Slags, phosphorus-manufg.

Endpoint summary

Additional information

The results of the dissolution/transformation test were compared to literature data on the aquatic toxicity for the elements.

Thus ions were selected that are relevant with a view to potential ecotoxicological effects. In addition, Si was included as it is a main constituent.

Element	100 mg/l medium	100 mg/l medium	10 mg/l medium	10 mg/l medium	1 mg/l medium	1 mg/l medium	1 mg/l medium	1 mg/l medium	Toxicity (screening in EPA-ECOTOX)
Test period	7 d	7d	7d	7d	7d	7d	28d	28d
pH	6.5	8.5	6.5	8.5	6.5	8.5	5.5	8.5
Fe, µg/l	<250	<250	<250	<250	<250	<250	<250	<250	EC50 > 5000
Al, µg/l	<50	<50	<50	<50	<50	<50	<50	<50	EC50 > 500
Mn, µg/l	<10	<10	<10	<10	<10	<10	<10	<10	EC50 > 1000
Si, µg/l	1300	710	480	270	<250	<250	<250	<250	EC50 > 100000
F, µg/l	600	300	160	140	<100	<100	<100	<100	EC50 > 10000

Ecotox data for the elements were collected from the EPA-ECOTOX database. The limit listed in the last column of the table is an upper, conservative level covering many tests and species.

It is concluded that the concentration of the elements (ions) that are released from P-slag particles (< 1 mm) in the test do not reach the EC50 values for any of the elements. Thus P-slag will not be acutely toxic at loading rates of 100 mg/l.

The elements solved after 28 days at a loading rate of 1 mg P-slag/l are to be compared to chronic toxicity values (NOEC), that are usually below the acute EC50 by an order of magnitude. Taking this into account it is concluded that the solubility is also sufficiently low as to remain below the NOEC levels.

Due to the poor water solubility aquatic test animals will not be significantly exposed in an aquatic toxicity test. Therefore these tests should be waived.