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The environmental profile of burnt oil shale has been well defined. Short-term tests with species of three trophic levels as well as long term data for daphnia and algae and data for activated sludge are available for water accommodated fractions of the substance. Oil shale thermal processing residue proved to be harmful to green algae (Pseudokirchneriella subcapitata) as evidenced by an EL50 (72 h) value for the growth rate of 82.7 mg/L (OECD 201).

Short term effects of the substance towards fish and daphnia were found to be in the same range providing NOEL values of greater than 100 mg/L. Additionally, the long term toxicity tests to aquatic invertebrates indicated that oil shale thermal processing residue did not affect the growth or reproduction of Daphnia magna when exposed for 21 days to a WAF prepared at a loading rate of 1 mg/L (NOELR; OECD 211). Algae indicated to be in the same range and revealed in a NOELR (72 h) of 3.2 mg/L for growth rate (OECD 201).

The 3-h NOEC of the test item for respiratory inhibition of activated sludge fed with synthetic sewage was > 1000 mg/L (OECD 209). Oil shale is not harmful to activated sludge microorganisms and an inhibition of the degradation activity of sludge is not to be expected.

The heavy metal content has no influence on the toxic effects of the test substance on aquatic organisms. Measured data from a leaching test shows that the bioavailability of the heavy metals is low. Measured leaching data for oil shale were reported in the PC chapter 4.23 of IUCLID dataset and are summarised below.

The concentrations of all elements measured were found in the range of µg/L or below detection limit (see Table 27).

 Table 27: Concentration of the water soluble components in the WAF´s [µg/L]

 

Parameter

Leachate [µg/l]

As

<5

Pb

11

Cd

<0.5

Cr (total)

86

Cu

<5

Ni

<5

Hg

<0.2

Tl

<1

Zn

<30