skin corrosion test (BASF SE, 2012) DL-α-methylbenzylamine showed a corrosive potential.

There are no indications of genotoxicity of the test item and its metabolites from the present bacterial reverse mutation assay and the in vitro mutation assay on mammalian cells (BASF SE, 1997, 2012).

 

Absorption

After oral administration DL-α-methylbenzylamine is assumed to dissolve in the gastrointestinal fluids and absorption via aqueous pores or carriage across membranes with the bulk passage of water might occur as indicated by the water solubility. In addition, absorption of the substance via passive diffusion might be favoured due to the log Pow value of 1.31. The LD₅₀evaluated in an oral acute toxicity study indicates that the compound becomes bioavailable after oral administration.

Both, penetration into the stratum corneum and transfer into the epidermis is likely to occur based on the molecular weight, the water solubility and the log Pow value of the test substance. Due to the strong basic properties of DL-α-methylbenzylamine tissue destruction was observed at the sites of first contact in the acute oral toxicity study as well as in the human skin model resulting in an enhanced oral and dermal absorption.

Due to the vapour pressure of 0.56 hPa the test substance might become available for inhalation. As indicated by the molecular weight and the physico-chemical properties the test substance might cross the respiratory tract epithelium by passive diffusion or active transport via aqueous pores.

Taken together, experimental data and physico-chemical properties indicate bioavailability of the test substance via oral, dermal and inhalation route. Regarding absorption no difference between the racemic mixture and the enantiomers is expected due to identical physical properties.

Distribution

As D-and L-α-methylbenzylamine are small, water-soluble molecules, a wide distribution of the substances in the organism is expected. Cellular uptake is assumed due to their slight lipophilic properties. This assumption is supported by the adverse effects observed in all lobes of the lung and in the liver after oral administration. Extensive bleedings in the glandular stomach are attributed to the strong basic properties of the substance.

Based on the log Pow value and the water solubility of the test substance no bioaccumulation is expected.

Metabolism

The test substance might be deaminated to ammonia and acetophenone, which in turn might be reduced to 1-phenylethanol. Oxidation or conjugation of the side chain leads to 1-phenyl-1,2-ethanediol, mandelic acid and phenylglyoxylic acid. Ammonia is expected to be cleared by standard physiological pathways.

DL-α-methylbenzylamine and its metabolites are expected not to be genotoxic and metabolic activation is unlikely to occur. Metabolic turnover might be varying between the D- and L-form of the substance.

Excretion

D- and L-α-methylbenzylamine and its potential oxidised or conjugated metabolites are estimated to be renal excreted due to their low molecular weights and high water solubility.

 

Conclusion

Based on the results of the acute oral toxicity study as well as on physico-chemical properties DL-α-methylbenzylamine is expected to be bioavailable via oral, dermal and inhalation route. Tissue destruction is a consequence of the strong basic properties of the substance. Once systemic available D- and L-α-methylbenzylamine are assumed to be widely distributed in the organism due to their small size and water solubility. The compounds might be deaminated to ammonia and acetophenone, which in turn might be reduced to 1-phenylethanol. Further oxidation and conjugation of the side chain facilitate renal excretion. No or only little variations in the kinetic profile are expected for the enantiopure D- and L-form of the substance. Based on the low log Pow value of the test substance no bioaccumulation is expected.