Gunner writes:

Is there any inexpensive fireproofing chemicals that can be applied to
a pair of pants for example..that wont give you cancer or make your
pecker fall off?

When I was a kid there was a formula for some homemade stuff that
had Borax in it-- we tested it on some scrap cloth and it seemed
to work reasonably well (chars but won't sustain a flame on its own).

A Google search turned up a few variations on this theme. Borax
is considered non-toxic but may be a skin irritant, depending on
the concentration.

It's water soluable so it will wash out, but if you only wear it
for welding it might be worth re-treating each time (Borax is
relatively cheap).

Example:
http://ocw.mit.edu/NR/rdonlyres/Music-and-Theater-Arts/21M-735Spring2004/77C424A5-50DD-4F58-8DB6-5ECBFEF7C258/0/flameretar.pdf
(PDF file)

Formula 1: Borax - 6 parts, 6 lbs, Boric acid - 5 parts, 5 lbs,
Water - 100 parts, 12 gallons. Steep fabric in cool solution
until impregnated. Heavy applications by spray or brush are
usually reasonably effective. Repeat if necessary. This is good
for theater scenery fabric, and recommended for rayon and natural
fabrics. Yields a 8 - 12 % weighting.

Formula 2: Borax - 7 parts, 7 lbs, Boric acid - 3 parts, 3 lbs,
Water - 100 parts, 12 gallons. Water can be varied according to
absorptive capacity of fabric. For rayon and sheer fabrics, these
same amounts of borax and boric acid can be used with 17 gallons
of water. Hand-wring for an 8 - 10% weighting on fabric.
Flexibility and softness will be retained without dustiness, and
also microorganism growth is prevented.