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There were no studies available in which the toxicokinetic properties of 1,6-hexanedioldiacrylate (HDDA) were investigated.

 

1,6-Hexanedioldiacrylate having a molecular weight of 226.27 g/mol is a colourless to yellowish liquid, which is soluble in water (solubility: 0.36 - 0.48 g/l at 20 °C). It has a volatility of 0.0006 hPa at 20 °C and a log Po/wof 2.81 at 25 °C.

 

In an acute oral toxicity study, rats were administered 2150 and 5000 mg/kg bw 1,6-hexanedioldiacrylate by gavage. No clinical signs of toxicity were observed, but one out of ten animals of the 5000 mg/kg bw group died after seven days; therefore bioavailibility of 1,6-hexanedioldiacrylate is indicated (BASF 1979).

In an acute dermal toxicity study dose levels of 0.315, 0.795, 1.99 and 5.0 ml/kg bw 1,6-hexanedioldiacrylate were administered to rabbits (Litton Bionetics 1972). At 1.99 mg/kg bw one animal out of three died and at 5.0 mg/kg bw two out of four animals died, indicating bioavailability of 1,6-hexanedioldiacrylate also via the dermal route.

Bioavailability of the test material via the dermal route is confirmed, as the substance caused sensitization reactions after dermal application.

In a standardized inhalation hazard test with a saturated vapour atmosphere, 0/12 rats died after 7 h exposure (BASF 1979). Accelerated intermittent breathing, snout-wiping and unkempt fur were reported during and after exposure; at day 3 of observation, no more symptoms were seen and there were no necropsy findings in the survivors after a 14 d observation period, indicating a low toxicity potential of the substance if inhaled as vapour. When considering the vapour pressure of 1,6-hexanedioldiacrylate, the adsorption of the substance as vapour via the inhalative route can be assumed to be unlikely.

Based on the results of the described toxicity studies, an indication of oral or dermal uptake of 1,6-hexanedioldiacrylate is given. Therefore the bioavailablity can be considered to be existent.

 

Considering the chemical structure of 1,6-hexanedioldiacrylate, metabolism may consist of epoxidation of the acrylic double bond and subsequent hydrolysis and GSH conjugation, or of an oxidation at the C terminus to the acid followed by ß-oxidation involving degradation of the alkyl chain, or of an ester hydrolysis leading to the release of acrylic acid.

Taking into account the log Po/w, the water solubility and the considerations on the metabolism, accumulation of 1,6-hexanedioldiacrylate is considered to be unlikely.

Available data from a different group of “multifunctional acrylates”, the so-called “trifunctional acrylates” suggests that distribution to many different tissues is likely but accumulation is unlikely to occur as almost no substance was found to be left in the tissue and carcass 72h after application and fast elimination of the substance, mainly via urine, exhaled air and faeces, was reported. The structural similarities between HDDA and the “trifunctional acrylates” are still sufficiently large enough to assume that the observations made for the “trifunctional acrylates” concerning distribution, accumulation and excretion are also likely for HDDA.