METHACRYLIC ACID ESTERS:
METHYL METHACRYLATE
N-BUTYL METHACRYLATE
BACKGROUND INFORMATION
ABOUT THIS PAMPHLET
Methacrylic acid and its esters have proven to be versatile chemicals with
widespread use. Rohm and Haas, and others, have sponsored and
conducted scientific studies on the health and environmental effects of
these products. This pamphlet provides a summary of regulatory,
exposure, and technical information for use by government officials,
health professionals, and others who would like a brief introduction to the
data. This pamphlet includes data that Rohm and Haas is aware of as of
the date of publication. Rohm and Haas has been careful to accurately
summarize the data and conclusions. However we are making this
information available to you without any guarantee that they are
appropriate for your purposes as conditions and methods of use of our
products are beyond our control. In addition, newer data may be or
become available. Rohm and Haas disclaims any liability for use of this
information by persons outside of Rohm and Haas.
Users should also consult the Material Safety Data Sheet (MSDS), and
other available brochures, for up-to-date information and precautions for
safe handling and use of these chemical products. If additional
information is desired, please contact your Rohm and Haas Account
Manager or the appropriate Regulating Agency for assistance.
Page 1
INTRODUCTION
Methacrylic acid esters have served as essential building blocks in the production of
some of our most commonly used industrial and consumer products.
Methyl methacrylate is used in production of polymethyl methacrylate (poly MMA)
polymers (under either cold or hot polymerization conditions) or copolymers used in
manufacture of acrylic sheet and acrylic molding, clear plastics (Lucite? Perspex?
Plexiglas?, and in extrusion powder, acrylic surface and paper coatings, latex paints,
printing inks, floor polishes, dental restorations, adhesive cements, and surgical
implants. Butyl methacylate is used to modify the resulting characteristics of
polymers in many of the same applications listed above as well as in automotive
coatings and other lacquers.
Polymerization
Methacrylic monomers such as methyl methacrylate (MMA) and butyl methacrylate
(BMA) are highly reactive chemicals and, therefore, are used nearly exclusively as
intermediates in the production of other materials. For example, individual molecules
of methacrylic esters, called "monomers," readily combine with themselves or other
monomers to form long chains of repeating units, or "polymers." The polymers have
different physical and chemical properties than the constituent monomers. Such
polymers are used for glazing and even cutting boards used in many kitchens.
These polymers can be used in the production of goods that for decades have
provided added benefits and convenience to consumers and manufacturers
worldwide.
PHYSICAL PROPERTIES
Methyl n-Butyl
Methacrylate Methacrylate
Molecular Weight 100 142
Molecular Formula C5H802 C8H15O2
CAS Number 80-62-6 97-88-1
101 163
Boiling Point (癈)
-48 -50
Freezing Point (癈)
Density (20/20 癈) 0.94 0.90
Flash Point (Seraflash Tester 癈) 8
Flash Point (Pensky-Martens 49
Closed Tester 癈)
EXPOSURE TO METHACRYLIC ESTERS
Page 2
Methacrylate monomer vapor has a strong odor that some consider fruity or sweet. It
is expected that this odor will lead to early detection of any potential releases. The
following table contains a list of current standards for levels to which the standard-
setting bodies consider that most workers can be exposed during an 8-hour workday
without harmful effects, as well as the results of tests used to determine the levels at
which the odor of the methacrylate esters will usually be detected. As illustrated,
methacrylate odor usually will be detected before it reaches the levels of the current
standards. While unpleasant, smelling methacrylate vapor is not necessarily
indicative that such levels have been exceeded.
Methyl n-Butyl
Methacrylate Methacrylate
OSHA Permissible 100 None determined by
Exposure Limit (ppm) OSHA
ACGIH Threshold
50, sensitizer None determined by
Limit Value?(ppm)
STEL: 100 PPM ACGIH
Odor Threshold 0.21 0.016
(ppm)
Because consumer products contain only trace levels of methacrylic esters as a result
of the polymerization process, consumers are not generally exposed to these
compounds in finished products. Although potential for exposure does exist during
methacrylic ester manufacture, transportation, and use, exposure to worker
populations and nearby communities is limited by the use of enclosed systems..
Employees and contractors involved in methacrylic ester manufacturing should wear
appropriate safety equipment and undergo special training.
In spite of the manufacturer's efforts to contain the manufacturing process, vapors
can potentially escape from leaks in the piping system, during repair or replacement
of the piping system (including tanks and reactors), or during removal of samples for
quality control purposes. Worker exposure should be monitored in manufacturing
facilities with specialized monitoring systems. Since odors can be detected at such
low levels, it is expected that leaks should be detected and repaired before the
material can cause adverse health effects
Exposure could also occur during loading, unloading, and transportation of tank
trucks, railroad tankers, barges, and drums. However, dedicated systems designed to
handle methacrylic esters are typically used for loading and unloading purposes and
procedures should be in place to prevent spills or leaks during transportation.
Page 3
TOXICOLOGY PROFILE
The likely primary routes of human exposure to the methyl and n-butyl esters of
methacrylic acid, methyl methacrylate and n-butyl methacrylate, are skin contact and
inhalation; toxicity is due to tissue damage at the site of contact. The undiluted esters
are slightly to severely irritating to the skin when applied under occluded conditions
and upon prolonged contact. In contact with eyes both methyl methacrylate and n-
butyl methacrylate have shown only weak irritation. Contact with dilute solutions of
the methacrylate esters or monomer vapors can be irritating to the skin, eyes and
respiratory tract.
These esters have caused skin sensitization, and individuals allergic to one ester may
exhibit a sensitization reaction when exposed to other esters. No cross-reactivity with
acrylate esters has been reported. There are no clinical case study reports linking
these esters to respiratory allergy.
In animal studies, the irritation caused by repeated exposure to methacrylic esters
vapor at levels exceeding the TLV?has resulted in nasal lesions.
In general, such studies have shown that the methacrylate esters are absorbed and are
rapidly metabolized to methacrylic acid (CAS 79-41-4) and the structurally
corresponding alcohol (methanol in the case of MMA and n-butanol in the case of n-
BMA). The resulting metabolites are eliminated via expired air and urine.
Toxicity associated with repeated exposures of experimental animals to n-butyl
methacrylate typically has been comprised of changes in body and organ weights as
well as clinical chemistry. Except for dermal and nasal lesions which have been
observed at the site of contact, the microscopic examination of other body tissues
post-exposure has indicated no significant difference compared to non-exposed
animals. In repeated exposure studies with methyl methacrylate, microscopic lesions
have been observed in body tissues other than those at the site of contact.
Toxicologist believe there is no relevant concern on carcinogenicity of these esters in
humans and animals. No cancer studies are available for n-butyl methacrylate.
However, on the basis of analogy with methyl methacrylate, which is metabolized to
the same metabolic product (methacrylic acid) as n-butyl methacrylate, it is unlikely
that n-butyl methacrylate will represent a carcinogenic risk. Based on that analogy,
chronic studies in animals with methyl methacrylate suggest that n-butyl methacrylate
is unlikely to have carcinogenic risk. Epidemiology data on increased tumor rates in
exposed cohorts are of limited reliability and cannot be related to methyl methacrylate
as the sole causal agent.
Page 4
Neither methyl methacrylate nor n-butyl methacrylate are expected to have adverse
effects on fertility or the unborn fetus even though some evidence of reproductive and
developmental toxicity was demonstrated in animal studies conducted with n-butyl
methacrylate at only high exposure levels.
These esters are considered "moderately" toxic to fish and invertebrates following
acute exposure. Neither methyl methacrylate nor n-butyl methacrylate will
accumulate in the environment. If released to surface water, these esters should all be
rapidly biodegraded; some portion should volatilize to the air.
Page 5
REGULATORY STANDARDS
The manufacture, transportation, and use of basic methacrylates are regulated or
addressed by a number of government agencies and other expert groups to control
exposure to workers and the environment. The following table records major U.S.
federal regulatory and similar information as of December 2007. Such regulations
frequently change, and many states and localities adopt their own regulations.
Therefore, you should consult applicable laws and regulations, as well as the
manufacturer's MSDS, for current requirements.
REGULATORY STANDARDS
Methyl Butyl
Methacrylate Methacrylate
OSHA PEL 100 ppm None determined by
OSHA.
50 ppm, sensitizer None determined by
ACGIH TLV?br>
STEL: 100 ppm ACGIH
A4 1
IARC N/A
NTP BRC no no
DOT Hazard Class 3 3
SARA/CERCLA RQ 1000 lbs. no
SARA ?13 yes no
RCRA no no
CAA ?12(b) no no
CWA no no
FDA Uses 2 yes 2 yes 2
NFPA Rating: 3
?Health 2 3
?Flammability 3 2
?Reactivity 2 2
1
Group A4 = Not Classifiable as a Human Carcinogen: There are inadequate data on which to classify the agent in terms of its Carcinogenicity in
humans and/or animals.
2
Methacrylic esters used as monomer to make specific polymers are listed for certain, specific indirect food additive uses.
3
NFPA Rating Definitions: 2/Health=Materials hazardous to health, but areas may be entered with full-face mask, self-contained breathing apparatus
which provides eye protection; 3/Health=Materials extremely hazardous to health, but areas may be entered with extreme care; 2/Flammability
=Materials that must be moderately heated before ignition will occur; 3/Flammability=Materials that can be ignited under almost all normal
temperature conditions; 2/Reactivity=Materials that (in themselves) are normally unstable and readily undergo violent chemical change but do not
detonate.
Page 6
ACRONYMS
American Conference of Governmental Industrial
Hygienists, Threshold Limit Value?br>
ACGIH TLV?br>
Clean Air Act, ?12(b)
CAA
Clean Water Act, Ё116.4, 112 App. D, 131.36, 401.15,
423 App. A.
CWA
Department Of Transportation: Hazard Class 49 C.F.R.
?72.101
DOT Hazard Class
Food & Drug Administration: 21 C.F.R. Parts 174 to
178
FDA
International Agency for Research on Cancer
IARC
National Fire Protection Association
NFPA
National Toxicology Program Biennial Report on
NTP BRC
Carcinogens
Occupational Safety and Health Administration,
OSHA PEL
Permissible Exposure Limit, 29 C.F.R., Table Z,
?910.1200
Resource Conservation and Recovery Act, 40 C.F.R.
RCRA
?61.33
Superfund Amendments and Reauthorization Act
SARA/CERCLA RQ
(1986), 40 C.F.R. ?75/Comprehensive Environmental
Response, Compensation, & Liability Act (1980), 40
C.F.R. ?02.4 Reportable Quantity
Section 313 of Title III of SARA - Toxic Release
SARA 313
Inventory Reporting & Community Right-To-Know, 40
C.F.R. ?2.
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