1,2,3-Propanetriol, homopolymer

Endpoint summary

Description of key information

A theoretical approach is available which discusses polyglycerol-3. It is likely that the substance will completely absorbed via oral, dermal or inhalative exposure. Polyglyerol-3 can be used as a model substance for the other homopolymers of glycerin. All other homopolymers of glycerin should behave in a similar way. Natural glycerin itself, which is contained in the product, is expemted from REACH (see AnnexV).

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

100

Absorption rate - dermal (%):

100

Absorption rate - inhalation (%):

100

Additional information

TOXICOKINETIC ASSESSMENT

In general, a compound needs to be dissolved before it can be taken up from the gastro-intestinal tract after oral administration. The relatively small molecular weight (~240) and the high water solubility (>1000 g/L) of the major components indicates that uptake can take place through aqueous pores. However, the hydrophilic character of the major components (log Po/w -3.3/-3.9) will limit this passive diffusion. Overall, it is likely that Polyglycerol-3 is absorbed from the gastro-intestinal tract. For risk assessment purposes oral absorption of Polyglycerol-3 is set at 100%. The results of the toxicity studies do not provide reasons to deviate from this proposed oral absorption factor.

 

Once absorbed, distribution of the test substance throughout the body is expected based on its relatively low molecular weight, and accumulation in the body will be limited based on its hydrophilic character. Based on its hydrophilic character, extracellular concentration is expected to be higher than intracellular concentration. Absorbed Polyglycerol-3 might undergo conjugation. The conjugates will either be excreted via the bile (high molecular weights compounds) or the urine (low molecular weight compounds).

 

Due to the low vapour pressure (6.76 x 10^-6Pa) of the substance it is not to be expected that Polyglycerol-3 will reach the nasopharyncheal region or subsequently the tracheobronchial or pulmonary region. However, if Polyglycerol-3 reaches the tracheobronchial region no potential for absorption directly across the respiratory tract epithelium is expected due to its hydrophilic character (log Po/w -3.3/-3.9). However, based on its water solubility (>1000 g/L) and relative low molecular weight (~240) the substance may be retained within the mucus and subsequently absorbed through aqueous pores. Overall, although it is unlikely that Polyglycerol-3 will be available to a high extent after inhalation via the lungs due to the low vapour pressure. For risk assessment purposes the inhalation absorption of Polyglycerol-3 is set at 100%.

 

Polyglycerol-3 being a liquid has the potential to partition from the stratum corneum into the epidermis. Since the water solubility is above 10.000 mg/L (>1000 g/L) and the log Po/w below 0 (log Po/w -3.3/-3.9), the substance may be too hydrophilic to cross the lipid rich environment of the stratum corneum, and dermal uptake will be therefore low. As the criteria for dermal absorption as given in the TGD (MW > 500 and log P_ow< -1 or > 4) are not met, 100% dermal absorption of Polyglycerol-3 is proposed for risk assessment purposes. The results of the toxicity studies do not provide reasons to deviate from this proposed dermal absorption factor.