BOSTON (Reuters) - A western Massachusetts toddler died over the weekend after suffocating while undergoing a home treatment for head lice involving mayonnaise and a plastic bag, police said on Thursday.

Police in Springfield, about 90 miles west of Boston, responded to the 18-month-old girl's home at about 3 p.m. on Saturday after receiving a 911 call that a child was not breathing, said department spokesman Sergeant John Delaney. Officers found an adult administering CPR to the child, but medical personnel determined that the young girl had been dead for some time, he said.

The family had put the child to bed on Friday night with mayonnaise and a plastic bag on her scalp in an attempt to treat head lice, he said. As the infant slept, the bag apparently covered her face, suffocating her.

"This is a very sad incident," Delaney said.

No charges have been filed, but the incident is under investigation by local and state officials.

There is little data on whether home lice treatments involving fats are effective, according to the Massachusetts Department of Health. The department recommends using prescription and non-prescription medical shampoos.

(Refiles to clarify location to western instead of central Massachusetts)

(Reporting by Elizabeth Barber; Editing by Scott Malone and Mohammad Zargham)