We’ve been hearing about the toxicity of Teflon® cookware for a while now, with many thousands of us trying to find substitutes such as triple ply steel and hard anodised cookware among others. The reason behind this search is the rumour that Teflon® is a nasty thing and can cause health problems. I did some digging. Please check my references below to ensure my conclusion is correct.
Do you want to find out if using worn-out non-stick utensils is safe? Click here.
As it turns out, Teflon® or Polytetrafluoroethylene (PTFE), can be quite safe by itself even when eaten due to the following properties. 
- Heat resistant
- Soft and flavour-less
- Resistant to very strong acids
- Extremely non-reactive
- Very little friction
That, was the good news. The bad news is, PTFE fumes can indeed be harmful. If overheated and the fumes are inhaled, it can cause medical issues [3, 5, 6], and so can inhaling PTFE as a spray [2, 4].
- Case #1: A 26 year old woman developed pulmonary issues after cooking food in a microwave. The microwave was found to have a component made of PTFE, which was overheated and emitted fumes. 
- Case #2: Ten workers developed respiratory symptoms after using a spray to waterproof furniture. 
- Case #3: A 29 year old man developed lung issues after inhaling PTFE fumes from an overheated non-stick frying pan. 
- Case #4: A 46 year old man developed lung issues after working with PTFE spray. 
- Case #5: A 35 year old man developed pulmary edema (water logging of the lungs) after inhaling fumes from an overheated non-stick pan. 
As it turns out, eating the stuff may be fine, though inhaling it as is or as heat fumes is likely to cause ill effects to our health, especially the lungs. It is therefore important not to let your non-stick cookware overheat. If this does happen:
- Switch off the heat
- Do not breathe in the fumes at any point
- Switch on an exhaust fan immediately
- Place the overheated utensil in a well ventilated outdoor area until it cools down
- Do not put water on the overheated utensil
Conclusion: It’s alright to use non-stick cookware. It’s not alright to let them overheat.
- Polytetrafluoroethylene Ingestion as a Way to Increase Food Volume and Hence Satiety Without Increasing Calorie Content
- Pneumoconiosis in a polytetrafluoroethylene (PTFE) spray worker: a case report with an occupational hygiene study
- Inhalation trauma due to overheating in a microwave oven
- Pulmonary injury associated with spray of a water-based nano-sized waterproofing product: a case study
- Polymer fume fever
- Polytetrafluoroethylene fume–induced pulmonary edema: a case report and review of the literature