Nitrapyrin

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.01 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.017 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.001 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

1.127 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.512 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.051 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.178 mg/kg soil dw

Assessment factor:

10

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

3.33 mg/kg food

Assessment factor:

30

Conclusion on classification

Aquatic

Short-term L(E)C50 results are available for each of the three trophic levels. In addition long term data is available for all three trophic levels (fish, daphnia and algae).

Fish: Short-term toxicity was investigated in several fish studies (data available from 1978 to 2014). The LC50 (96h) values range from 3.4 mg/L (bluegill sunfish) to 9.1 mg/L (rainbow trout).

One long term toxicity study is available according to OECD 210 giving a NOEC value of 1.38 mg/L for fathead minnow.

Invertebrates: OECD TG 202 acute toxicity tests to Daphnia magna were performed. The EC50 (48h) are between 2.2 mg/L and 5.78 mg/L. One long term daphnia reproduction study (OECD 211) is available with a NOEC (reproduction) of 0.103 mg/L. This endpoint was used to calculate the PNECaquatic. For further details see the PNEC section above.

Algae/Aquatic Plants: Three algal growth inhibition tests and one study with Lemna gibba are available. Exposure of Selenastrum capricornutum gave the lowest ErC50 (72h) value of 1.7 mg/L. The lowest No Observed Effect Concentration was determined for Navicula pellicula of 0.36 mg/L.

Sediment

No experimental data on sediment toxicity are available. Therefore the PNEC sediment was calculated by the equilibrium partitioning method. For further details see the PNEC section above.

Terrestrial

For the terrestrial environment long term toxicity data is available non-target plant and earthworms. A 56-day reproduction study with Eisenia fetida resulted in a NOEC of 3.91 mg/kg dwt (normalised to standard organic matter content of 3.4%) and a NOEC of 1.78 mg/kg (NOEC of 1000 g a.s./ha converted to a NOEC of 1.33 mg/kg dwt at 5 cm soil depth and then converted to standard organic matter content of 3.4%) was the result of a 21-day seedling emergence/growth study.

Due to the fact that nitrapyrin is applied to soil as fertilizer based on its nitrification inhibitor properties several non-GLP/non-standard protocol studies and publications on soil organism (one short-term earthworm and several on plants and soil micro-organism) are available. Soil-micro-organisms can be considered as the most sensitive species based on the nitrification inhibition effect. Roberts et al. (2003 assessed the toxic effects of nitrapyrin according to the OECD TG 216. An EC50 for nitrapyrin was calculated of 3.1 mg/kg dwt soil. Although this represents the most sensitive species and lowest endpoint, it was decided to not use it for the PNEC derivation: The intended use of nitrapyrin is to inhibit nitrification and therefore the PNEC should not be based on effects on soil nitrification as this is the desired effect of the product in the application area. Therefore it is suggested to base the PNEC on nitrapyrin's toxicity against earthworms and non-target plants, where the latter was considered as the most sensitive species and used to calculate the PNECsoil.

STP

An OECD TG 209 respiration inhibition test was performed giving an EC50 value of 112.7 mg/L. This value was used for deriving a PNECstp. For further details see the PNEC section above.