Weedkiller question?

[CiaraPatricia]

My dad put weedkiller and feed on the grass in the front of my house a while ago. Since then he has cut it twice, so he thinks it'd be ok now for the guinea pigs to eat if I wanted to give them a few handfuls or some dandelions (obviously the weedkiller didn't work that well!) He thinks the rain will have washed away the weedkiller and that the grass that was it was put on has all been cut now, so it's safe, but I'm not so sure.

But I'm worried that the grass will have absorbed the weedkiller or something, and would be poisonous? Does anyone know if it's dangerous or if I'm just being paranoid? I thought I'd check here, cos I think it seems a bit risky.

My guinea pigs have a run on the grass in the back garden (weedkiller free) but there's only a small strip of grass and they have it all eaten in a week and I have to put them back on concrete for another week to let it grow. I also have rabbits, so it'd be handy if I could use the grass out the front too. Obviously I won't unless someone can tell me it's definitely safe.

Thanks and hopefully someone knows