Michael Greger, the director of public health and animal agriculture for the Farm Animal Welfare division of the Humane Society of the United States, wrote a letter to the editor of the Stamford Advocate regarding a recent article about the recent national E. coli outbreak stemming from spinach.

In the letter, he states that:

“Any diseases found on produce likely came from contamination with livestock fecal material. Our intensive confinement system of industrialized animal agriculture produces more than one billion tons of manure each year in the United States — the weight of 10,000 Nimitz-class aircraft carriers. We crowd billions of animals a year into these stressful, filthy conditions. No wonder we are plagued with the increasingly common emergence of infectious, food-borne disease.

Factory farms are a public health menace. We shouldn’t have to overcook our food.”