Licheninase

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

5.2 µg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

52 µg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.52 µg/L

Assessment factor:

10 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

65 000 µg/L

Assessment factor:

1

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

no exposure of sediment expected

Sediment (marine water)

Hazard assessment conclusion:

no exposure of sediment expected

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

2.8 µg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Licheninase was tested for acute toxicity to crustacean and algae. These were however supporting studies. Other cross-reference studies were included with alpha-amylase (IUB 3.2.1.1), belonging to the same class of enzymes.

For crustacean Daphnia magna: Under the conditions of the test, licheninase, batch PPB41588 was not found to be toxic to Daphnia magna at a nominal concentration up to 100 mg TOS/L after 48h exposure. Thus, no 48h EC50 could be calculated and must be >100 mg TOS/L (>6.42 mg/L aep). The 48h EC50 value for alpha-amylase with Daphnia magna was 2000 mg test material/L corresponding to 212 mg active enzyme protein/L.

For algae: Licheninase batch PPB41588 was not toxic to Pseudokirchneriella subcapitata as no significant growth inhibition was observed up to a concentration of 100 mg TOS/L. Thus, no 72h ErC50 could be calculated, and should be >100 mg TOS/L (>6.42 mg/L aep). Alpha-amylase is inhibitory to the growth of Desmodesmus subspicatus at concentrations in excess of 12.5 mg/L corresponding to 1.3 mg active enzyme protein (aep)/mL. The EbC50 (72h) value is 24 mg/L and the ErC50 (24-72h) is 49 mg/L corresponding to 2.5 and 5.2 mg aep/L, respectively.

Inhibition control carried out with non-proteolytic enzymes in the test of ready biodegradability showed no inhibition of the activated sludge inoculum at an enzyme concentration above the expected levels in inlet to sewage treatment plants (STPs). Monitoring of enzymes in the inlet to municipal STPs (in Denmark) resulted in concentrations of less than 2 µg aep/L which are below the initial concentration used in tests for ready biodegradability, where no inhibitory effects were observed. It is concluded that a study on activated sludge respiration inhibition does not need to be conducted. Therefore, licheninase is not considered to be toxic to microorganisms.

The EC50 for algae was 5.2 mg active enzyme protein/L was used for PNEC derivation and the assessment factors 1000 and 10000 were applied for fresh and marine water, respectively.

The PNEC value for STP is based on actual measurements of enzyme concentration in STP connected to manufacturing site. Up to 65000 µg active enzyme protein were detected in STP connected to manufacturing site and since there was no negative impact observed, this concentration is the estimated PNEC value for STP.

PNEC values for sediment exposure have not been derived because licheninase is readily biodegradable, highly water soluble and has a very low potential for adsorption to sediments. Exposure of the sediment to toxicologically significant concentrations of the test substance is thus not expected.

As no soil ecotoxicity data are available for licheninase, the PNEC for soil is based on the PNEC for surface water using the equilibrium partitioning method. PNEC soil was estimated to 2.5 µg active enzyme protein/kg soil ww.

Licheninase is not expected to cause any significant secondary poisoning as it is ready biodegradable and has no bioaccumulation potential. Furthermore, as licheninase is a protein it is expected to be degraded in the gastrointestinal tract. Thus, PNEC oral is not relevant.

Conclusion on classification

Based on the aquatic toxicity studies and the ready biodegradation of the enzyme, licheninase is not classified.