Ammonium sulphate

Endpoint summary

Additional information

Acute toxicity to Eisenia fetida was tested in a study according to EPA/600/3-88/029 (1988) using Ammonium chloride as test substance (CAS: 12125 -02 -9). The 14d- LC50 value was 201 mg/kg soil (Yeardley et al. 1995, value related to Ammonium sulphate). Ma et al. (1990) studied long-term effects (20 yr) on nitrogenous fertilizers usage on lumbricid earthworms in soil. This study revealed that, Ammonium sulphate (5 applications per year of 60 -180 kg N/ha had effects on earthworm numbers and biomass. However, the effects were attributed to the lowering of pH observed in parallel with Ammonium sulphate application in the absence of liming. Long term applications of Ammonium sulphate had no negative effects with Collembolla and Cryptostigmata numbers increasing under 708 kg /ha/year application (Heneghan and Bolger 1996).

The most toxic results for specific soil bacteria, for cyanobacteria in rice fields, show less than 50% reduction in nitrogen fixation at 82.5 kg/ha/yr in the absence of liming (Fernández-Valiente et al., 2000). Similar results are seen for plants, with 471 kg/ha/y for 6 years affecting drought resistance in Picea abies (Rosengren-Brinck and Nihlgard 1995).

The effect of ammonium sulfate addition on the growth of the onion Allium cepa L. has been studied under laboratory conditions in 4 Canadian soils, in the presence of lime to raise the soil pH to approximately 6.5 (Abbes et al. 1995). After 84 days in a growth chamber, immature plants were harvested and fresh and dry weight of all plant parts were determined. Yield was greatest for 626 mg ammonium sulfate / kg soil (calculated from 133 mg N / kg soil). An inhibitory effect was found at 1880 and 2506 mg ammonium sulfate / kg soil (calculated from 399 and 532 mg N / kg soil), except for the sandy soil where only 2506 mg ammonium sulfate / kg soil was inhibitory. These inhibitory effects may be explained by salt effects.

No information on acute or chronic effects on birds is available. However, since the substance exhibits a low log Pow (see chapter 4.7), secondary poisoning is unlikely to be a relevant exposure route.

Conclusion:

Ammonium sulfate is used primarily as a nitrogen source in commercial fertilizer mixtures or as a direct application fertilizer, which accounts for > 90 % of the total amount (OECD 2007). Long term exposure of Ammonium sulphate significantly reduces soil pH, which in agricultural situations is controlled by liming. Therefore, a direct, uncontrolled exposure of ammonium sulphate to the terrestrial compartment does not take place. In addition, due to the rapid transformation of ammonium sulphate, an indirect exposure can be excluded. Inhibitory effects after repititive exposure of ammonium sulphate (as observed in the presented bacteria- and animal studies), were attributed to the lowering of soil pH, exlusively. Therefore, these studies were not considered for the derivation of PNECsoil. The study by Abbes et al. (1995) has been selected as the most reliable endpoint for a derivation of PNECsoil, since it was a) conducted under controlled conditions and b) since soil pH was controlled by liming. The application rate of 626 mg / kg Ammonium sulphate was used as NOEC.