the Causes of a Mysterious Disease
the Causes of a Mysterious Disease
McBroom, Public Affairs
The large grant will more than double the size of the study from 150 to 400 children and from the Bay Area to all of Central California, making it possible for the first time to evaluate this fatal blood cancer's many potential causes -- pollution, diet, genes, infections and even electric/magnetic fields.
In 90 percent of cases, the cause of leukemia in children remains unknown.
"It's unusual to know so little about the cause of a disease," said Patricia Buffler, chief investigator for the study and former dean of the School of Public Health. "But childhood leukemia is still relatively rare, and you need a large study population to detect low-level associations."
The issue of chemical pollution is a powerful one for communities like Woburn, Mass., where a polluted water supply was believed to have given several children leukemia. This true-life story is depicted in the current movie, "A Civil Action," starring John Travolta.
Eight families whose children were sick sued the corporations they thought responsible and won their case. But there was no proof that the chemicals had caused the disease, said Buffler, who was involved in the Woburn case as an epidemiologist.
"The people of Woburn won eventually; yet we could not answer their questions," said Buffler.
She said that Woburn and hundreds of other cases like it have motivated her to undertake this very large study.
"Otherwise, why would we go to so much trouble?" she asked. "All too often, you can't ascertain causes by investigating a few cases in a cluster. You have to study an entire population, and that is what we are doing."
Buffler said that every child diagnosed with leukemia in one of eight or more hospitals that together serve 35 California counties will be enrolled in the study. Each child will be matched with two other healthy children for a total of 1,200 subjects.
In every case, the child's environment and that of his or her parents will be evaluated in excruciating detail.
Researchers will visit the home, collect information on diet, including the mother's prenatal diet, take dust swipes from the child's bedroom and install a meter to measure electric and magnetic fields. They will identify chemicals used around the house and take a medical history of infections. They also will evaluate the parents' workplaces for chemicals and analyze the child's and the mother's blood for genetic susceptibility and immune function.
When the first codes in the study are broken in the spring of the year 2000, "we will be able to say that we see, or we don't see, an association with environmental chemicals," said Buffler. "Hopefully, we will be able to provide either reassurance or advice in terms of how to take protective action."
The first results next year will reflect the findings of the 150 children currently in the study; findings on the full 400 will be available in the year 2004, Buffler said.
She and her team will evaluate five different theories concerning the causes of leukemia: (1) that a deficiency in certain micronutrients such as folic acid increases the risk; (2) that the age at which children first contract some common infectious diseases affects the later appearance of leukemia; (3) that inborn genetic susceptibility is a contributing cause; (4) that household or workplace chemicals lead to the blood cancer; and (5) that residential exposure to electric and magnetic fields increases the risk of developing the disease.
Hospitals that diagnose virtually all leukemia cases in the 35 counties will be involved in the study. They include Children's Hospital in Oakland; Kaiser Hospitals in Oakland, San Francisco and Sacramento; UCSF Medical School Hospital; Stanford Packard Children's Hospital; UC Davis Medical School Hospital; and Valley Children's Hospital in Fresno.
Buffler said the addition of hospitals in California's Central Valley will increase the number of cases in which agricultural pesticides might play a role.
Each child born in California and diagnosed with leukemia will be matched with an age mate born in California at nearly the same time. He or she also will be matched with a friend so that researchers can compare the three subjects -- one with leukemia and two without -- on the basis of geographical region and socio-economic status.
"We are going to find out as much as we can regarding the causes of leukemia in children," said Buffler. "This is a disease you want to prevent."