Registration Dossier

Administrative data

Endpoint:
toxicity to other aquatic vertebrates
Type of information:
other: Review report of experimental data
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The UK Technical Advisory Group (UKTAG) supporting the implementation of the Water Framework Directive (2000/60/EC) is a partnership of UK environmental and conservation agencies. It also includes partners from the Republic of Ireland. This report is the result of research commissioned and funded on behalf of UKTAG by the Scotland & Northern Ireland Forum for Environmental Research (SNIFFER) and the Environment Agency's Science Programme. The PNECs described in this report are based on a technical assessment of the available ecotoxicity data for arsenic, along with any data that relate impacts under field conditions to exposure concentrations. The data have been subjected to rigorous quality assessment such that decisions are based only on scientifically sound data. Following consultation with an independent peer review group, critical data have been identified and assessment factors selected in accordance with the guidance given in Annex V.
Cross-reference
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
grey literature
Title:
Unnamed
Year:
2007

Materials and methods

Principles of method if other than guideline:
The UK Technical Advisory Group (UKTAG) has commissioned a programme of work to derive Environmental Quality Standards (EQSs) for substances falling under Annex VIII of the Water Framework Directive (WFD). This report proposes predicted no-effect concentrations (PNECs) for arsenic using the methodology described in Annex V of the Directive. There are existing EQSs for arsenic, but the method used to derive these is not considered to comply with the requirements of Annex V and so is unsuitable for deriving Annex VIII EQSs.
The PNECs described in this report are based on a technical assessment of the available ecotoxicity data for arsenic, along with any data that relate impacts under field conditions to exposure concentrations. The data have been subjected to rigorous quality assessment such that decisions are based only on scientifically sound data. Following consultation with an independent peer review group, critical data have been identified and assessment factors selected in accordance with the guidance given in Annex V.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
See in Results and Discussion

Sampling and analysis

Details on sampling:
See in Results and Discussion

Test organisms

Test organisms (species):
other: See in Results and Discussion

Study design

Test type:
other: See in Results and Discussion
Remarks on exposure duration:
See in Results and Discussion

Results and discussion

Effect concentrationsopen allclose all
Duration:
6 d
Dose descriptor:
LOEC
Effect conc.:
13 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: As(V) compound not specified
Basis for effect:
other: growth inhibition
Remarks on result:
other: Algae = Diatom (Skeletonema costatum). Measured concentrations. Klimisch = 2
Duration:
17 wk
Dose descriptor:
NOEC
Effect conc.:
> 20 - < 50 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Remarks:
Arsenate (as Na 2 HAsO 4 )
Basis for effect:
other: Growth/survival
Remarks on result:
other: Brown alga (Fucus serratus). Measured concentrations. Klimisch 1.
Duration:
28 d
Dose descriptor:
other: NOEC unbounded
Effect conc.:
25 µg/L
Nominal / measured:
nominal
Conc. based on:
other: Sodium arsenate
Basis for effect:
other: growth
Remarks on result:
other: Daggerblade grass shrimp (Palaemonetes pugio). Measured concentrations. Klimisch 2
Duration:
15 d
Dose descriptor:
other: Effect: significant increase in juveniles mortality
Effect conc.:
100 µg/L
Nominal / measured:
not specified
Conc. based on:
other: AS (V)
Basis for effect:
mortality
Remarks on result:
other: Copepod (Eurytemora affinis)
Duration:
13 d
Dose descriptor:
EC50
Effect conc.:
1 400 µg/L
Nominal / measured:
nominal
Conc. based on:
other: AsHNa 2 O 4 (V)
Basis for effect:
other: reproduction
Remarks on result:
other: Harpacticoid copepod ( Nitocra spinipes ). No measured concentrations.
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
10 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: AsH 3 O 4 (V)
Basis for effect:
mortality
Remarks on result:
other: Pacific oyster (Crassostrea gigas). Klimisch 3
Duration:
10 d
Dose descriptor:
NOEC
Effect conc.:
2 650 µg/L
Nominal / measured:
nominal
Conc. based on:
other: Arsenite oxide
Basis for effect:
mortality
Remarks on result:
other: Fish, Pink salmon (Oncorhynchus gorbuscha). No Measured concentrations. Klimisch 2

Any other information on results incl. tables

The lowest reliable chronic data in the saltwater database are for the marine diatom Skeletonema costatum, with LOECs of 13 µg/l for As (V) (it was not possible to derive a NOEC or an LC10 from the data reported in the study references). This study was based on measured exposure concentrations in a static system and was regarded as suitable for PNEC derivation. In addition, data for the macroalga Fucus serratus indicate a growth and mortality related NOEC of 20 µg/l As(V) . This datapoint was generated in a flow-through study with measured exposure concentrations and is reliable for PNEC derivation.

Reliable chronic effects values for marine invertebrates are much higher than those reported for algae. However, there is one 48-hour test on sea urchin embryo development that may be considered as an early life stage (ELS) test rather than anacute test; this reported a LOEC of 11 µg l -1 As(V) for development of embryos of the sea urchin Strongylocentrosus purpuratus. On the basis of the data reported, it was possible to derive an EC10 of 6 µg/l and an EC50 of 15 µg/l. This study was based on nominal concentrations, but was regarded as valid for PNEC derivation because in

studies where nominal concentrations of arsenic have been compared with measured concentrations they have been found to be almost identical .

Only limited fish data were available.

For some acute effects, the lowest reported values are in the same range as the lowest chronic data, i.e. the 120-hour EC50 for the alga Skeletonema costatum of 9 µg/l As(V) and the 96-hour LC50 of the crustacean Tigriopus brevicornis of 11 µg/l As(V).

Following the given in the TGD for marine risk assessment, this situation (in which the lowest acute effect values are as low as the lowest chronic values) requires the use of an assessment factor of 1,000 on the lowest acute value. However, as it is not possible to gain access to the background documentation for the Skeletonema acute EC50 of 9 µg/l in the original reference, the validity of this test result is not

assignable. The other references have been evaluated and are considered reliable.

Based on the other data, the saltwater acute to chronic ratios for arsenic appear to be low, suggesting that only a small assessment factor would be required to extrapolate from an effects concentration to a no-effect concentration. In addition, long-term NOECs for more than three marine species representing three trophic levels (i.e. algae, crustaceans, echinoderms and molluscs) plus acute data for a further marine

group (annelids) are available. Consequently, it is recommended that the PNEC add,saltwater_lt is based on the lowest available EC10 of 6 µg/l reported by Garman et al. and an assessment factor of 10:

PNEC add,saltwater_lt = 6 µg/l /AF (10) = 0.6 µg/l arsenic (dissolved)

Applicant's summary and conclusion

Validity criteria fulfilled:
not applicable
Conclusions:
Given the availability of data for other trophic levels, an assessment factor of 10 applied to this EC10 is recommended, leading to a PNEC saltwater_long-term of 0.6 µg/l arsenic (dissolved).
Executive summary:

Long-term PNEC for saltwaters

Similar toxicities (expressed as LOECs) are seen in studies with the marine diatom, Skeletonema costatum, for As(III) and As(V) (10 and 13 µg/l , respectively). Although most invertebrates are less sensitive, embryo development in the sea urchin Strongylocentrosus purpuratus was impaired after 48-hour exposure to As(V). This gave rise to a LOEC of 11 µg/l, but it was not possible to estimate a NOEC from this study. Subsequent re-analysis of the study data gave an EC50 of 15 µg/l and an EC10 (considered equivalent to a NOEC) of 6 µg/l. Given the availability of data for other trophic levels, an assessment factor of 10 applied to this EC10 is recommended, leading to a PNEC saltwater_long-term of 0.6 µg/l arsenic (dissolved).