Ammonium chloride

Endpoint summary

Additional information

It is generally accepted, that the principal toxic component of ammonium salts such as ammonium chloride or -sulphate is ammonia, rather than the corresponding anion (see also: OECD 2004, SIDS ammonium chloride or OECD 2007 ammonium sulphate). Therefore toxicity values for ammonium salts (such as: ammonium -sulphates, phosphates, carbonates, chlorides or nitrates), where the major toxic component is ammonia, can be considered as equivalent. Consequently, this hazard assessment comprises the total topic of ammonia toxicity.

The application of ammonium salts as fertilizer is well established. The fertilising effect of ammonium chloride has been appreciated not only in China but also in India, USA, western and central europe and southeast asian countries such as Japan and Indonesia so on. It has been said that the paddy rice manured with this substance grows healthier, hard to be lodged and good for ripening. 

Acute toxicity to Eisenia fetida was tested in a study according to EPA/600/3-88/029 (1988) using ammonium chloride as test substance. The 14d- LC50 value was 163 mg/kg soil (Yeardley et al. 1995). 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 Collembola and Cryptostigmata numbers increasing under 708 kg /ha/year application (corresponding to 573 kg/ha/year Ammonium chloride; 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 66.8 kg/ha/yr in the absence of liming (value refers to ammonium chloride, Fernández-Valiente et al., 2000). Similar results are seen for plants, with 381 kg/ha/y for 6 years affecting drought resistance in Picea abies (value refers to ammonium chloride, 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 (corresponding to 508 mg/kg soil d.w. ammonium chloride, calculated from 133 mg N / kg soil). An inhibitory effect was found at 1880 and 2506 mg ammonium sulfate / kg soil (corresponding to 1525 and 1998 mg/kg soil d.w. ammonium chloride, calculated from 399 and 532 mg N / kg soil), except for the sandy soil where only 1998 mg ammonium chloride / 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:

Long term exposure of simple ammonium salts significantly reduces soil pH, which in agricultural situations is controlled by liming. Therefore, a direct, uncontrolled exposure of ammonium salts to the terrestrial compartment does not take place. In addition, due to the rapid transformation of ammonium salts, an indirect exposure can be excluded. Inhibitory effects after repetitive exposure of ammonium sulphate (as observed in the presented bacteria- and animal studies), were attributed to the lowering of soil pH, exclusively. 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 508 mg / kg ammonium chloride was used as NOEC.