The rate of cancer among American children has been rising for decades. Although the reasons remain unclear, many experts suspect the increase may be partly the result of growing exposure to new chemicals in the environment.
That suspicion, though still unproved, is beginning to shape federal research priorities and environmental strategies.
Depending on which types of cancer are counted, and in what age groups among the nation’s youth, the rate of increase has amounted to nearly 1 percent a year, according to the National Cancer Institute.
Over a few decades, that has meant striking double-digit increases.
Childhood cancer is still far less common than cancer in adults, and its very rarity makes it especially hard to discern what might be causing the increase. Its creeping spread has also been masked by better news, as recent medical gains have made it much more likely that a child with cancer will survive.
But childhood cancer, even when its young victims are cured, can inflict wrenching costs on children and their families, whether the toll is measured in financial, emotional or physical terms. Patients can suffer permanently from brain damage, stunted growth or secondary cancers later in life, partly as a result of radiation and chemical therapies.
And today, according to experts in the field, a newborn child faces a risk of about 1 in 600 of contracting cancer by age 10.
In the United States, cancer is diagnosed each year in an estimated 8,000 children younger than 15. Cancer, although it kills fewer children than accidents do, is the most common form of fatal childhood disease, accounting for about 10 percent of all deaths in childhood.
The increases surprise even people who are predisposed to think the worst about the ill effects of chemical pollution.
“I had not realized that the numbers were going up that way,” said Karen Florini, a lawyer specializing in health issues at the Environmental Defense Fund. “I think it indicates a very disturbing trend that we had better get to the bottom of.”
Acute lymphoblastic leukemia in boys and girls increased 27 percent between 1973 and 1990; since then, the rate in boys has declined, but it is still rising in girls. Brain cancer, or glioma, increased nearly 40 percent from 1973 to 1994. These two forms of cancer account for most of the disease in children.
Other forms of cancer, such as the form of bone cancer called osteogenic sarcoma and the kidney cancer known as Wilms’ tumor, also have been rising, although the numbers of cases remain so small that the trends may not be statistically significant.
The increases are big enough that better diagnosis and reporting of the diseases are unlikely to be the principal explanation, experts say; childhood cancer is such a serious ailment that it is usually detected.
Although there are probably many causes for the increases, some experts say, toxins in the air, food, dust, soil and drinking water are prime suspects.
So with the Clinton administration putting a high priority on issues of children’s health and the environment, and with Congress last year overwhelmingly approving new laws taking children’s exposures into account when setting standards for pesticide residues in food and contaminants in drinking water, federal authorities are moving to review the epidemiological data much more closely and to review environmental regulations that may help fight the trend.