Ammonia, anhydrous

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to terrestrial plants: short-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: review article

Principles of method if other than guideline:

no details provided

GLP compliance:

not specified

Species:

other: various

Dose descriptor:

NOEC

Effect conc.:

>= 0.1 - <= 0.5 other: mmol/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Remarks:

NH4+

Basis for effect:

growth

Remarks on result:

other: test duration not applicable since this is information from a review article. This NOEC is provided for sensitive species (barley).

Details on results:

The reported symptoms of NH4+ toxicity range widely, and generally appear with external NH4+ concentrations above 0.1 to 0.5 mmol/L (Schenk and Wehrmann 1979, Peckol and Rivers 1995, van Katwijk et al. 1997). Figure 1 shows, in the sensitive species barley, two of the most dramatic of these symptoms: the chlorosis of leaves, and the overall suppression of growth (Kirkby and Mengel 1967, Kirkby 1968, Gigon and Rorison 1972, Breteler 1973, Holldampf and Barker 1993, Gerendas et al. 1997).

The concentration of 0.1 mmol NH4/L corresponds to 0.1 mmol NH3/L (worst case if NH3 is considered to be the toxic component) which is equivalent to 1.7031 mg/L.

Conversion of the information: 0.1 mmol/L to mg NH3/kg dw
lowest NOEC reported			0.1	mmol/L
mol weight NH3			17.031	g/mol
lowest NOEC reported			1.7031	mg NH3/L
CALCULATION OF THE WATER CONTENT OF TYPICAL SOIL
The conversion from wet soil to dry soil was performed according of the Technical Guidance on Risk Assessment Part II published by the European Chemicals Bureau 2003. The calculation was performed using equation 82b (page 132) with the supporting information from Table 5 (page 43) and equation 18 (page 44). A conversion a factor of 1.13 kg wet soil/kg dry soil was calculated.			1.13	kg wet soil/kg dry soil
´=> 1 kg dry soil will take up 0.13 L = 130 mL water on average.
1 mL solution will contain			0.0017031	mg NH3
130 mL will contain			0.221403	mg NH3
When dryed, the water will be removed and hence the content of the 130 mL will be present in the dry soil.
Final result:			0.221	mg NH3 / kg dw

Conclusions:

The lowest NOEC for plants (barley) reported is 0.1 mmol/L which corresponds to 0.221 mg NH3/kg dw.

Executive summary:

The lowest NOEC for plants (barley) reported is 0.1 mmol/L as determined in a soil-free system which corresponds to 0.221 mg NH3/kg dw.

Reference 2

Endpoint:

toxicity to terrestrial plants, other

Type of information:

other: Experience; Ammonia is used as a component of fertilisers, therefore toxicity to terrestrial plants is not predicted.

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Experience

Principles of method if other than guideline:

Ammonia is used as a component of fertilisers, therefore toxicity to terrestrial plants is not predicted.

GLP compliance:

no

Remarks on result:

not measured/tested

Details on results:

Ammonia is used as a component of fertilisers. Therefore, toxicity to terrestrial plants is not predicted at environmentally relevant concentrations.

Nitrogen sources are needed for all plants. Excess ammonium will rather result in a shift in plant composition due to competition rather than due to toxic effects. Shift in plant species composition is not an ecotoxicological endpoint and is hence not relevant for the assessment.

Description of key information

Ammonia is used as a component of fertilisers. Nevertheless, ammonia (non-point-source) can cause toxic effects on sensitive plants. The lowest NOEC for plants (barley) reported is 0.1 mmol/L as determined in a soil-free system which corresponds to 0.221 mg NH3/kg dw.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for terrestrial plants:

0.221 mg/kg soil dw

Additional information

Ammonia is used as a component of fertilisers. Nevertheless, ammonia (non-point-source) can cause toxic effects on sensitive plants. The lowest NOEC for plants (barley and tomatoes) reported is 0.1 mmol/L as determined in a soil-free system which corresponds to 0.221 mg NH3/kg dw assuming an average water holding capacity of 13% (typically 5- 40%).

Exposure to gasous ammonia might be of relevance for terrestrial plants as well.