Dolomite (CaMg(CO3)2), calcined

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.465 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.465 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.303 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

2.85 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

insufficient hazard data available (further information necessary)

Sediment (marine water)

Hazard assessment conclusion:

insufficient hazard data available (further information necessary)

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

1 023.1 mg/kg soil dw

Assessment factor:

1

Extrapolation method:

assessment factor

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

PNECaqua (fresh water), PNEC marine

The PNECaqua (freshwater) and the PNEC marine for dolomite calcined are calculated from these values for calcium dihydroxide, based on the read-across rationale mentioned in previous sections. Hereafter, an explanation is given with regard to the lowering of the assessment factor for calculating PNECaqua (freshawater) and PNEC marine for calcium dihydroxide, which consequently affects these values for dolomite calcined.

According to the REACH guidelines an assessment factor of 1000 should be applied to the lowest value, being 49.1 mg Ca(OH)2/L for freshwater species Daphnia magna (48h-EC50) and 32 mg Ca(OH)2/L for marine species Crangon septemspinosa (14d-NOEC). However, testing immediately after application of lime substances yields an overestimate of the exposure and hence potentially also results in an overestimation of the effects compared to field conditions. Depending on the properties of the test medium, calcium dihydroxide will be strongly neutralised in the initial period after application. Moreover, test media in standard laboratory toxicity tests are expected to have lower buffer capacity compared to natural waters (hardness, presence of particles and colloids). Therefore, a decreased assessment factor is applied. Summary of variation/uncertainty to be taken into account:

* intra- and inter-laboratory variation of toxicity data: no data, but considered of minor importance compared to variation across species

* intra- and inter-species variations (biological variance): needs to be corrected for

* short-term to long-term toxicity extrapolation: needs to be corrected for

* laboratory data to field impact extrapolation: because of the overestimation of exposure during toxicity tests, this may decrease the assessment factor

Because of the conservative nature of laboratory tests where test species are exposed to lime substances without equilibration of the lime in the test medium, the standard assessment factor from the REACH guidance was decreased by a factor 10. An assessment factor of 100 to be applied on the lowest effect data currently available, results in a PNECaqua, fresh water of 0.49 mg Ca(OH)2/L and a PNECaqua, marine of 0.32 mg Ca(OH)2/L. This approach also agrees with the note a from Table R.10-4 from the REACH guidance.

PNEC terrestrial

The PNECterrestrial for dolomite calcined is calculated from this value for calcium dihydroxide, based on the read-across rationale mentioned in previous sections. Hereafter, an explanation is given with regard to the lowering of the assessment factor for calculating PNECterrestrial for calcium dihydroxide, which consequently affects these values for dolomite calcined.

According to the REACH guidelines an assessment factor of 10 should be applied to the lowest NOEC value, being 1080 mg Ca(OH)2/kg dw for growth (shoot fresh weight) of Brassica napus. However, testing immediately after application of lime substances may yield an overestimate of the exposure and hence potentially overestimates the effects. The soils used for ecotoxicity testing have all a relative low organic matter and clay content and can therefore be expected to have limited buffer capacity. Therefore, a decreased assessment factor is applied.

The availability of multiple data (for 6 species) for the most sensitive taxonomic group (plants) can also justify decrease of the assessment factor. Summary of variation/uncertainty to be taken into account:

* intra- and inter-laboratory variation of toxicity data: no data, but considered of minor importance compared to variation across species

* intra- and inter-species variations (biological variance): needs to be corrected for, however multiple data available for most sensitive taxonomic group

* short-term to long-term toxicity extrapolation: not applicable (only chronic data available)

* laboratory data to field impact extrapolation: because of the overestimation of exposure during toxicity tests, this may decrease the assessment factor

Because of the conservative nature of laboratory tests where test species are exposed to lime substances without equilibration of the lime in the test medium and the availability of multiple data for the most sensitive taxonomic group, the standard AF from the REACH guidance was decreased by a factor 10. As such, an assessment factor of 1 to be applied on the lowest NOEC available, results in a PNECsoil of 1080 mg Ca(OH)2/kg.