Turners are not made of Teflon, but usually (in the case of plastic) of nylon ... ;-) But you probably mean Teflon dishes - pans, pots - if you use them do not exceed a temperature of about 200 ° C, they are not harmful - above 200 ° C and especially above 250-260 ° C Teflon (rapidly) degrades and on the one hand releases toxic gases and also loses its properties (especially non-wetting). So these pans are only suitable for frying at lower temperatures (and with fat), eg they are not suitable for grilling (steaks "dry") (excellent cast iron is for that).