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Acute toxicity of arsenic to Daphnia pulex : Influence of organic functional groups and oxidation state
Author(s) -
Shaw Joseph R.,
Glaholt Stephen P.,
Greenberg Noah S.,
SierraAlvarez Reyes,
Folt Carol L.
Publication year - 2007
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/06-389r.1
Subject(s) - arsenic , arsenate , daphnia pulex , chemistry , toxicity , arsenite , arsenic toxicity , environmental chemistry , daphnia magna , acute toxicity , toxicology , daphnia , biology , organic chemistry , ecology , crustacean
Investigations were conducted to determine the influence of organic functional groups (i.e., methyl, phenyl) and valence state (i.e., III, V) on acute (48‐h) arsenic toxicity in Daphnia pulex. These included toxicity texts with a suite of inorganic (arsenite, arsenate) and organic arsenicals (trivalent and pentavalent methylated arsenicals, roxarsone, p ‐arsanilic acid). Toxicity, based on median lethal concentrations (LC50 values), clustered the arsenicals into three groups and followed the order (most toxic to least toxic) of monomethylarsonous acid (MMA III ), 120 μg/L > inorganic arsenic, 2,500 to 3,900 μg/L > pentavalent methylated arsenicals and phenylarsonic compounds, 13,800 to 15,700 μg/L. Pentavalent organic arsenicals were less toxic than inorganic forms regardless of functional group. In contrast, the trivalent organic species (MMA III ) was the most toxic arsenical studied. These findings, which are the first to include an aquatic organism, add to the growing body of evidence that find that MMA II I is an extremely toxic intermediate of arsenic methylation and contradict theories of arsenic toxicity that regard methylation as a detoxication event.