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A lifetime oncogenicity study in rats with acrylamide
M A Friedman1, L H Dulak, M A Stedham
1Cytec Industries Incorporated, West Paterson, New Jersey 07424, USA.
Summary
This study characterized acrylamide's carcinogenic potency in rats, confirming its role in thyroid, mammary, and testicular tumors. Acrylamide did not induce glial tumors, and the no-observable-effect level for scrotal mesotheliomas was 0.5 mg/kg.
Area of Science:
- Toxicology
- Carcinogenesis
- Oncology
Background:
- Acrylamide is a widely used industrial chemical with known carcinogenic potential.
- Previous studies have indicated acrylamide's ability to induce tumors in various tissues.
- A comprehensive understanding of acrylamide's dose-response relationship in oncogenesis is crucial for risk assessment.
Purpose of the Study:
- To accurately characterize the carcinogenic potency of acrylamide through a lifetime oncogenicity study in Fischer 344 rats.
- To identify specific tumor types induced by acrylamide exposure and establish dose-response relationships.
- To evaluate the no-observable-effect level (NOEL) for specific acrylamide-induced tumors.
Main Methods:
- A 106-week study administering acrylamide in drinking water to male and female Fischer 344 rats at varying doses (0-3.0 mg/kg/day).
- Comprehensive necropsy, gross pathology, and histopathology examinations of all study animals.
- Statistical analysis to determine significant increases in tumor incidence compared to control groups.
Main Results:
- Significant increases in mesotheliomas of the testicular tunic in high-dose males.
- Significant increases in mammary gland adenocarcinomas and fibroadenomas in both acrylamide-dosed female groups.
- Significantly increased thyroid follicular cell adenomas and adenocarcinomas in high-dose males and females, and low-dose females.
- Sciatic nerve degeneration observed in high-dose groups; no visual neurotoxicity.
- Acrylamide did not induce glial tumors, and the NOEL for scrotal mesotheliomas was 0.5 mg/kg.
Conclusions:
- This study confirms acrylamide's carcinogenicity, specifically its induction of benign tumors of the thyroid and mammary glands, and mesotheliomas of the testis.
- Acrylamide exposure did not lead to an increased incidence of glial tumors in this study.
- The findings establish a NOEL for scrotal mesotheliomas and indicate that mammary tumor increases were within historical control ranges, providing valuable data for risk assessment.