Hazards of formaldehyde
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For several months there have been recurring threads concerning health and
safety issues that have troubled us greatly at Anatech Ltd. The general
theme has been to make light of toxicity claims, provide anecdotal comments
about having survived many decades of working in labs, and giving the
impression that current health and safety regulations are at best a pain
and probably are the cunning products of misguided governmental agencies.
There are approximately 1100 HistoNet subscribers (HistoLogic 31(2):37).
Twenty or so seem to be regular contributors whose comments are given
considerable credence by many of the readers. Regretably these regulars
are creating an impression that can only harm the great strides we have
made in the last 20 years toward making our labs safe. I cannot change the
attitudes of many of these regular contributors, so I address the following
comments to the rest of you, the 1080 or so reader, whose minds may still
be open to reason and documented fact.
The great hazard of formaldehyde is not its proven carcinogenicity. Anyone
interested in formaldehyde's effects on humans should read the preamble to
OSHA's Formaldehyde Standard (Federal Register 52(233):46168-46312;
December 4, 1987). According to studies cited therein, formaldehyde has
been directly implicated in causing tumors in the lungs, naso- and
oro-pharynx and nasal passages of humans occupationally exposed to levels
of formaldehyde not unlike conditions existing in histology laboratories a
few decades ago. Repeated and prolonged exposure increases the risk.
True, the risk is small, and with the improved ventilation in most US labs
(at least), one could justify ignoring the issue altogether. I personally
do not care to increase my risk, but the significance is truly minor.
However, Formaldehyde presents a vastly greater risk to histotechnologists
by being a potent sensitizer. Once sensitized, you will probably
experience worsening symptoms for the rest of your life even if you leave
the field. You cannot get away from formaldehyde. It off-gasses from most
building products except untreated lumber. It has been widely used in the
permanent press treatment for fabrics (although glyoxal is replacing it
there as it is in histological fixatives). It comes out of carpeting
drapes and upholstery. You will get more colds, suffer with them longer,
may develop asthma, or experience worsening asthmatic attacks. OSHA
reported in 1982 that 79% of the histotechnologists studied showed
respiratory and dermatological symptoms consistent with
formaldehyde-induced sensitization, a 2-fold increase over the control
group. Exposure levels for those histotechs were 0.2-1.9 ppm, levels that
were really rather moderate for the time (pre-1987).
The Formaldehyde Standard was written in great part because of the
unacceptable conditions in pathology labs. Industry had long since cleaned
up its act. The standard's preamble specifically singles out pathology
labs as being among the worst for workplace exposure.
Perhaps many of you do not remember or were not in the field before 1980.
A few techs were concerned about chemical exposures, but were mostly
stymied by glib administrators and uncaring co-workers whose attitudes were
strikingly like those being aired on the HistoNet today. NSH struggled
many years to bring these concerns to light, organizing a Health & Safety
Committee, sponsoring studies of formaldehyde and xylene exposure,
providing workshops and lectures on all aspects of health and safety, and
compiling lists of resource materials and personnel. The real leaders of
this field have taken the subject very seriously. Please don't go back
down that road in reverse; if you do, do it alone.
I want to set the record straight. Formaldehyde can be worked with safely.
No histotech should ever need a respirator. Simple, properly designed
ventilation can easily keep vapor levels below the OSHA Action level of 0.5
ppm averaged over 8 hours. If you stay below that level (and the STEL of 2
ppm over 15 minutes), you avoid almost all of the standard's requirements
and have a safe workplace at least for the inhalation of formaldehyde
Skin contact with formaldehyde is another issue altogether. Latex surgical
gloves offer NO protection (breakthrough time is seconds to a few minutes).
Very thin nitrile gloves are probably marginally better, but breakthrough
times are not available. This form of exposure is the cause of most
modern-day sensitization reactions to formaldehyde. Butyl and nitrile
gloves comparable in thickness to dishwashing gloves will protect you for
most histological tasks involving formaldehyde (Schope et al., 1987,
Guidelines for the selection of chemical protective clothing, ACGIH,
Cincinnati, OH). Unfortunately, grossing is difficult with these
Making your own formalin makes economic sense only until you factor in
labor, overhead and compliance costs. Couple that with QC issues and
suddenly the commercial product from a reputable vendor is a lot more
attractive. As Randy Kline has ably pointed out, having it made by a
company conforming to Good Manufacturing Practices and controlled by the
FDA goes a long way toward providing you with peace of mind that the
solution actually does contain 3.7% formaldehyde. You can buy it
cheaply,but you will get exactly what you paid for...as always.
Finally, concerning the assaying of formalin, there are several methods
available but few will provide the specific concentration with a given
level of precision and accuracy. Of the latter, only one is feasible for
general use (the others require glassware and calibrated standards that you
don't want to mess with). Anatech Ltd. and B/R Instruments have an assay
kit that unambiguously determines the concentration in increments of 2
percentage units (e.g., 9.0-10.9%). The test takes a minute or two to
perform once you become familiar with it.
Sakura recently came out with test strips, like pH dip sticks, which are
much easier to use but may be difficult to interpret (the color differences
between 7.5% and 10% are debatable, the colors are transient, and the
important color develops in the center of the stick's patch, not the edge,
making comparison with the picture difficult).
If safety issues are of concern or interest to you, obtain a copy of our
Hazmat Maunal (Dapson & Dapson, 1995, Hazardous materials in the
histopathogy laboratory, 3rd edition, available from Anatech Ltd.). The
answer to virtually every health, safety and disposal question that has
ever appeared on the HistoNet can be found within its 253 pages.
I could continue with another tiresome page on xylene, but I'll spare you.
1020 Harts Lake Rd.
Battle Creek, MI 49015
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