It first started for me several months ago, the time when my Nanday mysteriously developed weakness in her feet. To this day we really don't know which cure worked, or if she recovered from it on her own.
But, the vegetables were sparking like crazy in the microwave. I was shocked that there seemed to be some kind of metal in them! I went online to see if there were recalls or some other information. I found quite a bit actually, that it is lead and cadmium. Also information on the FDA saying the levels were too low for alarm. Well, I have to tell you, I don't want to eat it! And I really don't think what might be "safe for human consumption" necessarily applies to our birds who weigh anywhere from a couple of ounces to maybe 3lbs for the large macaws. I even showed it to my avian vet. The test for lead was rather expensive and the bird had recovered so we decided not to run it.
However, this has happened with new bags of veggies several times since. And I've eaten frozen vegetables for 2 decades, being a single person, with no issues until a few months ago. The brands I've tossed out are Great Value, Green Giant and Pictsweet. I'm currently using Bird's Eye and no issues yet. It has happened with mixed vegetables, broccoli and squash.
My mom said don't eat frozen vegetables anymore, but it isn't the freezing process that's the problem. It's either the soil they are grown in, or perhaps fertilizer absorbed by the plants. If you don't put them in the microwave, you would have no way of knowing this stuff is in there!
I've seen quite a few posts here about weakness in bird's feet, so I suspect it has something to do with this lead in the vegetables thing. It happened to my bird as well. I was just lucky to catch it immediately. Now, her problem could also have been an infection or a selenium/vitamin E deficiency. There is vitamin E in her pellets and she does get foods rich in it and selenium, so that seemed odd to me. I also keep her food/water and cage very clean. I also think it could have been those vegetables.
Our birds probably could get ill from ingesting a very tiny amount of lead even if we don't. Just a heads up.