If you use non-stick cookware with teflon or teflon like coating on it, yes, there is a very good chance they were poisoned by that...each of these product lines are usually found with non-stick coatings and/or working parts: automatic coffee makers, bread makers, broiler pans, cake pans, coffee warmers, cookie sheets, countertop grills, cupcake pans, curling irons, deep fryers, drip pans under stove eyes, electric skillets, fans, flat irons, grates above gas stove burners, grates on gas space heaters, heaters, hot plates, infrared light bulbs, ironing board covers, liners for ovens, pie pans, pizza pans, popcorn poppers, regular light bulbs, roasting pans, sandwich makers, slow cookers, toasters, tortilla presses, various cooking utensils, waffle irons, woks.
Here are some of the brands that are known to use teflon or teflon like non-stick coatings: Autograph, Clad, CuFlon, Ballarini, Duracote, Excalibur, Farberware, Fluron, Greblon, Hostaplon, Maxalon 2000, Perma-Cote, Princess, Resista, Revere Ware, Risoli, Sliver Slick, Silverstone, Swiss Diamond, Tefal, T-Fal, Wear-Ever and Xylon, among others.
Here's an article from 10 years ago.....“On Dec. 23rd, 2004 I was using an old pot that had most of the Teflon worn off of it to boil water to put a little moisture in the air. It was about 11:00 pm when I fell asleep. . . . .Ruby started screaming for me. I ran to the cage and pulled off the cover. . . .She uttered a few tiny sounds, then she was gone. . . . . To my horror, I saw the empty pot on the red hot coils. . . . . The pot I was using was old and worn out, but still had enough Teflon left to kill my baby from 30 feet away.”
This type of poisoning causes blisters inside a bird's air sacs and there is nothing that a veterinarian can do for them.....
Sorry that you lost your flock in this manner.....