Conventional Test Method:

Two-Generation Reproductive Toxicity (OECD TG 416)

Alternative Test Method:

Name & Description:

Microsomal Aromatase Assays
(used in conjunction with either Pubertal Male In Vivo Assay or Adult Male In Vivo Assay)

The human placental microsomal aromatase assay and the human recombinant microsomal aromatase assay are in vitro assays used for measuring aromatase and aromatase inhibition. Aromatase is the cytochrome P450 enzyme complex responsible for the conversion of androgens to estrogens during steroidogenesis. Alterations in the amount of aromatase present or its catalytic activity will alter the levels of estrogens in tissues and disrupt estrogen hormone action. Inhibition of aromatase alters the catalytic activity of the enzyme and results in a rapid decrease in the levels of estrogens.

Validation Status:

US:  Validated by EPA for identifying aromatase-inhibiting chemicals (2007)

Regulatory Status:

US: The Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC) recommended that the EPA consider the use of these assays in a tier I screening test battery for the Endocrine Disruptor Screening Program (EDSP) (2007).

Effect or Potential Effect on Animal Use:

Reduction

References:

• EPA (2009) Endocrine Disruptor Screening Program Test Guidelines- OPPTS 890.1200 Aromatase (Human Recombinant).
• EPA (2007) Integrated Summary Report on Aromatase.
• EPA (2007) Integrated Summary Report for Validation of a Test Method for Assessment of Pubertal Development and Thyroid Function in Juvenile Male Rats as a Potential Screen in the Endocrine Disruptor Screening Program Tier-1 Battery.
• EPA (2007) Integrated Summary Report for Validation of 15-day Intact Adult Male Rat Assay as a Potential Screen in the Endocrine Disruptor Screening Program Tier-1 Battery.

Information Last Reviewed:

May 2012