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Ecotoxicological information

Additional ecotoxological information

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Endpoint:
additional ecotoxicological information
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
Published, investigative non-guideline, non-GLP study.
Cross-referenceopen allclose all
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
read-across source
Reference
Endpoint:
additional ecotoxicological information
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
Published, investigative non-guideline, non-GLP study.
Justification for type of information:
Sulphur trioxide readily reacts with water to form sulphuric acid. The reaction is instantaneous, to the extent that SO3 will react with water vapour in the atmosphere to form fumes of sulphuric acid. This reaction forms the basis of the manufacturing process of H2SO4. The read-across hypothesis is therefore that SO3 will instantaneously transform into H2SO4 upon contact with water (i.e. in aquatic ecotoxicology tests), thus any observed effects will be directly attributable to sulphuric acid. It is therefore justifiable to derive hazard conclusions from sulphuric acid data, with regard to ecotoxicological endpoints.
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
read-across source
Qualifier:
no guideline available
Principles of method if other than guideline:
The pH of Lake 223, Ontario, Canada, was lowered from 6.7 in 1974 to 5.1 by 1981. Samples of cladocera were taken each year and the species composition and overall biomass were monitored.
GLP compliance:
no
Type of study / information:
Published paper describing experimentally derived results.
Specific details on test material used for the study:
Available study data for sulphuric acid is being used for read-across to the target substance, sulphur trioxide.

Total zooplankton biomass was not reduced by acidification and may have increased in 1980. Prior to acidification, mean ice-free season biomass was 269 mg/m2, during 1977 to 1980 it was 318, 218, 204 and 401 mg/m2 respectively. During 1981 to 1984 biomass was 279, 236 and 247 mg/m2. Although total biomass did not greatly change with acidification, total biomass of cladocerans increased during1918 to 1983. This occurred at the expense of calanoid copepods and to a lesser extent cyclopoid copepods. In 1974 adults of D. minutus were present at a biomass of 33 mg/m2. During 1981 to 1983 their biomass was 26, 17 and 24 mg/m2. Cladocerans also exhibited marked changes in species composition. The community in 1974 at pH 6.7 was dominated by Daphnia galeata mendotae with Diaphanosoma birgeiand Bosmina longirostris also present, Holopedium gibberum was rare. At pH 5.1 Daphnia catawba, H. gibberum and B. longirostris were all abundant. D. birgei and D. g. mendotaehad dissappeared or become rare. D. catawba recorded for the first time in 1980 was usually the sole daphnid at pH 5.1, it replaced D. g.mendotaealmost entirely during the 1918 to 1983 period. Chaoborus has been incidentally samples along with the zooplankton, there is no evidence it changed markedly in abundance with acidification.

Conclusions:
The reported study is adequate in demonstrating the effects of lowering pH on the compostion and structure on cladocera.
Executive summary:

Data on the toxicity to zooplankton is available for sulphuric acid and is considered suitable for read-across (based on the analogue approach) to the target substance, sulphur trioxide. Sulphur trioxide readily reacts with water to form sulphuric acid. The reaction is instantaneous, to the extent that SO3 will react with water vapour in the atmosphere to form fumes of sulphuric acid. This reaction forms the basis of the manufacturing process of H2SO4. The read-across hypothesis is therefore that SO3 will instantaneously transform into H2SO4 upon contact with water (i.e. in aquatic ecotoxicology tests), thus any observed effects will be directly attributable to sulphuric acid. It is therefore justifiable to derive hazard conclusions from sulphuric acid data, with regard to ecotoxicological endpoints.

The zooplankton community was analysed by identifying the species and counting them. A NOEC for population repartition (from copepod to cladoceran dominance) was pH 5.59 (equivalent to 0.13 mg/L). This NOEC integrates not only reproductive success, but also prey/predator relationships, (presence/lack of suitable food as smaller invertebrates or aquatic plants/algae, presence/lack of fish predators). The NOEC also integrates the effects of successive one-tear exposures to pH 6.49, 6.13, 5.93 and 5.64.

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
Increase in the abundance of cladocera at pH 5.1 in experimentally-acidified Lake 223, Experimental Lakes Area, Ontario
Author:
Malley, DF & Chang, PSS
Year:
1986
Bibliographic source:
Water, Air, and Soil Pollution 30 (1986) 629-638
Reference Type:
secondary source
Title:
SULFURIC ACID CAS No. 7664-93-9: SIDS Initial Assessment Report for 11th SIAM
Author:
OECD
Year:
2001
Bibliographic source:
UNEP Publications

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
The pH of Lake 223, Ontario, Canada, was lowered from 6.7 in 1974 to 5.1 by 1981. Samples of cladocera were taken each year and the species composition and overall biomass were monitored.
GLP compliance:
no
Type of study / information:
Published paper describing experimentally derived results.

Test material

Constituent 1
Chemical structure
Reference substance name:
Sulphuric acid
EC Number:
231-639-5
EC Name:
Sulphuric acid
Cas Number:
7664-93-9
Molecular formula:
H2O4S
IUPAC Name:
sulfuric acid
Details on test material:
None available

Results and discussion

Any other information on results incl. tables

Total zooplankton biomass was not reduced by acidification and may have increased in 1980. Prior to acidification, mean ice-free season biomass was 269 mg/m2, during 1977 to 1980 it was 318, 218, 204 and 401 mg/m2 respectively. During 1981 to 1984 biomass was 279, 236 and 247 mg/m2. Although total biomass did not greatly change with acidification, total biomass of cladocerans increased during1918 to 1983. This occurred at the expense of calanoid copepods and to a lesser extent cyclopoid copepods. In 1974 adults of D. minutus were present at a biomass of 33 mg/m2. During 1981 to 1983 their biomass was 26, 17 and 24 mg/m2. Cladocerans also exhibited marked changes in species composition. The community in 1974 at pH 6.7 was dominated by Daphnia galeata mendotae with Diaphanosoma birgeiand Bosmina longirostris also present, Holopedium gibberum was rare. At pH 5.1 Daphnia catawba, H. gibberum and B. longirostris were all abundant. D. birgei and D. g. mendotaehad dissappeared or become rare. D. catawba recorded for the first time in 1980 was usually the sole daphnid at pH 5.1, it replaced D. g.mendotaealmost entirely during the 1918 to 1983 period. Chaoborus has been incidentally samples along with the zooplankton, there is no evidence it changed markedly in abundance with acidification.

Applicant's summary and conclusion

Conclusions:
The reported study is adequate in demonstrating the effects of lowering pH on the compostion and structure on cladocera.
Executive summary:

The zooplankton community was analysed by identifying the species and counting them. A NOEC for population repartition (from copepod to cladoceran dominance) was pH 5.59 (equivalent to 0.13 mg/L). This NOEC integrates not only reproductive success, but also prey/predator relationships, (presence/lack of suitable food as smaller invertebrates or aquatic plants/algae, presence/lack of fish predators). The NOEC also integrates the effects of successive one-tear exposures to pH 6.49, 6.13, 5.93 and 5.64.