BONNERS FERRY — A leaky connection hose in the boiler system caused a release of polypropylene glycol at Bonners Ferry High School Thursday, April 30.

The leak prompted school administrators to send home office staff that afternoon. BFHS remained closed Monday, May 4 as crews went over the entire system to check for further leaks.

“Polypropylene glycol is not a hazardous chemical but can cause throat and eye irritation with prolonged exposure,” said BFHS Principal Tim Gering. “So as a precaution we decided to close school on Thursday.”

School resumed Tuesday but many teachers are still concerned over the implications and possible health risks of the leak.

Propylene glycol (PG) and the similar polypropylene glycol (PPG) are viscous, colorless, odorless liquids made from oxidized propane gas and water and are generally recognized as safe, according to the US Food and Drug administration.

PPG’s are used as deicers or hydraulic fluids where contact with food or humans may be possible. In comparison to ethylene glycol, which is used as automotive antifreeze, PG is much safer for human contact.

PG is used as an emulsifier, surfactant and solvent in many food and tobacco products,

pharmaceuticals, perfumes and other cosmetics — it is a main ingredient in some hand sanitizers, shampoos and laundry detergents for example, as well as the primary ingredient in paintballs. It is also used as the “smoke fluid” in artificial smoke machines.

Over the weekend, crews came in to clean up the spill, Gering said.

“In order to make completely sure the building was safe for everyone we called Avista and a professional heating company to double check the building,” Gering said.

“This was not able to be completed until Monday, May 4 so the high school was closed on Monday. Avista and the heating company gave us the all clear so we were able to return to school on Tuesday.”

Supt. Richard Conley said the leak was not in the piping but in a connection hose, but to be safe crews were asked to check out the entire system for leaks before giving the all-clear.

The district intends to replace the part at fault with upgraded braided hoses to help prevent future leakage, he said.

Some teachers have reported headaches or nausea, but according to the Agency for Toxic Substances and Disease Registry (www.atsdr.cdc.gov), health effects relating to PG exposure are low.

The material Safety Data Sheet on Noble NOBURST lists potential health effects as follows:

Inhalation: No significant signs or symptoms indicative of any adverse health hazard are expected to occur as a result of inhalation exposure.

Eye Contact: May cause minor eye irritation.

Skin Absorption: No significant signs or symptoms indicative of any health hazard are expected to occur as a result of skin absorption exposure.

Skin Irritation: No significant signs or symptoms indicative of any adverse health hazard are expected to occur as a result of skin exposure.

Special Health Effects: This material or its emissions may aggravate pre-existing eye disease.

A full copy of the Material Safety Data Sheet (MSDS) can be found at: noblecompany.com/storage/docs/resources/MSDS-NOBURST-100.pdf