Sodium permanganate

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

See the read-across report attached in Section 13

Reason / purpose for cross-reference:

read-across source

Duration:

14 d

Dose descriptor:

other: Effect on growth

Effect conc.:

10 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Duration:

20 d

Dose descriptor:

NOEC

Effect conc.:

20 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Settlement

Reference 2

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

See the read-across report attached in Section 13.

Qualifier:

no guideline followed

Principles of method if other than guideline:

The effects of up to eight elements, including manganese, on C.gigas larval settlement and spat growth were investigated using a single larval culture for each comparative test. The metal concentrations were chosen in the range to cause sub-lethal rather than lethal effects. Lethal concentrations (LC50; causing 50% mortality in a specified period) were not determined except where they occurred in the selected concentration range. Experimental observations included growth and behaviour in addition to mortality.

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 10 and 20 µg/l of Mn2+.
- Sampling method: Samples from each treatment were collected at selected intervals and behaviour and structure examined.

Vehicle:

no

Details on test solutions:

Treatments, 10 and 20 µg/l of Mn2+ prepared in triplicate, were continued throughout the 20-day experiment.

Test organisms (species):

other aquatic mollusc: Crassostrea gigas

Details on test organisms:

C. gigas larvae and spat were obtained from hatchery stock cultures. Hatchery procedure included the sieving of larvae and spat through nylon screens of selected mesh sizes. Thus the range of individual sizes was restricted at the beginning of each experiment. Samples from each treatment were collected at selected intervals and behaviour and structure examined. Measurements made included width across the value for larvae and length of spat.

Larvae were encouraged to settle on discs of black PVC placed in the bottom of each beaker. These discs were slightly arched so that both upper and lower surfaces were available for settlement. The number of larvae settling on the black discs in each beaker was counted but spat were not scraped off. Those which settled in the presence of metals were grown for an additional period in clean water.

Small cultchless-spat were suspended on a 400 µm nylon mesh; older spat were suspended on screens of larger mesh size. Samples were examined daily and measured at intervals during both the treatment and the succeeding period in clean sea water. Gaping individuals were removed. Spat in the size range tested may have been dead for up to two days before the shells gaped.

Test type:

static

Water media type:

saltwater

Total exposure duration:

20 d

Nominal and measured concentrations:

10 and 20 µg/l of Mn2+

Details on test conditions:

TEST MEDIUM
The experimental solutions were prepared to contain a combination of the flagellates Monochrysis lutherii, Isochrysis galbana, Chaetoceros calcitrans and Tetraselmis chui to give a final combined concentration of 150 cells/µl.
The algal mix was supplied daily from the hatchery.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Growth and settlement.

Duration:

14 d

Dose descriptor:

other: effect on growth

Effect conc.:

10 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

Duration:

20 d

Dose descriptor:

NOEC

Effect conc.:

20 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Settlement

Details on results:

Settlement was plotted on a daily basis and settlement patterns for zinc, cadmium and copper illustrated three possible effects:

a) Maximum settlement delayed with respect to that in the control (zinc, also lead).

b) Maximum settlement coincident with that in the control (cadmium, also MANGANESE, nickel and chromium).

c) Maximum settlement occurring earlier than that in the control (20 µg/l copper, also 20 µg/l cobalt).

The only element which appeared to promote metamorphosis and settlement was copper, for which 80 and 95% of the larvae settled in the 10 and 20 µg/l treatments respectively, compared with 72% in the controls and 68% in the presence of manganese. All other elements tested caused a significant decrease in the total numbers of larvae settling (between 35-45%).

The effects of manganese on 51-day old cultchless C. gigas spat were recorded (see table 1).
All the metals which were tested caused a reduction in growth during the 14-day treatment period. However, recovery was such that individuals in all treatments were approximately the same size as those in the controls after a further 14 days in clean sea water.

Table 1:

Growth and recovery of 51 -day old cultchless spat (mean length 3.7 mm) exposed to eight elements (results as mean spat length (mm)).

Treatment	After 14 days treatment	After further 14 days in clean water
Control	6.3	8.2
Control	6.2	8.2
Mn 10 µg/l	5.2	7.9
Mn 20 µg/l	5.4	7.6

Validity criteria fulfilled:

not specified

Conclusions:

Mn2+was determined not to be detrimental to C. gigas settlement success. Manganese caused a reduction in spat growth during exposure in the metal exposure in the 10-20 μg/l range.
Under the conditions of the study the NOEC was 20 μg/l.

Executive summary:

The effects of manganese on C.gigas larval settlement and spat growth were investigated using a single larval culture for each comparative test. The metal concentrations were chosen in the range to cause sub-lethal rather than lethal effects. Lethal concentrations (LC50; causing 50 % mortality in a specified period) were not determined except where they occurred in the selected concentration range. Experimental observations included growth and behaviour in addition to mortality.

Under the conditions of the study the NOEC was 20 μg/l.

Description of key information

Under the conditions of the study the NOEC for the read across source substance was 20 μg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

20 µg/L

Additional information

The effects of manganese on C.gigas larval settlement and spat growth were investigated using a single larval culture for each comparative test. The metal concentrations were chosen in the range to cause sub-lethal rather than lethal effects. Lethal concentrations (LC50; causing 50 % mortality in a specified period) were not determined except where they occurred in the selected concentration range. Experimental observations included growth and behaviour in addition to mortality. The study was awarded a reliability score of 2 in accordance with the criteria set forth by Klimisch et al. (1997).

Under the conditions of the study the NOEC was 20 μg/L.