Supernatant from the crystallisation of L-threonine from the broth filtrate from the fermentative production of L-threonine

Endpoint summary

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

As the toxicological database for L-threonine mother liquor itself is limited, additional data for the read-across substance Biofert Plusz are taken into further consideration. Based on the composition of Biofert Plusz (mixture of L-threonine mother liquor and modified waste) it can be assumed that the results obtained with Biofert Plusz apply likewise to L-threonine mother liquor.

The dry mass of L-threonine mother liquor consists of residual fermentation nutrients (salts, sugar and vitamins), and thermal degradation and reaction products of these substances.

 

Health characteristics of L-threonine mother liquor:

Neither the ingredients of L-threonine mother liquor nor their metabolites are regarded to be of toxicological concern, as comparable mixtures of substances are produced by the thermal treatment of food and feed stuff. This argument is substantiated by the complete absence of any adverse effects in acute and longer-term studies with oral application as well as in genotoxicity and developmental toxicity/teratogenicity studies (data for L-threonine mother liquor and/or Biofert Plusz). Also no adverse effects were seen in an acute dermal toxicity study performed with Biofert Plusz. L-Threonine mother liquor and also Biofert Plusz gave no indication for local irritating effects to the skin and the eyes and Biofert Plusz is not a skin sensitizer at the highest possible test concentration which is indicative for a low penetration rate of any ingredients as well as a negligible ability to bind to proteins.

No data are available for the inhalative route, but based on the available data for the oral and the dermal route no adverse effects are likely to be expected except a possible slight local irritating effect.

 

Absorption:

As for other natural occurring substances such as inorganic ions, sugars, lipids, proteins, amino acids, mono and polynucleotides and vitamins the bioavailability of L-threonine mother liquor via the oral route is expected to be high due to a common and regulated uptake mechanism. However, there is no toxicological concern based on the absence of any adverse effects in acute and longer-term studies with oral application (data for L-threonine mother liquor and/or Biofert Plusz). Also genotoxicity studies as well as the results from developmental toxicity/teratogenicity studies performed with Biofert Plusz gave no indication for adverse effects. Given the ionic nature of most organic and inorganic ingredients of L-threonine mother liquor the potential for skin penetration can be expected as low. Likewise the uptake via the respiratory tract is to be expected to be very low to negligible.

 

Distribution and Metabolism:

The distribution and metabolism of inorganic ions, sugars, lipids, proteins, amino acids, mono and polynucleotides and vitamins as contained in L-threonine mother liquor are very specific for each of these substance classes and completely different from the distribution and the metabolism of xenobiotics. A precise discussion on distribution and metabolism of all ingredients is not possible. Moreover, any unknown substances should be comparable or identical to ingredients of thermally treated food and feed stuff and therefore they should be of no toxicological concern. Their metabolism occurs probably through the classical pathways of xenobiotic metabolism (phase I, phase II) but will depend on the chemical nature and structure of the respective substance and thereby will be specific for this substance.

 

Excretion:

Like for absorption and metabolism specific regulated mechanisms for the excretion of inorganic ions, sugars, lipids, proteins, amino acids, mono and polynucleotides and vitamins and their metabolites exist in the human body. Inorganic ions are mainly excreted via the urine, but also via faeces. All other substance are partly or completely oxidised to CO2 and their metabolites (e.g. urea) are excreted via the urine or the faeces.

A precise statement on the excretion of all ingredients of L-threonine mother liquor based on the available data is not possible. If they degraded to small molecules < 300 g/mol, which are probably excreted via the urine and, if they are conjugated to glucuronic acids, they are probably excreted via the faeces.

 

Bioconcentration:

L-Threonine mother liquor is a mixture of different substances of diverse chemical nature with completely different kinetics for absorption, distribution, metabolism and excretion. Due to their natural origin only a general statement on the overall potential of bioconcentration for L-threonine mother liquor is scientifically possible. Since very specific degradation pathways exist for the single ingredients of L-threonine mother liquor a bioconcentration is not expected for the organic compounds. Additionally, also a bioaccumulation of the ionic substances (as the remaining nutrition salts) is not assumed due to their water solubility nature.