Biosafety Risks of Biopharming in Animals
The production of pharmaceuticals in the milk of transgenic farm animals has raised some biosafety concerns. First, because the expression of a transgene can be unpredictable, there is the risk that the protein product could “leak” from the mammary gland and enter the animal’s blood circulation to cause harmful systemic effects. Another concern is that male animals produced through gene transfer, or unused transgenic females, could be slaughtered for food. In that case, meat contaminated with potentially harmful pharmaceuticals might enter the human food supply.
Transgenic farm animals may also have harmful environmental effects if they escape or are released from captivity and mate with wild individuals of the same species. According to a committee on animal biotechnology convened by the National Research Council (the policy-analysis arm of the U.S. National Academies), the risk of an escaped transgenic animal becoming established in the natural environment depends on its ability to survive and reproduce in the wild. The worst-case scenario would be a transgene that increases the environmental fitness of a species that is highly mobile, readily becomes feral, and has a history of causing ecological damage. Species of greatest concern are insects, shellfish, fish, mice, rats, cats, pigs, and goats.15