Monday, February 25, 2002
BY CHARLES L. EHRENFELD
New research is linking exposure to trace metals and other environmental toxins to the development of multiple sclerosis.
Dr. Randolph B. Schiffer, chairman of the Department of Neuropsychiatry at Texas Tech's Health Sciences Center, said consumers might want to think twice about zinc lozenges being sold over the counter to ward off colds and other zinc supplements, unless specifically directed by a physician to take them.
"A lot of people take zinc pills. It's supposed to prevent colds and accelerate healing. But until we know what zinc really does, I would certainly be careful about taking zinc supplements," Schiffer said.
"Taking zinc supplements, unless there is a medical reason, is unwise. We don't know what it does in there."
Schiffer formed his opinion as a result of his participation in recent studies examining the prevalence of multiple sclerosis, a chronic, often disabling disease that attacks the central nervous system.
An autoimmune disorder, multiple sclerosis damages the myelin sheath, the protective material that surrounds nerve fibers in the brain, spinal cord and optic nerves. While not fatal, it leads to life-altering disabilities.
According to the National Multiple Sclerosis Society, an estimated 350,000 Americans have multiple sclerosis, with nearly 200 new cases diagnosed every week. There is no known cure, and its causes have remained a mystery.
However, studies strongly suggest that where a person was born and lived during the first 15 years of his or her life influences the likelihood of developing multiple sclerosis, though researchers do not understand why.
Since the late 1980s, Schiffer has studied the possibility that the presence of trace metals in the environment might affect rates of multiple sclerosis.
More recently, he participated in studies examining the prevalence of multiple sclerosis in people who grew up in two neighborhoods in El Paso from the 1940s through the 1960s and another study that found a possible link between a zinc smelter and a disproportionate number of multiple sclerosis cases in DePue, Ill.
"We're going to have to think about environmental toxins in a different way than before," Schiffer said. "I call it 'nontoxic toxicology.' The notion is that exposure to certain levels of things far below OSHA (Occupational Safety and Health Administration) standards can still cause diseases to appear.
"There are environmental experiences that decide whether people get multiple sclerosis, Parkinson's disease, Alzheimer's disease. The problem is, we don't know what they are yet," he said.
Schiffer said multiple sclerosis is caused, in part, by things in the environment, and it often occurs in clusters. Also, the common element in the clusters studied in El Paso and Illinois was zinc.
The zinc factor
In the Illinois study, which was published in the September/October 2001 issue of Archives of Environmental Health, Schiffer and colleagues from the Illinois Department of Health found a possible link to a zinc smelter that had operated for more than 100 years in DePue, a small town on a river in south central Illinois.
Zinc contamination, along with other trace elements, was found in soil, water and air samples, according to Schiffer.
Most metals and pollutants of all types suppress the immune system, Schiffer said, and most environmental contaminants will make a person more vulnerable to infections or cancer, because those are low immune states.
Schiffer said zinc differs from other trace metals in that it is a hyperimmune metal. That is, in some laboratory situations, the correct concentration of zinc actually will increase immune response and could potentially predispose someone to disease.
The DePue study showed that during a 20-year period from 1970 to 1990 there were an abnormal number of new cases of multiple sclerosis diagnosed in the town of 1,800.
Schiffer said nine cases developed during that period, about triple the number of cases that would be considered typical in a town of that size.
"We did not prove that it was related to zinc exposure, but the pattern is suspicious," said Schiffer, who served as the lead investigator for the study.
In the El Paso Multiple Sclerosis Cluster Investigation, Schiffer assisted investigators from the Texas Department of Health in studying reports of an increased number of cases in people who lived in the Kern Place-Mission Hills area of El Paso during the 1940s through 1960s and in neighboring Smeltertown between 1948 and 1970.
Schiffer said 12 confirmed cases of multiple sclerosis, two possible cases and one person at risk were reported — a twofold increased risk based on national prevalence estimates for the disease.
State epidemiologists began the five-year study in 1997 following a report of the possibility of an unusual number of multiple sclerosis cases among people who lived in the Kern Place-Mission Hills area when they were children.
There also were concerns about environmental conditions in the neighborhood during that time.
Investigators used enrollment records from two neighborhood elementary schools — Mesita and E.B. Jones — to locate people who had lived in the area as children. All identified cases of multiple sclerosis occurred in those who had attended Mesita school.
No cases were reported among former E.B. Jones students, but investigators were unable to locate many of those students. The school and all of Smeltertown were demolished in the early 1970s, while Mesita remains open.
The El Paso study is expected to continue for two more years to look for additional cases of multiple sclerosis.
Scouring the state
The Texas Department of Health also is determining current prevalence estimates for the state and will reassess the El Paso data once those state estimates are available.
Meanwhile, Schiffer is working with the state to examine the prevalence rate of multiple sclerosis in the Lubbock area. Local neurologists are contributing patient records for the study, which began in early 2000, Schiffer said. Data collection should conclude next month.
Schiffer emphasized that while the studies in Illinois and El Paso point to exposure to trace metals, such as zinc and other environmental toxins, as a possible cause for multiple sclerosis, the findings are still speculative.
"There has to be confirming evidence
from other domains, and it takes time," Schiffer said. "That's the story.
It doesn't have an ending yet."
© 2002 - The Lubbock Avalanche-Journal