Today, together with Causes.Com, I’m launching a new petition to take on what government officials and medical experts are increasingly calling a growing threat to public health: The overuse of antibiotics on animal farms. The petition is expected to reach as many as a half million Internet viewers this week. Petition signers are asking Walmart’s CEO, Mike Duke, to demand that its meat suppliers only use medically necessary antibiotics when an animal is sick, rather than to prevent sickness because animals are crammed in conditions that breed infection.

At present, concentrated animal feeding operations, or factory farms, routinely administer low doses of antibiotics to livestock in feed and water. The practice, long defended by the meat industry, poses significant associated health risks. Continual exposure to unnecessary antibiotics eventually makes disease organisms like E. Coli and Salmonella resistant to critical, life saving drugs.

Many of the antibiotics used in factory animal farming are the same types of drugs used to treat people when they are sick. When humans are exposed to these new antibiotic- resistant superbugs, there’s a real risk the drugs previously relied on to kill the disease will no longer work.This means if you get sick, antibiotics might no longer make you better, and we’re seeing this happen already.

Just this week, the Centers for Disease Control (CDC) released a landmark report warning that antibiotics are being over-applied and potentially squandered, both in human medicine as well as livestock production, which is responsible for over 70 percent of all antibiotic use in the United States. The CDC report claims that “much of antibiotic use in animals is unnecessary and inappropriate and makes everyone less safe.”

For decades, health officials have called for a phase-out of the practice of administering antibiotics to compensate for high concentrations of animals in conditions ripe for breeding disease. Antibiotics, they argue, should be used only with a medical need and veterinary consult. But Congress and the Food and Drug Administration have been unwilling to regulate the powerful meat industry.

Please join me in asking Walmart, as the country’s largest and most powerful food retailer, to use its market clout to protect antibiotics—one of humankind’s most valuable medical resources—and support healthier meat production in the process. The future of our planet and ourselves is at stake.