Avoid using PVC Answered
I see a lot of projects that use or re-use different grades of PVC pipe due to its easy use and availability. Free or cheap PVC seems to be a good material choice for those who lack the tools and skills needed for metal or wood work. I suggest that builder rethink this choice. Exposure to PVC is dangerous to your health. Fumes and dust from cutting, drilling and accidental burning or overheating PVC are known to cause cancer.
A few points:
PVC production is the largest use of chlorine gas in the world.
Chlorine production consumes enormous amounts of energy.
Chlorine production causes mercury pollution.
Hazardous by-products are formed throughout the PVC lifecycle.
By-products of PVC production are highly persistent, bioaccumulative, and toxic.
PVC is extremely difficult to recycle.
PVC is one of the most environmentally hazardous consumer materials ever produced.
Different grades of PVC have different melting points, flash and glass temperatures.
At 70-80 Degrees C (~150 F), most grades begin to soften and degrade in performance. This should be taken into account when building projects that involve any kind of direct or indirect heat, including hot water, etc.
(I've edited this post to contain more useful information)