More samples were toxic using the chronic endpoint compared to
the acute endpoint illustrating the need for further testing with
additional sediment contact tests with chronic endpoint,although
there is currently not awide choice. Hyalellaazteca has beenused
in several studies but this species is incontrast to H. congruens not
present inEuropean freshwater ecosystems.Alternativetest
organisms for which internationally accepted test methods have
been developed and used for sediment toxicity testing are
Lumbriculus variegatus or Chironomus riparius (Egeleretal.,2010).
A major advantage of using H. incongruens in the OstracodtoxkitF™
is that the test organisms are hatched from cysts avoiding main-
tenance of in-houses tock cultures.Even though it has not yet
reached international standardization,an international intercalibra-
tion comparison has recently been conducted in preparation for ISO
standardization of the test method(JanssenandPersoone,2010).
It is not known which contaminants cause the toxic response in