"900 pencils" and "50 liters": flashy, unproven
This list turns the mass of body elements into household objects: carbon into pencils, fat into soap, water into a barrel. But the claims depend on body mass and assumptions about composition and manufacturing; the flea-killing and toy-cannon claims require additional hazardous chemical assumptions. No reliable method supporting the whole precise list was located.
It is accurate to say that people are made of water and chemical elements, but proportions vary among individuals and with age. The list should not be treated as a laboratory-verified quantitative fact or as a practical recipe.