Exposure to the chemicals in Moisture Cure Urethane (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, 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.

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.