This thread is all making it quite clear to me...

Here are my findings:

Steel... The unsinkable Titanic was made of steel...it sank because of ice and water.

Carbon Fiber... As said in a previous posts some Airbus plane crashed because of it.

Aluminum... In the cosntruction industrty, aluminum ladders are used daily. Their failure rates have led to deaths among thousands of workers.

Lead... Acute lead poisoning from a gun or just regular lead poisoning from licking paint.

So... I propose we start building framesets out of Tightbond III glue (because it's waterproof) and popsicle sticks. I assume this is by far the most safe material on the planet to build anything. Kids eat popsicles (they love them) and kids eat glue (they love it too) but we (the popsicle and glue eaters) have all grown up just fine! I will be working on a prototype and a patent!!!