Pacifiers have long been subjected to many controversies, including their role in causing ear infections, dental abnormalities and stunting emotional growth in boys. A new study says that a pacifier in baby's mouth could harbor deadly bacteria, fungus and mold, that can lead to various diseases.

Researchers from Oklahoma State University have found that pacifiers even have bacteria that cause inflammation and lead to long-term health complications like cardiovascular diseases, asthma, metabolic syndrome and autoimmune diseases, HealthDay reported.

Dr. Tom Glass from Oklahoma State University and lead author of the study says that pacifiers, like retainers, athletic mouth guards and dentures, have pores in them. These pores with lodged food particles and water make perfect breeding ground for germs to thrive.

Researchers discovered that used pacifiers not only had moderate to high levels of bacteria, but also had the kinds of bacteria that are resistant to commonly used antibiotics.

"After doing the study, I say why take a risk? The key is to recognize that pacifiers can cause illness. In the long run, it may be that what you do now [using a pacifier] may have a lot to do with whether a child ends up developing atherosclerosis or type 2 diabetes," Dr. Glass said to HealthDay.

Glass recommends that parents clean the pacifier regularly with denture-cleaning agent and carry extra pacifiers while travelling so that dropped pacifiers aren't used before a round of thorough cleaning.

Also, pacifiers must be disposed after two weeks of use as older pacifiers are more likely to harbor more germs.

Some experts, however, say that pacifiers may not be as harmful.

"The majority of things you're going to find on a pacifier are things we'll find on our clothes, normal human flora. It's not a reason to demonize pacifiers if people find them useful," said Dr. Ben Hoffman, medical director of the Children's Safety Center at Oregon Health and Science University's Doernbecher Children's Hospital, to HealthDay.

The study is to be presented at American Society for Clinical Pathology annual meeting in Boston.