N-1-naphthylaniline

Endpoint summary

Additional information

It can be concluded that hydrolysis is no relevant pathway or a pathway of minor importance for N-phenyl-1-naphthylamine from an environmental viewpoint. Photodegradation of N-phenyl-1-naphtylamine in aqueous solutions by sunlight is rapid and proceeds with a half-life of 5 to 8 min. Consequently, it is not expected to be present in surface waters in significant concentrations. However, this degradation rate may not necessarily be representative of an entire natural aquatic system. In most cases, depth, degree of mixing and season would be critical factors in determining the rate at which N-phenyl-1-naphtylamine is degraded by sunlight. One primary photoproduct was identified which is relatively photostable, probably the aniline adduct of 1,3-naphthoquinone.

N-phenyl-1-naphthylamine has shown to be not readily biodegradable in two biodegradation studies according to OECD 301C, yielding 0% degradation in both studies after 14 and 28 days, respectively. However, another study following recommendations of US EPA and measuring CO2 evolution, resulted in 50% degradation of N-phenyl-1-naphtylamine within 5 d in sewage effluent and >= 75% and 100% degradation within 2 and 10 d, respectively, in supplemented sewage sludge. For lake water, 50% degradation after 5 d and >= 90% degradation after 18 d were observed. The rate of biodegradation was enhanced in the presence of exogenous carbon and energy source, suggesting that the contribution of biodegradation will vary with the dissolved organic content of aquatic ecosystems. The presence of major metabolites was shown (95% of extractable radioactivity after 10 d), tentatively identified by GC-MS as dihydroxy derivative of N-phenyl-1-naphtylamine (m/e 252) and N-acetyl PNA (m/e 262).

Biodegradation of 14C-labelled N-phenyl-1-naphtylamine incarbon-supplemented soil resulted in 3.5% and 12.5% degradation after 2 and 11 days, respectively (unsupplemented soil suspensions: 6% and 22% after 2 and 11 days, respectively).Several studies on the bioaccumulation of N-phenyl-1-naphthylamine in fish and daphnids indicated a moderate to high bioaccumulation potential of the substance. It was shown that the substance accumulates in carp with BCF values ranging from 427 to 2490. Radiolabelled N-phenyl-1-naphtylamine was readily taken up in bluegill sunfish with bioconcentration factors of 600 for whole fish, 339 for edible flesh and 2063 for viscera. Half of the 14C-N-phenyl-1-naphtylamine-derived radioactivity in the fish was eliminated in about 2 days after transfer to clean flowing water, with about 50% of the radioactivity present as N-phenyl-1-naphtylamine metabolite(s). A major metabolite in the fish extract was identified as a dihydroxy derivative of N-phenyl-1-naphtylamine. The calculation of the log Koc yielded a value of 3.227, corresponding to a Koc value of 1685, indicating a moderate adsorption potential of the substance to soil and sediments.