Polymethylene polyphenylene isocyanate (PPI), is a

polyurea Polyurea is a type of elastomer that is derived from the reaction product of an isocyanate component and an amine component. The isocyanate can be aromatic or aliphatic in nature. It can be monomer, polymer, or any variant reaction of isocyanate ...

-based

polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...

derived from

isocyanate In organic chemistry, isocyanate is the functional group with the formula . Organic compounds that contain an isocyanate group are referred to as isocyanates. An organic compound with two isocyanate groups is known as a diisocyanate. Diisocyan ...

monomers A monomer ( ; ''wikt:mono-, mono-'', "one" + ''wikt:-mer, -mer'', "part") is a molecule that can chemical reaction, react together with other monomer molecules to form a larger polymer chain or two- or three-dimensional network in a process called ...

that is used in some glues, aerosol foams, plastics, paint and household products. PPI is listed as a "hazardous agent" by the

National Institutes of Health The National Institutes of Health (NIH) is the primary agency of the United States government responsible for biomedical and public health research. It was founded in 1887 and is part of the United States Department of Health and Human Service ...

because it irritates skin and breathing passages at high concentrations. Some painters exposed to PPI and related

chemicals have developed

occupational asthma Occupational asthma is new onset asthma or the recurrence of previously quiescent asthma directly caused by exposure to an agent at workplace. It is an occupational lung disease and a type of work-related asthma. Agents that can induce occupationa ...

. In chronic toxicity tests, mice exposed to low levels of PPI developed no side effects. Only those mice exposed to the two highest concentrations developed any lung symptoms. The two highest doses used in this study were 1.0 and 6.0 mg per cubic meter for 6 hours each day, 5 days each week for 2 years. The duration-adjusted exposure levels for these two high concentrations are equivalent to 11 ppb and 70 ppb, 24 hours/day for two years.

References

Organic polymers {{polymer-stub