“ co2 in is trouble too much co2 concentration IN concrete? I am not chemist but could this be another cancer provoking mean? I hope not. (read full comment) ” 

Posted on August 31, 2010 at 5:26 AM EDT

“ safe? Are they really safe? what kinds of reactions would be possible in the long run? can they effect the genes? I don't want my 19th... (read full comment) ” 

Posted on August 31, 2010 at 5:22 AM EDT