Sorting out risk is a big task

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By John Bartlit


On July 9, the New Mexico Health Department announced, “New Mexicans have a new Web site to learn how environmental contaminants might affect their health.” The site, www.cdc.gov/ephtracking

was six years in the making, with more yet to do.

This large data-handling project, its value and technical hurdles, were described in the Monitor in this essay of March 1, 2005.

Questions about health and blame intrigue us to no end: “Does pollution in my neighborhood hurt my family’s health? If so, who or what is to blame?”

     Good people from all walks of life puzzle through the clues and find certain answers. Yet, the answers they believe in are miles apart.

     How might we do better? A new approach for New Mexico is an effort called Environmental Public Health Tracking, or “EPHT” for short.

     The work is funded by the U.S. Centers for Disease Control and managed by the New Mexico Department of Health. Some other states have related efforts. The participants are data suppliers, data users and data experts of all kinds. Their employers include agencies, counties, tribal governments and the University of New Mexico.

     The goal is to pull together two kinds of existing data and put them in forms that help supply answers. The two sets of data are the available measurements of pollutant concentrations in the air and water at various monitoring sites and the public health statistics, as kept for that political district. The purpose is to learn what, if any, relationships can be found between the occurrence rate of certain health problems in a district and the levels of some pollutant in that district.

     The idea is simple, the rest is not. The problems begin with the data records. For air and water quality, related data are found in varied formats with a variety of units. On occasion, the data recorded change, because the types of monitors change or their locations change.

     Health data have problems of their own. Public health records begin with licensed doctors, and access to doctors depends on a family’s location and its resources. Furthermore, medical tests improve all the time, which changes the detection and the reports of health disorders.

     Another problem is that people change where they live. So we cannot be certain a person’s disease resulted from anything in the district where it is found and reported.

     Then comes the question of privacy. Health statistics are public information, but the health of an individual is a private matter. The line where statistics end and a person begins is clear, until society tries to draw it. Suppose one case of lung cancer is reported in the district of Outland, population 3,000. This “statistic” is enough for the lunch bunch at the Chat-n-Chew Café to guess at what ails Buddy Mack and the feed store he runs.

     How much privacy is lost when a newspaper reports four lung cancers in Middle Field, with its 25,000 imagined people? Privacy is a murky trail. The EPHT project has a lawyer at the UNM Law School hard at work looking through the laws and court decisions, seeking a useful, legal policy on supplying health data.

     Then there is the other problem with small numbers. With one lung cancer in Outland, should the local risk be judged low, average or high? The story is like figuring whether triplets are scarce or rampant based on having one set in town. It can’t be done.

     With such obstacles in the way, is the project worth the money and effort? The real question is, is there some better way to learn the risks from pollutants in the air and water?

     Knowledge is always hard to sort out. The elusive line between fact and opinion yields but slowly to care and effort.

     Without good data sets, a common way to decide about local health risks and their causes is to poll a set of people and go by the winning opinion. In one setting, this method is called electing policy makers. In another setting, it is a jury trial, and we know what DNA science tells about the record of errors in jury verdicts.

     The problems faced in EPHT do not disappear in any alternative approach. The weaknesses are still at work and, worse yet, they go unnoticed.      

    We face imperfections at every turn, yet we have to move ahead as best we can. The Environmental Public Health Tracking Project builds the data bases that tell how pollutants in the air and water affect health. The data and their value only grow with time.