VPD papers

The ACGIH (American Conference of Governmental Industrial Hygienists,
Inc.;) Threshold Limit Value for cyclohexylamine in 1994 is 10 parts per
million, the same as for benzene, chloroform, hydrogen cyanide and
naphthalene.  Maybe the ACGIH is wrong, but we do not *know* that.  A
good principle to follow, when you do not know whether something is
harmless, is to hold off until it has been adequately investigated.  In
my opinion, VPD sheets have not been adequately investigated.

I have used VPD sheets.  On March 24, 1977, I wrote to NIOSH in
Rockville, MD, saying, in part, "I have had a headache for a week now,
ever since I last handled the stuff, and I never get headaches unless I
am sick." I asked for advice, and they sent me three inconclusive
journal articles. Nobody followed up because nobody was doing a study on
the topic.  The absence of evidence to the contrary is not the same as
an endorsement.

I do want to make it clear that cyclohexylamine is not the same as
cyclohexylamine carbonate (CHC).  The ACGIH does not list the carbonate.
But in the 1970 evaluation of the carbonate (Restaurator, v. 1), it is
stated on p. 160 that "CHC hydrolyzes to cyclohexylamine, an odorous and
toxic chemical, on exposure to moist air."  Anyone who breathes the
vapor would be moistening it by breathing it in.  Maybe the authors were
mistaken, and maybe there is evidence on the other side, but this is
enough evidence to make me want to be on the cautious side.

                                  ***
                  Conservation DistList Instance 8:39
               Distributed: Wednesday, November 23, 1994
                        Message Id: cdl-8-39-002
                                  ***