The Dangers of Hypromellose Phthalate

Hypromellose phthalate, which is also known as hydroxypropyl methylcellulose phthalate, is a colorless, odorless white powder. It is used in building materials as a component of tile adhesive, as an ingredient in certain over-the-counter eyedrops, and as an excipient, or nonreactive binding agent, in various pharmaceutical pills.

Toxicity by Ingestion

• Hypromellose phthalate is only toxic at extremely high doses. The LD-50 for lab rats, meaning the dosage at which fifty percent of the test population dies, is over 15 grams per kilogram. A human weighing 120 pounds would need to eat nearly two pounds of the powder to get an equivalent dose.

Contact With Eyes

• Low concentrations of hypromellose phthalate are used in various eye drops, and should actually help to reduce dryness and irritation. The pure, powdered chemical is not corrosive or caustic, but should still be washed from the eyes with clean water if exposure occurs.

Contact With Skin

• Hypromellose phthalate is not known to cause burns or irritation from skin contact, but any powder on bare skin should still be washed with soap and water. If any symptoms occur, contact a doctor.

Fire Hazard

• Hypromellose pthalate in the powdered form can form explosive mixtures with the air. This is only a danger when large amounts of the powder are airborne; the powder itself is not flammable unless mixed with air to form a dust cloud and then exposed to a spark or flame before it settles back to the ground. The same danger exists for many powders, including wheat flour, for example. Because of the large amounts of powder required for an explosion, this is only a danger for industrial-scale use. In these situations, the workplace should be kept clean to minimize dust accumulation.