OECD TG 416 is the “Two-Generation Reproduction Toxicity Study ” standard, which is included in Section 4 (Health Effects) of the OECD Test Guidelines for the Testing of Chemicals. The test aims to evaluate the effects of a test substance on reproductive functions, pregnancy, birth, lactation, and the development of offspring across two consecutive generations (P, F1, and F2).
Note on Regulatory Status: OECD Guideline TG 416 has been superseded by the OECD and largely replaced by OECD Guideline TG 443 (Extended One-Generation Reproductive Toxicity Study, EOGRTS). Nevertheless, TG 416 continues to be used as a reference in certain regulatory frameworks for the evaluation of existing dossiers and the interpretation of historical two-generation data sets. For this reason, this service page addresses both the scientific content of the guideline and its current practical application.
The basic principle of the test is to administer the test substance to male and female animals of the P generation, beginning in the period prior to mating, to mate them, and to produce the F1 generation. The F1 generation is also exposed to the test substance, mated, and the F2 generation is thus produced. In this way, the reproductive functions and development of the offspring are observed over two consecutive generations. The evaluation is typically conducted on rats.
The basic parameters evaluated in the study are as follows:
Parent (P) and F1 generations – Reproductive function:
- Gonadal Function and the Estrus Cycle
- Mating Behavior, Mating and Fertility Indices
- Fertilization and Pregnancy Indices
- Sperm parameters (count, motility, morphology)
- Histopathological Examination of the Reproductive Organs
Pregnancy, Birth, and Lactation:
- Gestation Period and the Birth Process
- Data on live births, stillbirths, and resorption
- Lactation performance and survival rate of young animals
- Survival rate before and after weaning
Next generation (F1 and F2):
- Viability and Survival Rate After Birth
- Body Weight and Growth Curve
- Indicators of physical development (opening the eyes, teething, etc.)
- If applicable, record the gender distribution and any developmental abnormalities
- Reproductive Performance of the F1 Generation (Production of the F2 Generation)
The experimental design includes a negative control group, a solvent control group, and, if applicable, a positive control group; dosages, group size, and duration of treatment are justified in accordance with the regulatory requirements of OECD Guideline 416.
Why is this study being conducted?
OECD Guideline 416 is implemented for the following scientific and regulatory purposes:
Assessment of Reproductive Toxicity: Determination of the Effects of the Test Substance on Male and Female Fertility Over Two Generations
Assessment of developmental effects: Identification of effects occurring during pregnancy, birth, and lactation
Monitoring intergenerational effects: Assessment of reproductive performance in the F1 generation and development in the F2 generationSupport for regulatory submissions: Use in safety assessments of chemicals, pesticides, biocidal products, and industrial chemicalsAnalysis of historical data: Evaluation of existing TG 416 studies in the current regulatory context and comparison with TG 443 dataThe “weight-of-evidence” approach: Contribution to risk assessment in conjunction with additional data on reproductive and developmental toxicity, physicochemical properties, and exposure assessment
Although OECD TG 416 evaluates reproductive functions and the development of offspring over two generations, its ability to provide insights into functional developmental endpoints, endocrine disruption, and late-onset effects is limited.
Therefore, current regulatory assessments are based on TG 443 and the associated guidelines. The results should be interpreted within the context of a comprehensive toxicological assessment.
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As part of our nano-testing services, we conduct analyses in accordance with OECD TG 416 as well as the procedures outlined in OECD TG 443—the current equivalent of this standard—with scientific rigor within our accredited laboratory infrastructure and quality management system. Our scope of services includes the following:
Study Design and Protocol Development
- Preparation of a test report in accordance with OECD TG 416 and its current equivalent, OECD TG 443
- Determination of the dosage range and establishment of the main experimental design based on the physicochemical properties of the test substance
- Establishment of negative controls, solvent controls, and, where appropriate, suitable positive control groups
- Scientific rationale for the selection of species, route of administration, dosages, and duration of use
- Compliance with Ethical Review and Animal Welfare Requirements
For your studies conducted in accordance with OECD TG 416 and its current counterpart, OECD TG 443, you can contact Nano-Test to obtain information on study design, species selection, sample acceptance criteria, testing schedules, and reporting procedures.