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As (residues), cenospheres (CAS 93924-19-7) are hollow ceramic microspheres of alumosilicates (SiO2+Al2O3) which are also produced during the generation of Ashes (residues), coal. Cenospheres are inert, hollow balls of sand-like material. Cenospheres are not harmful to the environment and if released to water the gas bubbles cause the cenospheres to be so lightweight that they float on water. The most composition related ash (residues), coal was used as read across for cenospheres.

Read across of these ashes are justified as they are all are characterised by a very similar composition on the one hand and the same production process on the other hand. Furthermore, the related ash (residues), coal can be seen as a worst case approach due to the characteristics of the substances. The ashes are hardly soluble but partly available for aquatic organisms in comparison to the cenospheres; they float on water and are not bioavailable to aquatic organisms.

The environmental profile of ash (residues), coal has been well defined. No toxicity was observed in any of the tests with the tested ash, which is composition related to the cenospheres. The NOEL of green algae is greater than 100 mg/L. 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 the tested ash also did not affect reproduction or survival ofDaphnia magnaat a WAF prepared at a loading rate of 100 mg/L after 21 days of exposure.

The heavy metal content has no influence of the toxic effects of the test substance on aquatic organisms.Measured leaching data for cenospheres were reported in the PC chapter 4.23 of IUCLID dataset and summarised below:

Scanned metalsfrom different samples (different sources) of cenospheres:

 

Element

Concentration

Concentration

 

[mg/L]

[mg/L]

Li

< 0.01

< 0.01

Be

< 0.01

0.04

B

0.05

0.07

Na

0.34

0.8

Mg

0.59

0.77

K

2.15

1.22

Ca

1.65

1.22

Cr

< 0.01

< 0.01

Mn

< 0.01

< 0.01

Fe

0.39

0.07

Co

< 0.01

< 0.01

Ni

< 0.01

< 0.01

Cu

< 0.01

< 0.01

Zn

< 0.01

< 0.01

Ga

< 0.01

< 0.01

Se

< 0.01

< 0.01

Sr

0.15

0.06

Cd

< 0.01

< 0.01

Te

< 0.01

< 0.01

Ba

0.06

0.04

Tl

< 0.01

< 0.01

Pb

< 0.01

< 0.01

Bi

< 0.01

< 0.01

 

Element

 

Leachate Metals Concentration - Parts Per Million (mg/L) –STLC-leachate

 

Leachate Metals Concentration - Parts Per Million (mg/L) –TCLP-leachate

Antimony

ND

0.001

Arsenic

0.21

0.055

Barium

2.3

0.517

Beryllium

ND

ND

Cadmium

ND

ND

Chromium (CrVI+ CrIII)

0.12

0.005

Cobalt

0.03

0.004

Copper

0.11

0.007

Lead

0.06

ND

Mercury

ND

ND

Molybdenum

0.08

0.023

Nickel

0.08

0.018

Selenium

ND

ND

Silver

ND

ND

Thallium

ND

ND

Vanadium

0.38

0.043

Zinc

0.35

0.088

ND: not detected

 

Element

Leachate Metals Concentration - Parts Per Million (mg/L) –STLC-leachate

 

Leachate Metals Concentration - Parts Per Million (mg/L) –TCLP-leachate

Antimony

0.03

0.007

Arsenic

0.28

0.042

Barium

2.28

0.513

Beryllium

ND

ND

Cadmium

ND

ND

Chromium (CrVI+ CrIII)

0.14

0.011

Cobalt

0.02

0.004

Copper

0.25

0.028

Lead

0.14

0.004

Mercury

ND

ND

Molybdenum

0.07

0.018

Nickel

0.05

0.011

Selenium

0.25

0.135

Silver

ND

ND

Thallium

ND

ND

Vanadium

0.84

0.115

Zinc

0.29

0.053

ND: not detected

The concentrations of elements in the test were found to be very low. Most elements, which are known to have negative effects on health and environment were not detected or found in very low concentrations.