Toxicity and biodegradation of products from polyester hydrolysis

Toxicity of products from polyester hydrolysis such as succinic acid (SA), adipic acid (AA), mandelic acid (MA), terephthalic acid (TA), 1,4-butanedio l (1,4-B), ethylene glycol (EG), styrene glycol (SG) and 1,4-cyclohexane di methanol (1,4-C) was evaluated by phytotoxicity test on germination of youn g radish seeds and by cytotoxicity test on HeLa cells. The phytotoxicity te st revealed SG > MA >1,4-C > AA approximate to SA > TA approximate to EG >1 ,4-B in order of decreasing toxicity taking into consideration the growth b ehavior after germination as well as the percentage of germination. Toxicit y on HeLa cells decreased in slightly different order compared to that on y oung radish seeds, i.e. SG > 1,4-C > MA > TA > SA > AA > EG > 1,4-B. Tests for the phytotoxicity and for cytotoxicity indicated that the aromatic comp ounds were more harmful than the aliphatic ones. Each group of 4 strains wh ich grew most rapidly on each agar plate containing SA, AA, MA, TA, 1,4-B, EC, SG and 1,4-C respectively as a sole carbon source was identified by the fatty acid methyl esters analysis. The modified Sturm test was carried out using the single isolated strain, an activated sludge or a mixed soil to m easure the rate of mineralization of the compounds into carbon dioxide. The aliphatic compounds were mineralized more easily than the aromatic compoun ds. 1,4-C showed the most exceptionaly slow degradation. A scrutiny of resi dual 1.4-C after degradation is required before polyesters containing 1,4-C could be classified into compostable because 1,4-C has detrimental effects on young radish seeds and HeLa cells and has a tendency to accumulate in t he environment due to its slow degradability.