Phthalate degradation

Taylor BF, JA Amador (1988) Metabolism of pyridine compounds by phthalate-degrading bacteria. Appl... 

Biological. Bis(2-ethylhexyl) phthalate degraded in both amended and unamended calcareous soils from New Mexico. After 146 d, 76 to 93% degraded (mineralized) to carbon dioxide. No other metabolites were detected (Fairbanks et al, 1985). In a 56-d experiment, [ C]bis(2-ethylhexyl) phthalate applied to soil-water suspensions under aerobic and anaerobic conditions gave CO2 yields of 11.6 and 8.1%, respectively (Scheunert et al, 1987). 

Biological. In anaerobic sludge, di-/3-butyl phthalate degraded as follows mono-/3-butyl phthalate to o-phthalic acid to protocatechuic acid followed by ring cleavage and mineralization. 

Biological. A proposed microbial degradation mechanism is as follows 4-hydroxy-3-methylbenzyl alcohol to 4-hydroxy-3-methylbenzaldehyde to 3-methyl-4-hydroxybenzoic acid to 4-hydroxyisophthalic acid to protocatechuic acid to p ketoadipic acid (Chapman, 1972). In anaerobic sludge, diethyl phthalate degraded as follows monoethyl phthalate to phthalic acid to protocatechuic acid followed by ring cleavage and mineralization (Shelton et al, 1984). 

Phthalates are easily released into the environment because there is no covalent bond between them and plastics in which they are mixed. The major portion of phthalates that are found in the environment comes from the slow releases of phthalates from plastics and other phthalate containing articles due to weathering. At natural conditions, phthalates are hydrolyzed to some extent yielding their corresponding monoesters, which are also environmental pollutants [15]. They show poor mobility in soil but aqueous leachates from landfills may contain trace amounts of more soluble products of phthalate degradation [11, 16]. 

All three phthalates degrade considerably worse under enviromnental conditions than they do in laboratory tests, however they caimot be classified on the whole as being persistent. The substitution of DEEP by DINP/DIDP in plastics for... 

Chang, H.-K. and G.J. Zylstra. 1998. Novel organization of the genes for phthalate degradation from Burkholdeia cepacia DBOl. J. Bacteriol. 180 6529-6537. 

Once released into the environment, phthalates degrade rapidly the half-life of DEHP (the most widely used phthalate) in water is only 2-3 weeks. But in air, or when bound to soil, phthalates can be stable for longer periods of time. The reported levels of DEHP, the most common phthalate, in air, water, and soil (see Table 7.6) illustrate this. As with other EDCs, phthalates are also ubiquitous in the environment and are present in the human body, breast milk, blood, and urine. In one study, over 75% of the US population were found to have phthalate metabolites in the urine (Stahlhut et al., 2007). This is hardly a surprise as the available data suggests life-long human exposure to occur from in utero through death of individuals. 

Enzymatic Degradation and Detoxification of Diethyl Phthalate by Fusarium oxysporum f. sp.pisi Cutinase... 

Kiyohara H, K Nagao, R Nomi (1976) Degradation of phenanthrene through o-phthalate by an Aeromonas sp. Agric Biol Chem 40 1075-1082. 

Ribbons DW, P Keyser, DA Kunz, BF Taylor, RW Eaton, BN Anderson (1984) Microbial degradation of phthalates. In Microbial Degradation of Organic Compounds (Ed DT Gibson), pp 371-395. Marcel Dekker, New York. 

The degradation of benzoate (Taylor and Heeb 1972 Williams and Evans 1975 Ziegler et al. 1987) and o-phthalate (Nozawa and Maruyama 1988 Afring and Taylor 1981). 

The degradation of isoquinoline by Alcaligenes faecalis strain Pa and Pseudomonas diminuta strain 7 (Roger et al. 1990, 1995) is mediated by an oxidoreductase that produces 1,2-dihydroiso-quinoline-l-one, followed by ring fission with the production of o-phthalate and oxidation to 3,4-dihydroxybenzoate (Figure 3.38). The oxidoreductase is purified and like most typical aza-rene oxidoreductases contains, per mole, 0.85 g atoms of Mo, 3.9 g atoms of Fe, and acid-labile S (Lehmann et al. 1994). 

C]-anthracene was used to study its degradation in soil, and the formation of labeled metabolites that could be released only after alkaline hydrolysis (Richnow et al. 1998). It was possible to construct a carbon balance during the 599-d incubation, and to distinguish metabolically formed phthalate from indigenous phthalate in the soil. 

Althongh the degradation of naphthalene-2-carboxylate by Burkholderia sp. strain JT 1500 involves the formation of 1-hydroxy naphthalene-2-carboxylate, this is not formed from the expected (l/ ,25)-di-l,2-dihydrodiol-2-naphthoate. Possibly, therefore, the reaction is carried out by a monooxygenase, or a dehydration step is involved. Subsequent reactions produced pyruvate and o-phthalate that was degraded via 4,5-dihydroxyphthalate (Morawski et al. 1997). Degradation of naphthalene carboxylates formed by oxidation of methyl groups has already been noted. 

The degradation of these was described many years ago (Evans et al. 1965), and details have since been added (Figure 8.10a) (van Herwijnen et al. 2003). Phenanthrene is more readily degraded than anthracene, and both can be degraded to o-phthalate. After hssion of the peripheral ring in phenanthrene, several pathways have been demonstrated ... 

---