Chemicals used in Granite Fabrication
Chemicals are used in fabrication and installation of granite.  The most
common are  resins, sealers, sealer strippers, epoxy seam adhesives, silicone
adhesives or caulk,  and solvents used to attempt to remove stains.
Sealers cause controversy, even among stone fabricators.  Some say that if
you recommend sealing, you make stone look bad.  Others say if you don't
seal, you have staining.  Sealing products are controversial themselves.  
Some will slow down water stains, others only oil stains, and a few slow down
both.  Some can cause
spalling of the surface, due to blocking the stones
ability to breath, or expel moisture.  Also, notice that some sealers can yellow
as it ages, due to not being UV resistant.

Common solvents in sealers are trimethylbenzene,  propylbenzene, mesitlyne,
naphtha, n-Butyl acetate, Isobutyl methacrylate, PFOA, among other

Trimethylbenzene  exposure to workers is regulated at 25 parts per million.  
Adverse health effects to workers exposed to large amounts of t trimethyl
benzenes consist of  nervousness, tension, anxiety, and asthmatic bronchitis;
in addition, the peripheral blood showed a tendency to hypochromic anemia
and prolonged coagubility of blood; the peripheral blood effects were
attributed to benzene contamination of the solvent.

Propylbenzene is thought to be a
neurotoxin but is currently not regulated by
the EPA.

Mesitlyne is contained in Trimethylbenzene and is considered hazardous in
cases of ingestion, inhalation or skin contact.
Naphtha is a distilled by product of petroleum and is pretty common in paint
thinners and mineral spirits.  What makes it hard to classify as safe is the
manner in which it is distilled and separated in production, which can leave a
wide variety of contaminates.  It is regulated by OSHA to between 300 and 400
parts per million exposure to workers.

N-Butyl acetate is safe enough to be used as a food additive.

Isobutyl methacrylates are fairly safe, mainly fire and inhalation irritants.

Benzine, not to be confused with Benzene, is a common solvent with some
health risks including intoxication and peripheral nerve disorders and central
nervous system depression. Symptoms of overexposure include loss of
appetite, muscle weakness, impairment of motor action, dizziness and
drowsiness. May also cause throat irritation.  Skin contact may cause local
irritation with burning sensation in mouth, esophagus, and stomach. Vomiting,
blurred vision, and diarrhea may also occur. Cases of chemical pneumonia
have been reported from ingestion of this substance. Nervous system
disorders paralleling those from inhalation exposure may also occur.  Benzine
was experimented with during the second World War in some
camps to kill people with benzine injections.

PFOA is the abbreviation for
Penta Deca Fluorooctanoic acid, the chemical in
Teflon that is of such concern recently.

The Material Safety Data Sheets for these products tell the entire story.   
Federal law require honesty and complete disclosure in MSDS forms, so when
looking for a sealer forget the marketing claims and check the MSDS for the
real story on the safety of the materials.

Material Safety Data Sheet warns that inhalation or ingestion of large
amounts of their product can cause blindness or even death.  In the list of
incompatible materials for their product are several common minerals found in
granite such as aluminum,  alkalies, and  water.

granite sealer MSDS warns of the usual ranges of risks of their product.

Granite sealers are fragile, and the same sealer must be used to re coat on a
regular basis.   If the sealer brand and type are unknown, a common problem,
the entire top must be stripped with Methylene Chloride.

Sealers also must be stripped when the sealer starts to yellow or when too
much has built up on the surface.  The most recommended sealer stripper is
Methyl Chloride, which does a good job but is considered highly hazardous
enough that the Dept of Labor recommends
continual testing of the air while
using it to prevent exposing workers to more than 125 parts per million in the
air for short terms, those workers using it on a regular basis can be exposed to
no more than 25 parts per million.  Let's just say that while you're up to your
elbows in this stuff while stripping your countertops exceeds these levels.

Methyl Chloride has a
very long half life, three to four months, so even if you
hire this job done by professionals, your family will still be exposed to this
chemical for a very long time.  Remember that half life means that only half of it
is gone, the next half will take another three to four months and so on.  
Potentially, your home could test positive for this chemical years after the
sealer was stripped.

Resin treatment began as a technological advance to increase yields in
quarries, to allow for the use of stones that were previously unsuitable in
certain applications, and to provide a slab that is stronger in general.  Many
manufacturers of resin products offer problem-solving enhancers to “cover up”
the flaws,  which lead to "doctored" stone issues.

One stone site said
this about resined stones :

"The disreputable processing plants, on the other hand, are just capitalizing on
a new process to cover up below-standard material, hoping you won’t know the
difference or worse, dumping this sub-standard material through third party
exporters, hiding behind anonymity. They have found a cheap alternative to
costly epoxies and often don’t know or care what this product is made of. They
know they can get away with this because they export to people who don’t
understand the resin-treatment process; they only know that “something” has
been done to the slab."

Resins used in filling pits and crevices in stone slabs can be epoxy or polyester
based.   The safety hazards of epoxy and polyester resin and hardeners will be
covered below.

An interesting fact is that there are currently no standards to determine what
the minimum bond strength of the resin  to the actual stone should be.

Seaming adhesives can be
epoxy based, Super Glue (Cyanoacrylate) or
polyester based.

The epoxy itself is pretty harmless once cured, yet the epoxy contains
Bisphenol A  and epichlorohydrin both of which have been linked to  
oestrogenic activity,  alteration of male reproductive organs, early puberty
induction, shortened duration of breast feeding, and pancreatic cancer.  It is
also know as a  endocrine disruptors which are exogenous substances that act
like hormones in the endocrine system and disrupt the physiologic function of
endogenous hormones. Studies have linked endocrine disruptors to adverse
biological effects in animals, giving rise to concerns that low-level exposure
might cause similar effects in human beings.

The Super Glue adhesive contains formaldehyde, but is safe enough to be
used for closing wounds instead of stitches.

The polyester based are pretty safe, the catalyst nor the resin are
not OSHA
regulated.   It will put off dangerous fumes if it burns, but what doesn't?  
Polyesters are also the least expensive but can yellow with age.

Depending upon the formulation, silicone caulking may contain toxic
ingredients that are released only when burned.  The solvent is plain old
vinegar that has a strong smell but no toxicity.  So silicone is pretty safe.

Poultice solvents can be lacquer thinner, alcohol, mineral spirits, Methyl
chloride, ammonia, acetone, or  peroxide based.  Of these, Methyl chloride has
been discussed, acetone is fairly safe, peroxide is safe at the percentages
used, and the ammonia is clearly one of the more dangerous.  Mineral spirits,
lacquer thinner and alcohol are mainly fire hazards.

In the end, the epoxy materials used in the seam adhesive and resin coating
and the chemicals used in the sealers are the most dangerous followed by any
strippers used to maintain the sealed surfaces.  Despite the stone industry
claims, health risks are present as proven by the industries own MSDS
Check out the latest on the chemical and heavy metal issues at our forum.   We
will be starting heavy metal testing  on granite countertop slabs this spring.