Cleaning methods may be to blame for deadly milk contamination

Dan McDonald

State officials suspect cleaning methods at the Whittier Farms dairy processing plant may have ``unintentionally caused contamination'' of equipment with Listeria, the bacteria that has killed three people and made two others ill since last June.

"It's one of the theories we're looking at,'' Susanne Condon, director of bureau of environmental health, said this afternoon. "There are hoses that are used to spray down areas of the plant.''

Those hoses may have sprayed some of the bacteria from the floor onto equipment in the plant and eventually into the final milk product, said Condon.

The state's findings, released today, do suggest the contamination occurred after the milk was pasteurized, perhaps during the bottling process.

After checking the timing, temperature, and milk flow of the plant's pasteurization equipment, dairy inspectors found the dairy met federal standards, according to the statement from the Department of Public Health.

"The staff also looked at calibration records for the equipment, and there were no problems with the equipment itself - temperature gauges or anything like that like that,'' said Condon.

The Department of Public Health first issued a warning regarding Whittier milk products on Dec. 27, after connecting two deaths and two illnesses to milk from the dairy since June 2006. Earlier this month the death of an elderly Medway man was also linked to the bad milk.

Four of the five cases have been linked to the "A'' strain of Listeria bacteria, said Mary Gilchrist, director of the State Laboratory Institute.

Of the 100 samples taken from the plant in the past few weeks, 12 milk samples and four "environmental samples,'' - swabs taken from the floor, bottle washband, an unwashed bottle, and a drain - have tested positive for different types of Listeria, according to the state. Nine of the 12 positive milk samples were flavored milk featuring such flavors as strawberry, vanilla, chocolate, and coffee.

Eight of the milk samples and one of the environmental samples were contaminated with the "A'' strain of Listeria that is being connected with the three deaths and one illness.

Officials suspect the sugar content of those products encouraged bacteria growth.

``But we haven't tested enough containers to make an absolute determination on that yet,'' said Gilchrist.

The plant will remained closed until the Whittiers can demonstrate they can produce non-contaminated milk, said Condon.

``That bar has not been met yet,'' she said.

She would not say when she thought dairy operations would be able to resume.

Dan McDonald can be reached at 508-490-7475 or at

The MetroWest Daily News