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Description of key information

Key value for chemical safety assessment

Additional information

There are no studies available in which the toxicokinetic behaviour of any member of the Vinasses chemical category has been investigated.

Therefore, the assessment of toxicokinetics of Vinasses is conducted on a qualitative basis taking into account the available information on substance definition as well as physicochemical and toxicological characteristics according to Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance (ECHA, 2008).

All members of the Vinasses category share a common origin and production process. Vinasses are by-products of a fermentation process, at the end of which the target fermentation product(s) and, if applicable, the micro-organism biomass are removed from the fermentation broth by appropriate methods. Vinasses are contained in the resulting liquid, which is usually concentrated by physical means.

Since Vinasses result from a controlled fermentation processes involving complex biological raw materials and different micro-organisms, they are regarded as typical substances of unknown or variable composition of biological origin (UVCB). Based on dry matter content, Vinasses are mainly composed of biological macromolecules (primarily proteins, but also sugars and lipids) and ash residue which includes mineral salts of both biological (from the raw materials) and non-biological origin (added during the production process), particularly potassium and sodium salts (sulfates).

Absorption, distribution, metabolism and excretion of biomolecules (proteins, sugars, lipids) have been extensively studied, are well-understood and adequately described in the relevant literature (Despopoulos, A and Silbernagl, S., 2001; Elmadfa, I. and Leitzmann, C., 2004; Löffler, G et al., 2007; Rehner, G. and Daniel, H., 2002; Karlson, P and Doenecke, D., 2005). It is outside the scope – and not the aim – of this assessment to reproduce this information in the present context. Where applicable, supporting information on biomolecules is shortly discussed along with substance specific data. The same approach applies to relevant mineral salts in Vinasses, particularly potassium and sodium sulfates.

 

Absorption

Oral

- Relevant physicochemical parameters:

As expected for substances of biological origin, Vinasses contain both water soluble and insoluble material. For Vinasses, residue of fermentation containing biomass of Corynebacterium glutamicum, around 30 to 40 % (w/w) of dry matter is composed of material with a relatively high water solubility (Oudhoff, 2010).

Water soluble substances will readily dissolve into the gastrointestinal fluids, and compounds of low molecular weight (less than 200) may pass through aqueous pores or be carried through the epithelial barrier of the gastrointestinal tract by the bulk passage of water. Lipophilic compounds may be taken up by micellar solubilisation.

- Relevant toxicological characteristics:

No relevant information on the absorption potential of Vinasses can be obtained from the available oral toxicity data. Vinasses have been tested in acute oral toxicity studies, resulting in LD50 values greater than 5000 mg/kg bw without signs of toxicity. The very low toxic potential of Vinasses via the oral route has been confirmed in subacute and subchronic studies in rats, in which systemic effects were observed only at high dose levels: In an oral prenatal developmental toxicity study in rats, the LOAEL for maternal toxicity was 8700 mg/kg bw/day based on decreased body weight and food consumption, which both can be attributed to the high ammonium content of the test substance (Wolterbeek, 2003); in a subchronic oral toxicity study in rats, treatment-related effects were observed at the highest dose level tested (8000 mg/kg bw/day in males and 9600 mg/kg bw/day in females) consisting of a decrease in plasma chloride in females and an increase in relative liver weight in animals of both sexes. These changes were, however, minor and not associated with any histopathological changes (Appel, 2003).

Moreover, Vinasses are used as feed material due to their high protein content. The effects of partially or entirely replacing soybean meal by Vinasses as protein source in feed has been investigated in a number of studies in different livestock species.

Overall, no effects on growth and slaughter performance and no indications for toxicologically relevant changes were reported after feeding Vinasses, residue of fermentation containing biomass of bakers yeast (Saccharomyces cerevisiae) to young female goats at 2526 and 4995 mg/kg bw/day for 6 months (Ringdorfer, 2009); to dairy cows at 640 and 1296 mg/kg bw/day for 12 weeks (Urdl and Schauer, 2009); to bulls at 2135 mg/kg bw/day for 356 days (Leitgeb, 2010); to pigs at 10428 mg/kg bw/day for 55 days and at 5245 mg/kg bw/day for further 45 days (Windisch and Schedle, 2010).

In chicks fed Vinasses at 8, 16 and 24 % in diet for 36 days, a significant decrease in growth and slaughter performance was observed at the highest concentration with slight evidence of dose-dependency (Windisch and Leitgeb, 2009). The corresponding Vinasses mean dose levels over the study period were 6438, 13197 and 20780 mg/kg bw/day. The decrease in daily body weight gain was correlated with a decrease in daily feed intake. The absolute weight of abdominal fat, heart, liver stomach and individual body parts determined at the end of the study was also significantly decreased at the highest dose level. However, except for breast, the corresponding relative weights were not reduced and even a slight dose-dependent increase was observed.

Taken together, the results of these feeding studies indicate that at least the protein fraction of Vinasses is digested, absorbed and metabolised as effectively as soybean protein without toxicologically relevant effects to livestock species.

This is consistent with a study in bulls and pigs, in which the digestibility of Vinasses components was investigated (Stemme et al., 2005). In bulls fed Vinasses at 14% in diet, digestibilities of Vinasses components were: organic matter 73.5%, crude protein 72.6% and N-free extract 52.3%. No effects on faeces quality were observed. In pigs fed 16% Vinasses, the digestibility of organic matter was 72.3%, of crude protein 71.8% and of N-free extract 74.6%. Digestibility values of organic matter and crude protein were reduced (61.6 and 57.7%, respectively) in pigs fed Vinasses at 43%. The authors stated that this effect might have been due to a reduced retention time of the chyme resulting from an osmotically driven diarrhoea related to an unexpectedly high sulfate content in the Vinasses used. The authors concluded that the use of Vinasses in bulls and pigs in small proportions is reasonable based on the organic matter digestibility of > 70%.

- Further information on constituents:

Proteins, lipids and carbohydrates are constituents of normal diet and essential for the physiological function of the organism. In general, these biomolecules are readily absorbed via the gastrointestinal tract after enzymatic degradation by endogenous proteases, lipases and amylases. However, Vinasses may also contain an enriched fraction of non-starch polysaccharides (NSP), which are in general poorly digestible (Windisch and Schedle, 2010).

Sodium is essential for the maintenance of the total body fluid homeostasis and the blood pressure. It is also a key ion for the osmotic balance between the intra- and extracellular fluid, resulting in the electrochemical gradient, amongst others, essential for neuronal function. Due to these roles, the body sodium level is regulated by hormones and ion-pumps on the cellular level. The absorption of sodium is very fast and almost complete.

Like sodium, potassium is also a key element in regulation of osmotic balance between cells and the interstitial fluid as well as in neuronal function. The cellular content is regulated by ion pumps, which pump 3 sodium ions out of the cell and 2 potassium ions into the cell, thus creating an electrochemical gradient over the cell membrane. The absorption of potassium is achieved by active transport and is fast and almost complete.

Sulfate is a constituent of the blood and as well as a metabolite of sulfur-containing amino acids. The absorption of sulfate depends on the amount ingested. Absorption of small amounts of sulfate from the gastro-intestinal tract occurs rapidly and almost completely.

In conclusion, based on the available information on composition, physicochemical parameters and toxicological characteristics, a high level of absorption is expected for Vinasses via the oral route.

 

Inhalation

Based on substance class and physicochemical properties of the main components, the absorption of Vinasses via the lung is expected to be lower than – and in the worst case equal to – the absorption via the gastrointestinal tract. As stated above, biomolecules in Vinasses are readily absorbed via the oral route and absorption is largely facilitated by enzymatic activity. This activity is, however, expected to be low or even lacking in the mucus lining fluid of the respiratory tract. Water-soluble salts might be absorbed through water pores or be retained in the mucus and transported out of the respiratory tract. Insoluble material (particles) of inhalable size (MMAD < 100 µm) will likely be cleared from the lung with the mucus and swallowed.

The physical state/appearance of Vinasses largely depends on the water content. As described at the beginning of this section, the primary produced Vinasses in liquid form resulting from the fermentation process is usually concentrated by physical means. Depending on the degree of concentration/drying and compression, this results in Vinasses as viscous liquid, slurry or paste and finally dry pelleted powder.

Vinasses in liquid form are used as fertilizers and applied on fields by spreading activities. Due to the high viscosity of the liquid, the formation of, and consequently the exposure to, aerosols or droplets of respirable size is not expected to occur and therefore considered not relevant for humans.

The available data on the particle size distribution of Vinasses as dry pelleted material indicate that most of the particles are larger than 100 µm, and thus not inhalable (Agroethanol; Brekelmans, 2010). Therefore, exposure to respirable particles (MMAD < 5 µm) is unlikely and considered not significant for humans.

Thus, inhalation is not a relevant route of exposure for Vinasses.

 

Dermal

Dermal absorption of Vinasses as whole substance is considered to be low to very low based on the following considerations:

- Relevant physicochemical parameters:

Vinasses exist both as viscous liquids and dry material. Liquids and substances in solution are more readily absorbed than dry particulates. Dry particulates need to dissolve into the surface moisture of the skin before absorption can begin.

Vinasses are composed of both relatively high water soluble and insoluble compounds. The water soluble components (particularly mineral salts) may be too hydrophilic to cross the lipid rich environment of the stratum corneum. Dermal uptake for these substances will be low. The less soluble components may be able to penetrate the stratum corneum, provided that they are lipophilic enough (e. g. lipids). However, partition from the stratum corneum into the epidermis will be limited again by the low water solubility.

- Relevant toxicological characteristics:

The available animal data indicate that Vinasses are not skin irritating. Based on the weight of evidence, the available animal and human data on skin sensitisation is inconclusive.

The available data on the acute dermal toxicity of Vinasses in rats indicated the occurrence of slight clinical signs on days 1 and/or 2 of the study. These effects are, however, considered to be due to animal handling rather than substance-related. This is supported by the lack of signs of intoxication reported in acute oral toxicity studies.

- Further considerations on constituents:

Vinasses are mainly composed of proteins and other biomolecules (carbohydrates, lipids). The dermal absorption of these compounds is considered to be much lower than the absorption via the oral route, as the latter is facilitated by and dependent on enzymatic activity in the gastrointestinal tract.

In conclusion, based on the available information on composition, physicochemical parameters and toxicological characteristics, a dermal absorption potential of individual components of Vinasses cannot be completely excluded but is expected to be low to very low when considering the substance as a whole and compared to the oral route.

 

Distribution

Orally absorbed components of Vinasses (dietary biomolecules as well as water soluble mineral salts, in particular potassium and sodium sulfate) are expected to be systemically bioavailable.

 

Accumulation

Vinasses as a whole are not expected to bioaccumulate. Orally absorbed dietary biomolecules in Vinasses are expected to undergo metabolic transformation according to their respective substance class (proteins, carbohydrates, lipids) and used as energy source or become an integral part of the organism. Thus, organic matter in Vinasses may accumulate in the body as structural elements of e. g. muscle or adipose tissue. This, however, is a desired consequence of the intentional use of Vinasses as feed material.

Orally absorbed mineral salts from Vinasses (containing potassium, sodium, sulfur and to a lesser extent phosphorus) are also expected to be retained in the organism as essential elements necessary for normal physiological functions. Except for elements becoming part of the bone tissue (phosphorus), most salts are, however, not expected to remain in the organism for longer periods of time, as they are continuously and effectively eliminated via the urine.

 

Metabolism

As stated at the beginning of this section, it is outside the scope and not the aim of this assessment to reproduce the extensively studied and well-established metabolic pathways of dietary biomolecules. Reference is made to the relevant literature (Despopoulos, A and Silbernagl, S., 2001; Elmadfa, and Leitzmann, C., 2004; Löffler, G et al., 2007; Rehner, G. and Daniel, H., 2002; Karlson, P and Doenecke, D., 2005).

The available feeding studies described above support the notion that the orally absorbed fraction of organic matter (especially proteins) in Vinasses is metabolised in accordance with its substance class.

Bioavailable mineral salts in Vinasses are not prone to undergo metabolic transformation.

 

Excretion

The non-digestible fraction of Vinasses will be excreted in the faeces.

Due to the variety of metabolic pathways which the orally absorbed organic matter from Vinasses may undergo, it is not possible to identify the most likely route of excretion. All major routes including urine, exhaled air, bile, breast milk, saliva/sweat and hair/nails are possible.

Elimination of sodium is very low since it is reabsorbed in the glomeruli of the kidney. Nonetheless, the main elimination route for sodium is via urine. For potassium, excretion occurs mainly via the kidney and only partly by faeces.

Regarding sulfate excretion, it was found that 30 - 44% was excreted in the 24-h urine of volunteers after oral administration of magnesium or sodium sulphate (5.4 g sulfate). At high doses that exceed the intestinal absorption potential, sulfate is excreted in faeces with possible cathartic effects. The sulfate levels are regulated by the kidney through a resorption mechanism, so that excess sulfate originated from the amino acid metabolisms is usually eliminated by renal excretion. The daily sulfate excretion is reported to be 0.20 to 0.25 mmol/kg bw/day and being higher in children (Health Canada, 1987 and 1994).

References:

Canada Health, November 1987 (updated September 1994), Sulfate. Available: http://www.hc-sc.gc.ca

Cocchetto, D.M. and Levy, G. (1981). Absorption of orally administered sodium sulphate in humans. J. Pharm. Sci. 70(3):331-333.

Despopoulos, A and Silbernagl, S. (2001). dtv-Atlas Physiologie.Die Funktionen des menschlichen Körpers. 14th ed. Deutscher Taschenbuch Verlag, München.

Elmadfa, I. and Leitzmann, C. (2004). Ernährung des Menschen. 4th ed. Eugen Ulmer, Stuttgart.

Karlson, P and Doenecke, D. (2005). Karlsons Biochemie und Pathobiochemie : [Falttafel mit Stoffwechselübersicht]. 14th ed. Thieme, Stuttgart.

Löffler, G et al. (2007). Biochemie und Pathobiochemie. 5th ed. Springer, Berlin Heidelberg New York.

Potts, W.T.W.; Parry, G. (1964).Osmotic and ionic regulation in animals. Pergamon Press.

Rehner, G. and Daniel, H. (2002). Biochemie der Ernährung. 2nd ed.Spektrum.