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On the fauna

Acute and chronic toxicity on Fauna?

According to the species (crustaceans, fish's, soil organisms,…), the exposure pathways (ingestion, direct contact with the skin, gills,…) to organisms are different. The soil organisms such as worms are exposed by direct contact or by ingestion of soil particles. The aquatic vertebrates, for example fish's, may be subject to nanomaterials across the epithelial cells of the skin and of the gills.

The main parameters indicating acute and chronic toxicity are respectively the CL50 (lethal dose 50) and the NOEC (No Observed Effect Concentration):

  • CL50: concentration necessary to kill 50% of the organisms which are exposed after a specified exposure duration,
  • NOEC: threshold below which the effects in time are not observed.

Experiment example

Percentage of survival daphnia magma exposed to nanosilver as the function of time for several concentrations [B.K. Gaiser et al., Environmental Toxicology and Chemistry 31 (2012) 144-154].

B.K. Gaiser et al. [B.K. Gaiser et al., Environmental Toxicology and Chemistry 31 (2012) 144-154] have shown that the mortality of daphnia magma exposed to silver nanoparticles is function of their concentration:

  • 1 day of nanoparticle exposure with concentrations of 3 and 10 mg/l are sufficient to kill 50 % of exposed organisms, 100 % after 1,5 day,
  • 4 days are necessary to kill 50 % of exposed organisms for a concentration of 0,1 mg/l.