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Ecotoxicological information

Toxicity to aquatic plants other than algae

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Reference
Endpoint:
toxicity to aquatic plants other than algae
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
supporting study
Study period:
06-09-1996
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
No guideline followed, however, study is quite complete, no analysis was done. PH was not fixed and varied between 8.0 and 3.9, this is just the pH range in which the AL speciation varies widely, and because no analysis was done it is unknown whether the bioavailable fraction is big enough to cause effects with respect to nominal plays a role in the endpoints. Also the fact that no information on substance identity was provided does not add reliability. This makes the result not usable as keystudy
Qualifier:
no guideline followed
GLP compliance:
not specified
Analytical monitoring:
no
Details on test solutions:
All replicates of each treatment received concentrations
of 0.0, 10.0, or 20.0 mg/l Al with or without humic substances.
Aluminum was supplied in the form of AlK (SO4)2 * 12H2O which was added to the growth media to obtain the
above concentrations.
Test organisms (species):
other: Salvina minima
Details on test organisms:
Salvinia plants with a total of 30 leaves were placed in each
of 12 Erlenmeyer flasks representing each treatment. Each
flask contained 125 ml of modified Hoagland solution (Hoagland and Arnon 1938), diluted 1:40 (Sela et al. 1989)
at pH 3.9.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
14 d
pH:
3.9-5.0
Nominal and measured concentrations:
nominal: 10, 20 mg/L
Details on test conditions:
The plants were placed in a growth
chamber at 25C, 220 μmol m-2s-1 photon flux density, and a
14-h photoperiod.
Salvinia was grown under the above conditions for 14 days
with the growth solution being changed after seven days to
minimize algae contamination. At the end of 14 days, six randomly
selected samples of 12 total samples of each treatment
were used for dry weight and carbohydrate determination.
The other samples were used to test for chlorophyll a and b,
carotenoid and anthocyanin concentrations.
Reference substance (positive control):
no
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
19 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
The presence of 10.0 and 20.0 mg/l Al without humic substances
in the growth media resulted in a reduction in salvinia
growth at both the corrected and the uncorrected pH
treatments (Table 1). This reduction in the plants growth
was even greater with those grown at 20.0 mg/l in comparison
to those grown at 10.0 mg/l. The presence of Al might
cause a decrease in the uptake and transport of some of the
essential plant nutrients. Maessen et al. (1992) reported that
elevated levels of Al inhibited the uptake of Ca, Mg, Fe, Mn,
and Zn by competing for binding sites. Furthermore, Al was
shown to interfere with mitosis and cell elongation in the
root system of Allium ursinum L. (Andersson 1993)
Reported statistics and error estimates:
EC50 was calculated by the reviewer based on data in the article and single variable lineair regression (r^2 was 0.99 and p=0.012)
Validity criteria fulfilled:
not applicable
Conclusions:
The EC50 was determined to be 19 mg/L AlK(SO4)*12H2O nominal. The article describes the method short but quite clear.
Executive summary:

This study was performed with aluminium potassium sulphate. Salvinia increased the pH of the growth media within two days to near neutral pH in the absence of Al with and without humic substances. In most cases, Al in the absence of humic substances reduced salvinia growth, chlorophyll a and b concentrations, and carotenoid concentrations. Reductions were greater with increasing concentrations of Al and humic substances alleviated some of the toxic effects of Al. Also, corrected treatments (pH 3.9) influenced an increase in the above parameters for most treatments compared to uncorrected treatments (pH varied according to the treatment). Anthocyanin concentrations of salvinia increased in treatments receiving Al. The accumulation of soluble sugars, starch, and total nonstructural carbohydrates (TNC) increased in the presence of 20.0 mg/l Al without humic substances and decreased in treatments receiving humic substances. The EC50 was determined by the reviewer to be 19 mg/L nomimal.

Description of key information

No guideline followed, supporting study, validity 4, (Gardner and Al-Hamdani 1997, semi-static):

14 d - EC50 (growth rate) = 19 mg/L (based on nominal concentrations)

Key value for chemical safety assessment

EC50 for freshwater plants:
19 mg/L

Additional information

One read-across study on aluminium potassium sulphate is available.

This study was performed with aluminium potassium sulphate. Salvinia increased the pH of the growth media within two days to near neutral pH in the absence of Al with and without humic substances. In most cases, Al in the absence of humic substances reduced salvinia growth, chlorophyll a and b concentrations, and carotenoid concentrations. Reductions were greater with increasing concentrations of Al and humic substances alleviated some of the toxic effects of Al. Also, corrected treatments (pH 3.9) influenced an increase in the above parameters for most treatments compared to uncorrected treatments (pH varied according to the treatment). Anthocyanin concentrations of salvinia increased in treatments receiving Al. The accumulation of soluble sugars, starch, and total nonstructural carbohydrates (TNC) increased in the presence of 20.0 mg/l Al without humic substances and decreased in treatments receiving humic substances. The EC50 was determined by the reviewer to be 19 mg/L nomimal.