In this show,
regarding n-Propyl Bromide (n-PB)
Margaret Sheppard was
the most awaited speaker. She is team leader for the
USEPA’s Significant New Alternatives Policy (SNAP)
Program. After more than a decade, Margaret’s team
“validated” use of n-PB as a replacement for CFC
cleaning solvents in 20072, and not an
acceptable aerosol cleaning solvent in 2008.3
But the December 2009
decision by the state of California’s OSHA group to
lower the required (not recommended) exposure limit
to 5 ppm (after nearly requiring a value of 1 ppm)
heightened expectation that might bring about a
similar pronouncement by USEPA.
That was not to be.
What was to be was of no lesser concern. It was
that: There is a draft report on carcinogenicity
available from National Toxicology Program (NTP).4
Its brief and significant finding is:
“...Conclusion: clear evidence of carcinogenic
action due to n-PB in both rats and mice....” There
was also evidence of non-carcinogenicity found.
NTP’s finding is in the
stage between peer review and publication. And it
will not be the last word on the issue of
carcinogenicity.
But NTP’s finding
combined with the previous finding between n-PB and
reproductive toxicity, which spawned the action by
CAL OSHA makes permanent conversion to n-PB as a
cleaning solvent no better than a short-term
palliative. For some, that may be OK.
EPA’s charter is not to
set required exposure limits—that’s one reason why
the 2007 SNAP decision contained a recommended and
not a required exposure limit. Exposure limits are
to be set by the National Institute for Occupational
Safety and Health (NIOSH). They have, after years of
delay, accepted the challenge of developing a
required exposure limit. The discussion may center
around whether or not the value will contain two or
a single digit of ppm.
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