Transgenic mice as future tools in risk assessment.

Historically, mice have served a routine and useful purpose in the research, development, and testing of biologicals, chemicals, and drugs for efficacy, toxicity, and carcinogenic risk. The literature is replete with examples using mice to study organic compounds both in short-term tests involving tumor initiation and promotion and in long-term experiments dealing with fertility, reproduction, and teratology. During the past two decades, a virtual explosion of advances has occurred in modern biology that includes the discoveries of retroviruses, oncogenes, DNA restriction enzymes, nucleotide sequence analyses, and microinjection techniques. Fusion of these milestones in genetic, molecular, and cell biology with recent developments in mouse embryology has opened novel avenues and methods of experimentation as significant additions to the risk assessment armamentarium that currently uses both prokaryotes and eukaryotes. Some promising directions afforded by transgenic mice as powerful future tools in risk assessment will be summarized below.