Infant sleep white noise machines are capable of producing hazardous sound levels that may be damaging to infant hearing and auditory development, according to a study led by The Hospital for Sick Children (SickKids).

The recommended safe exposure to noise for infants in hospital nurseries and neonatal intensive care units is a 50-decibel equivalent noise level over 1 hour, according to SickKids. Researchers tested 14 infant sleep machines at their maximum operating volume at three distances: at 30 cm to simulate being in the crib or on the rail, 100 cm to simulate placement beside the crib, and across the room at 200 cm distance from the baby.

The study showed that all of the 14 machines tested exceeded the recommended limits. Even when placed across the room at 200 cm, 93% of the machines exceeded the limit. It is assumed that parents leave the machines on for much longer than the recommended 1 hour, usually for hours at a time while the baby is sleeping.

Dr Blake Papsin, principal investigator of the study and otolaryngologist-in-chief at SickKids, says in a release: “We know that parents are trying to do what’s best for their babies and their sleep, so we hope this study informs the public about the potential harms, and educates them on appropriate use of the machine.”

Papsin and his team recommend the machine is placed as far away from the infant as possible, at a low volume, and for a short duration of time. The researchers also say that music rather than pure white noise is better for infants because it varies in frequency and intensity over time.

The study recommends that policies are created for manufacturers. These include limiting the maximum output level, placing warning labels about noise-induced hearing loss, and requiring manufacturers to include a mandatory timer with auto shut-off.

The study is published in the March 3 online edition of Pediatrics.