Not sure. I was told to only use food grade barrels.

Yeah, that's what I thought too...I mean, these are food grade barrels but for some reason they had latex paint stored in them. So, does that make them no longer food grade?

(It is a food grade barrel with a layer of latex paint inside).
Most unfortunate. The paint itself when dried is not necessarily harmful but could get ugly and clog your hose/drain system. Sometimes paint will peel off in a few big sheets and sometimes adheres quite well to plastic. No easy way to remove it.
Are they big pickle barrels? I got mine from a Deli.
Is the paint completely dried? Sometimes a thicker layer might be in the bottom and skinned over leaving some wet paint under the skin...sort of a wet puddle. Dig into the bottom and see if that occurred. Sometimes that can be grabbed with a sharp object...a screw driver or other. May pull out in a big sheet.
Might just be more trouble that it is worth...

I wouldn't use them. Instead, I'd try to trade them for free ones that didn't previously have paint in them.

Usually latex can be peeled off plastic pretty easily. Once paint is dry it's quite inert--that's intentional, because it lasts longer that way. The exception is of course lead-based paint, but that was outlawed decades ago.

Agree with Hoovb, it's not a big deal. If dried latex paint was a worry, we couldn't plant near most barns, fences, houses, etc.

I would try sticking a high pressure washer wand down into the barrel and swish it around. Lay the barrel on it's side so the removed paint/water can flow out.

Fill them with water & let the paint soak overnight/ a few days. The paint should start to peel off easily. It should come off in big sheets.

Latex paint doesn't want to stick to plastic--once it is peeled off, it's gone. I would not hesitate to use them.

I wouldn't hesitate to use them either. Latex paint, even if some of it washes off in the water eventually, isn't some super toxic chemical and it isn't as if you you will be drinking it.

The issue is a molehill at best, not a mountain. But you have to do what will make you the most comfortable.

Dave.

the only problem is the clogging. It does clog anything. Latex is completely nontoxic otherwise.