Development and validation of OECD test guidelines on mollusc reproductive toxicity tests

Validated guidelines in line with the OECD Conceptual Framework for
the Testing and Assessment of Endocrine Disrupting Chemicals (EDTA)
have been developed for rodents, amphibians, fish, aquatic insects and
crustaceans. Only aquatic arthropods have been considered in this test
battery although the comparison of endpoints relevant for reproduction
in invertebrates often shows a much higher sensitivity in molluscs vs.
e.g. daphnids. The OECD test guideline programme has thus been
extended to cover reproduction effects of chemicals in molluscs.
Existing mollusc toxicity test protocols have been reviewed in an OECD
Detailed Review Paper that identifies two relevant candidate species for
developing freshwater tests: Potamopyrgus antipodarum and Lymnaea
stagnalis. However, this review did not clarify which toxicity test
design/conditions are the most appropriate for chemicals assessment.
Therefore, a mollusc reproduction test guideline will be developed
describing partial- and full- life-cycle test protocols in these species, so
as to propose a balanced suite of apical mollusc toxicity tests applicable
for the assessment of any type of chemical, including endocrine
disruptors, as level 4 and 5 assays of the EDTA Framework. The
guideline project is led by a consortium of experts (Germany/United-
Kingdom/France/Denmark) from academia, industry and government
stakeholders. To date, expert knowledge has been gathered and formed
the basis of draft standard operating procedures (SOPs) for the culture
and test implementation of the partial life-cycle tests in both species. Prevalidation
of these SOPs consisted in two ring-tests involving 10 partner
labs with different level of expertise in mollusc tests. Effects of
cadmium on the individual reproductive outputs were studied over 28-d
in P. antipodarum and over 56-d in L. stagnalis. Pre-validation tests
were successful in both species. Indeed, both species could be
successfully cultured at the lab. Toxicity tests provided consistent results
among laboratories for each species (e.g. homogenous and nonsignificantly
different NOECs, LOECs and EC
50
values for most
partner labs). The draft SOPs will be optimized (e.g. statistical tests
showed that the duration of the test with L. stagnalis can be shortened to
from 56-d to 35-d) and further tested for various types of reproductive
toxicants including endocrine disruptors. A broad scale ring-test will be
conducted in 2014 for both species based upon the consolidated SOPs.