ATLANTA (AP) - Childhood rickets - a bone-softening disease that had become so rare the government stopped keeping statistics on it - is making a comeback, in part because some youngsters are not getting enough sunlight, health officials say.

Rickets, a vitamin D deficiency that causes bones to soften and bend and often results in bowlegs, was once a major health problem. The addition of vitamin D to milk in the 1930s virtually eliminated the disease.

But health officials said Thursday that health departments across the country are seeing a resurgence.

The government attributes the comeback to the popularity of milk substitutes like soy that lack certain nutrients; the failure to supplement breast milk with vitamin D; and a lack of childhood exposure to sunlight. Sunlight stimulates the body to produce vitamin D.

The resurgence has been seen particularly among children breast-fed by black mothers. Dark-skinned people absorb less sunlight.

``It's something people have become lax about,'' said Dr. Norman Carvalho of Children's Healthcare of Atlanta, a children's hospital. ``We've been living under the assumption that rickets doesn't occur anymore. But there's a definite increase in the number of cases we're seeing. It seems to be a trend.''

Carvalho led a Georgia study of malnutrition in children that appears in the April issue of the journal Pediatrics.

The 1997-99 study concluded that about one in 200,000 children in Georgia is hospitalized with rickets. But Carvalho cautioned that the rate is probably higher because the study was conducted in the South, where children may get more sun, and because there is no national reporting system.

The study offered no overall national numbers, and there are no earlier figures with which they can be compared.

Among the study's conclusions: Children are not getting enough vitamin D because their parents are keeping them indoors more, leaving them at day-care centers or trying to protect them from skin cancer.

``Parents are working long hours,'' Carvalho said. ``Parents are coming home after dark, and their children are only getting out in the sunlight over the weekends.''

The renewed concern over rickets poses a dilemma for health officials, who have long urged parents to put sunscreen on their children to protect them from ultraviolet rays - which cause skin cancer but also produce vitamin D.

``We really can't promote increased sun exposure for children,'' said Kay Tomashek, an epidemiologist at the Centers for Disease Control and Prevention. ``So it's so important for parents to discuss with physicians the child's nutrition needs.''

That includes being more careful about milk substitutes, which are growing more popular among health-conscious Americans, vegetarians and people with allergies. Some soy milk products do not have sufficient vitamin D for toddlers, and some rice-based milks do not have enough protein.

The CDC also urged doctors to be more vigilant about telling pregnant women to make sure their children get enough vitamin D.

Health officials also said they are studying ways to improve tracking of rickets nationwide.

``It's a lack of awareness,'' Carvalho said. ``A lot of physicians have never seen a case of rickets. They may not even recognize it. People are just not familiar with these conditions anymore.''

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