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OECD 241: Larval Amphibian Growth and Development Assay

The Larval Amphibian Growth and Development Assay (LAGDA OECD 241) is desigend to analyse the effects of chemicals on amphibian growth and development from fertilisation to the early juvenile period. The endpoints are designed to detect specific modes of action related to oestrogen, androgen or thyroid-mediated physiological processes.

This test system is of particular importance for the assessment of endocrine disrupting properties of chemicals (EFSA/ECHA 2018), as this is the case for the Amphibian Metmorphosis Assay (OECD 231).

 

Test organisms

  • Xenopus laevis (african clawed frog)

 

Course of the test

The test starts with eggs in the Blastula to Gastrula stage and lasts for approximately 17 weeks. The organisms are exposed to at least four concentrations arranged in a geometric series. Overtly toxic concentrations have to be avoided in order to keep mortality under 20%. Four replicates per test concentration and eight replicates for the controls are prepared with 15 to 20 eggs in each replicate with at least 4 L of test water. The test is conducted as flow-through design.

At NF stage 62 (Nieuwkoop and Faber, 1994) up to five animals are collected for assessment. After completion of the metamorphosis, test animals are reduced to ten tadpoles per tank without assessment. Exposure continues until ten weeks after NF stage 62.

Endpoints

Whole study

  • Mortality
  • Abnormalities 

Interim larval sampling at NF stage 62:

  • Time to stage 62
  • Histopathology (thyroid gland)
  • Weight
  • Length

Test termination

  • Weight
  • Lenght
  • Liver-somatic index
  • Genotypic and phenotypic sex ratios
  • Histopathology (gonads, reproductive ducts, kidney and liver)
  • Optionally vitellogenin.

The results are suitable for the calculation of a NOEC and with an increasing number of test concentrations for the calculation of an ECx .

Guidelines and literature

  • OECD Guideline for Testing of Chemicals, No. 241: The Larval Amphibian Growth and Development Assay (LAGDA).