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Only little information on the terrestrial toxicity of ammonium hydrogencarbonate is available. Only one study (Ziv and Zitter, 1992), where tests were performed with cotyledons, was found in the literature (reliability 2, as the test is scientifically relevant). NOEC = 5000 mg (NH4HCO3)/L. CL100 = 50000 mg (NH4HCO3)/L (OECD SIDS, Ammonium bicarbonate, Draft 2006).

However, in OECD SIDS Ammonium sulphate (2007), terrestrial toxicity has been assessed more intensively. Equally to the assessment approach of the aquatic and sediment compartment, it can be assumed that the principal toxic component of various ammonium salts, such as ammonium sulphate-, chloride or carbonate is ammonia, rather then the corresponding anion. Consequently, this hazard assessment comprises the general topic of ammonia toxicity.

Therefore, data gaps wihin this chapter were filled by read across to similar ammonium salts, such as ammonium sulphate and ammonium chloride. Effect values as presented, however, are related to ammonium hydrogencarbonate.

The results of terrestrial bacteria- and animal- studies show that the major effect of repeated ammonium sulfate application is a reduction in soil pH, which in agricultural situations is controlled by liming. Observations on plants are mainly attributed to salt effects.

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 241 mg/kg soil (Yeardley et al. 1995, value related to Ammonium hydrogencarbonate. 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 (=847 kg/ha/year Ammonium hydrogencarbonate, 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 (= 98.7 kg/ha Ammonium hydrogencarbonate, calculated from 17.5 kgN/ha, 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 (= 564 kg Ammonium hydrogencarbonate, calculated from 100 kg N, 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 749 mg ammonium bicarbonate / kg soil (calculated from 133 mg N / kg soil). An inhibitory effect was found at 2250 and 2999 mg ammonium bicarbonate / kg soil (calculated from 399 and 532 mg N / kg soil), except for the sandy soil where only 532 mg N / 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 bicarbonate is widely used in various sectors. Besides its application as food additive, and its industrial- and therapeutic use, Ammonium bicarbonate is used as fertilizer. It is well known, that long term exposure of Ammonium sulphate or other ammonia fertilizer significantly reduces soil pH, which in agricultural situations is controlled by liming. Therefore, a direct, uncontrolled exposure of ammonium bicarbonate to the terrestrial compartment does not take place. In addition, due to the rapid transformation of ammonium bicarbonate, an indirect exposure of the terrestrial compartment 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 626 mg / kg Ammonium sulphate = 749 mg / kg Ammonium bicarbonate was used as NOEC.