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Environmental fate & pathways

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Phenethylammonium salt of fosfomycin is expected to be very stable in the environment.

Water.

In water no degradation is expected according to the results of the hydrolysis and of the ready biodegradation test. Indeed, at pH 9 (120 h at 50 °C) the hydrolysis was < 3.4%, while at 28 days biodegradation of Fosfomycin Pea Salt was 0% (not readily biodegradable).

Soil.

Phenethylammonium salt of fosfomycin is an organic salt, freely soluble in water, which dissociates into fosfomycin ((3-methyloxiran-2-yl) phosphonic acid)) and phenethylammonium ions within the environmentally relevant pH range (5-8). Experimental Log Koc for phenethylammonium is 4.54. Fosfomycin anion has weak UV absorption and was not detectable at the selected wavelenght in the absorption study, then its Koc has been estimated by KOCWIN v2.00 (US EPA): calculated values of Log Koc for non-ionized fosfomycin are 0.09 (estimate from Log Kow) and 0.07 (estimate from MCI); Koc value for fosfomycin anion is not expected to be significantly different from its non-ionized form.

High mobility in soil is therefore expected for the fosfomycin anion, while pour mobility is expected for phenethylammonium.