Validated Non-animal Alternatives
|
Methods
|
Test Purpose
|
Validation Authority
|
OECD TG
|
Other
|
| Estrogen Receptor (ER)-alpha Transcriptional Activation Assay for Estrogenic Agonist-Activity |
Endocrine disruptor screening assay |
OECD/EPA
|
OECD TG 455
|
US EPA OPPTS TG 890.1300
|
| H295R Steroidogenesis Assay |
Endocrine disruptor screening assay |
OECD/EPA
|
OECD TG 456
|
US EPA OPPTS TG 890.1550
|
| Aromatase Inhibition Assay (human recombinant) |
Endocrine disruptor screening assay |
|
|
US EPA OPPTS TG 890.1200
|
| BG1Luc ER TA Test Method |
Endocrine disruptor screening assay |
ICCVAM (2012)
|
Draft OECD TG
|
|
The human cell-based estrogen receptor-alpha transcriptional activation assay described by OECD TG 455 "provides mechanistical information, and can be used for screening and prioritization purposes."
In addition, five in vitro/ex vivo endocrine disruptor screening assays have been accepted as part of an in vitro and in vivo test battery, the US EPA Tier 1 Screening Battery. These assays are accepted as test guidelines by the US Environmental Protection Agency (EPA) Office of Prevention, Pesticides and Toxic Substances (Series 890 OPPTS), and include the following methods:
- Estrogen receptor binding – rat uterine cytosol
- Estrogen receptor - (hERα) transcriptional activation - human cell line HeLa-9903
- Androgen receptor binding – rat prostate cytosol
- Steroidogenesis – human cell line H295R
- Aromatase – human recombinant microsomes
The validation status of the stably-transfected estrogen receptor transcriptional activation assay, the BG1Luc Estrogen Receptor (ER) Transcriptional Activation (TA) test method, was reviewed by an ICCVAM international scientific peer review panel in March 2011. "The panel agreed with ICCVAM draft recommendations that the BG1 test method could be used as an initial screen to identify substances with the potential to enhance [agonist activity] or inhibit [antagonist activity] activation of the estrogen receptor." The panel concluded that the "accuracy of this assay is at least equivalent to the current ER TA included in regulatory testing guidance" [OECD TG 455]. The NTP Scientific Advisory Committee on Alternative Toxicological Methods concurred with these recommendations, and ICCVAM transmitted final recommendations on this test method to US agencies in 2011. The BG1Luc ER TA test method has been adapted to a high throughput screening (HTS) format. It is expected that this assay will be incorporated into Tox21 screening.
ECVAM and the European Commission supported a validation study of a full length recombinant human estrogen receptor alpha (hERα) estrogen binding assay. The data from this study are available on the ECVAM website.
JaCVAM is in the process of reviewing several of the existing in vitro methods for identifying endocrine active substances (EACs).
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