In September of 2002 the New York City Department of Health and Mental
Hygiene (DOHMH), Environmental & Occupational Disease Epidemiology
Program (EODE) began receiving reports that Moisture Cure Urethanes
(MCUs), which are used to coat wood floors in homes, were generating
strong odors and raising health concerns for building residents. In
response to these concerns, EODE reviewed material safety data sheets
on various MCU products, researched the known health effects
associated with chemical ingredients of these products, and consulted
with the New York State Department of Health. Additionally, EODE,
with assistance from the Office for Environmental Investigations
(OEI), conducted an inspection during an MCU application at an
apartment building in Brooklyn, New York on March 7, 2003, that
included sampling for airborne ingredients of MCUs.

Exposure to the chemicals in MCU products can lead to a variety of
health effects depending upon the level and duration of exposure.
Brief exposures to elevated levels of these materials can result in
headaches, respiratory irritation, allergic reaction and exacerbation
of asthma; while very high and/or long-term exposures can lead to more
serious health effects such as organ damage, reproductive effects,
chemical allergies, and possibly cancer.

Environmental sampling at the Brooklyn apartment building detected
several MCU chemical ingredients in the air. These chemicals produced
noticeable odors throughout the building. The presence of the
chemicals found in the common hallways of the building may result in
irritation of the respiratory system, exacerbation of asthma in some
individuals, and headaches. In an occupied residential building these
conditions represent a nuisance.

Moisture cure urethanes contain a variety of solvents depending upon
their formulation, and typically contain xylene, ethylbenzene and
acetates. Many solvents, including xylene and ethylbenzene, have
strong odors that can be smelled at very low levels. Short-term
exposure to elevated levels can cause reversible irritation of the
skin, eyes, nose, and throat; exacerbate asthma; and cause health
effects such as headaches, nausea, and dizziness. In occupational
settings and in animal studies, exposure to very high levels of
solvents has been shown to cause neurological, kidney, and liver
damage, and can impact developing fetuses. , The International Agency
for Research on Cancer (IARC) lists ethylbenzene as a possible human
carcinogen. IARC lists xylene as not classifiable as a human cancer
agent.

Acetates, in general, evaporate more slowly and make up a smaller
percentage of the product than the other solvents. There are many
types of acetates. The acetate found in the air at the Brooklyn
apartment building (ethyl 3-ethoxypropionate) is of low toxicity, but
exposures to elevated levels can be irritating to the respiratory
system. ,


Curing Agent
MCUs contain isocyanates, typically toluene-diisocyanate (TDI) as a
curing agent. This chemical helps create the hardness of the final
urethane finish. During application and curing of the liquid MCU, most
of the TDI is combined into the polyurethane without becoming
airborne. Exposure to elevated levels of TDI in the air can irritate
the eyes, nose, throat, and lungs and cause coughing, chest tightness,
reactive airways disease, and shortness of breath. These symptoms can
exacerbate asthma. Respiratory sensitization to TDI has been
documented to occur in an occupational setting. Once sensitized,
subsequent exposures can cause an allergic, asthma-like, response.
Skin irritation and, less commonly, skin sensitization can also occur
upon direct exposure to TDI. There is no information on the adverse
reproductive or developmental effects of TDI in humans or animals
(U.S. EPA 1994a). IARC lists TDI as a possible human cancer agent.

Urethane Polymers
The TDI in MCUs reacts with a polyol (urethane polymer or co-polymer)
to form the polyurethane finish. Urethane polymers are polyesters and
polyethers. The chemical urethane (ethyl carbamate) is not a
component of polyurethane products. Like the solvents, there are many
kinds of polymers used. The specific polymers used are often trade
secrets and may not be listed on product labels or material safety
data sheets (MSDS). Urethane polymers are usually viscous and have a
low volatility. Since residents do not come into direct contact with
the product, exposure to these chemicals is unlikely.

Based on the findings of this investigation, which included review of
scientific information on MCU ingredients and the inspection at the
Brooklyn apartment building, DOHMH recommends the following:

It is recommended that the use of MCUs be avoided and an alternative
product that contains less volatile and/or less hazardous ingredients
be used. Safer alternatives should always be considered.