I do this too; it results in much better meat. But I spoke to a specialist at the American Meat Institute who told me unequivocally that it does not result in safer meat. It’s possible you could reduce the risk by blanching the meat to kill surface pathogens before grinding it, but according to AMI (believe them or not), the risk of E. coli from large-lot ground beef is equivalent to the risk from beef ground to order.

I would add that in either case, eating the burger is probably a lot less risky than various things you do in the average day.

I agree with Matthew -- you’d better be just as skeptical about that chuck roast as about a package of plastic-wrapped, pre-ground beef. But freshly ground does taste better. And you can do it at home with a meat-grinder attachment to your stand mixer.

This is why I always buy sustainably raised meat products or eat loads of organic veggies.

Sustainably raised meats are also not immune to E. coli O157:H7. There is some evidence that grass-finished beef has lower levels of pathogenic E. coli, but it’s really just preliminary evidence. If you are concerned about getting sick from factory beef, in my opinion you should be equally concerned about all beef. Just talking about foodborne illness here, not other issues like animal welfare, antibiotic resistance, and waste pollution.