The subject of antimicrobial resistance in food animals is a contentious one that involves both science and emotion. “There are times when science may not help us when values are at play,” explained Scott Hurd, DVM, PhD, Iowa State University, at last week’s "National Institute for Animal Agriculture’s Antibiotic Use in Food Animals: A Dialogue for a Common Purpose" conference in Chicago.
Hurd noted that when science cannot help us make a decision is when consumers’ values or emotions play a larger role in their choices. “Why weren’t people listening to the objective data that the antimicrobial resistance risk is minimal?” he said. “They didn’t understand what I was saying and they didn’t want to. They had some other motivating factors which may be political, religious or ‘life ought not be that way’. Science may not help in that regard.”
Some of the value-based questions Hurd says that consumers have are:
- Is modern farming acceptable?
- Who should benefit and how much?
- How much veterinary oversight is enough?
- What is over or unacceptable use of products?
- What is acceptable risk?
“Concern about antimicrobial resistant bacteria is not equivalent to risk,” Hurd said.
Hurd explained that antimicrobial-resistant bacteria are found on farms, in ground water, deep in ocean, in arctic and sub-arctic seals, wild boars, baboons and 30,000-year-old permafrost. “Hazard does not mean risk. Water can be a hazard. What makes it a hazard? The dose. For example, a glass of water is not a risk, but drowning in a lot of water is. The poison is in the dose. Risk is about probability and consequence. You can’t have risk without exposure and dose. Hazard creates concern. Concern does not equal risk.”
Hurd said the FDA Guidance 152 on antimicrobial resistance says that risk assessment estimates the probability that resistant bacteria are present in the target animal as a result of drug use and humans ingest the bacteria in question from the relevant food commodity and human exposure to resistant bacteria results in an adverse health consequence.
“If any one of those goes away, the risk goes to zero,” he said. “Without a causal pathway, you have no risk. Risk assessments must be implemented on case (bug)-by-case (drug) basis.”
There is a relationship between animal health and human health. “Healthy animals must enter the food chain,” Hurd said. “Healthy animals make safe food. Whether we remove or changed antibiotics, if we decrease animal health there will be public health consequences, but more research is needed.”