When adults hear even mere allegations that children are being sexually abused, they should alert the police.

Recent revelations indicate that this grown-up duty was woefully neglected at The Citadel and Penn State.

But what should adults -- and the authorities -- do when children appear to be nutritionally abused?

What the Cuyahogo County (Ohio) Department of Children and Family Services did on Oct. 19 was remove a little boy from his Cleveland Heights home and put him in foster care.

Well, maybe "little boy" is a bit misleading here. Though only 8 years old, he weighed 218 pounds.

Agency spokeswoman Louise Madigan told The Cleveland Plain Dealer that it had tried for more than a year to help the boy's mother get him into healthier shape. She said the mother wasn't following doctor's orders, so the department took the case to Juvenile Court. Madigan: "This child's problem was so severe that we had to take custody."

The mother, a substitute elementary school teacher now taking vocational classes, disputed that account, telling the Plain Dealer that she had been cooperating with the doctor.

And the mom's lawyer, public defender Sam Amata, pointed out that the child, despite his serious weight problem, is a third-grade honor student who participates in assorted school activities.

Amata fairly asked: "What risk became imminent? When did it become an immediate problem?"

When indeed?

The county agency's argument is that such extreme obesity vastly boosts the potential of a child eventually developing such major diseases as hypertension and diabetes. Its legal action charged the mother with "medical neglect."

That mom countered: "They are trying to make it seem like I am unfit, like I don't love my child. Of course I love him. Of course I want him to lose weight. It's a lifestyle change, and they are trying to make it seem like I am not embracing that. It is very hard, but I am trying."

So how hard a line should government take to assure that kids eat right?

At what weight did that 8-year-old tip the scales so heavily that the Nanny State decided he must be taken away from his mom?

Should government officials also monitor other aspects of parental performance -- and launch child-custody cases -- to assure that kids get enough sleep and exercise, do their homework, don't watch too much TV and don't ride their bikes on hazardous roads?

Think that last rap against a supposedly deficient parent sounds especially far-fetched?

Think again.

On Aug. 25 in Elizabethton, Tenn., a policeman stopped a 10-year-old girl riding her bike home from school because he said she was at too great a risk. The officer also reported the incident to the state's Child Protective Services.

The girl's mother, understandably irate, told tricities.com: "This is a wide street, she's wearing a helmet. I don't allow her to ride in the dark or in inclement weather conditions. She's an avid cyclist."

And: "I'm frustrated that one officer's judgment has left me with an open CPS case, drug me through the media with conflicting information from the police report ... causing chaos and sadness to me and my children."

Creeped out yet?

OK, so it's alarming to know that so many American children are so dangerously overweight.

However, it's also alarming to know that somebody might be closely monitoring not just how fat your kids are but where they ride their bikes.

It's even more alarming to know that a fifth-grader on a one-mile bike ride home from school on a regular street, not a highway, became the object of a "child endangerment" police report to a social-services agency.

And it's downright chilling to know that our increasingly intrusive government's definition of parental "neglect" is expanding at a rapid rate.

So watch out for kids -- on and off their bikes.

But watch out, too, for the relentless advance of Big Brother in the name of "protecting the children."