April 20, 2017 / 12:01 PM / 5 months ago

How Reuters analyzed L.A. child lead testing data

LOS ANGELES, April 20 (Reuters) - The Los Angeles data examined by Reuters offers a granular look at where children have been exposed to dangerous levels of lead in the United States’ most populous county.

The data tracks blood lead level testing results for children from birth to six years old from 2011-2015, aggregated by census tract.

L.A. County shared results for each census tract with at least 100 unique children tested over this period. Most neighborhoods throughout the county are included.

The results show children tested, and those with one or more elevated tests. The data reflects the census tract where children were living when they were screened.

An elevated result is equal to or greater than the CDC’s reference value of 5 micrograms per deciliter. Any result above 4.5 is rounded up to 5 and considered elevated, in keeping with a standard convention for reporting of lead test results.

The CDC used the same convention when it found that 5 percent of children tested in Flint had elevated lead levels during the peak of the city’s water contamination crisis.

The CDC lowered its elevated threshold most recently in 2012, in part to reflect the medical consensus that even low levels of lead exposure cause permanent harm to children.

The agency is considering lowering it again, a move that could lead to more children testing high and expand efforts to remove lead from the environment.

The L.A. County results include both capillary (finger-prick) and venous blood tests. Both have margins of error, although venous tests are considered more accurate and “confirmatory.”

The data has limits. Many children don’t get tested, and results from some cities are excluded. Data from Vernon, Long Beach and Pasadena – each with independent health departments – wasn’t available from the county.

California requires testing for children enrolled in Medicaid at ages one and two, and advises physicians to test some other children, including those living in older housing.

A similar “targeted testing” policy is used in most states, including Michigan, although some states require testing for all children. Elevated blood lead levels are likely more common among children who get screened for the toxin, California officials say.

However, Reuters found that even children with risk factors often aren’t tested, including those living in old housing. And Medicaid paid for screening covering only about one in three enrollees for whom tests were indicated in the state, 2015 billing data showed.

California’s Department of Public Health says comparisons with other areas aren’t warranted. Sources of lead exposure, and tracking of blood tests, can differ between areas.

“Testing results need to be considered in the context of the unique population being tested,” the department said in a statement.

The L.A. data builds upon previous Reuters reporting in California. A report last month documented areas, including parts of Fresno, Oakland and Los Angeles, with worrisome childhood exposure rates. That report was based on testing data from about a fourth of zip codes statewide in 2012, shared earlier by the state’s Department of Public Health. Today’s article is based on a far more comprehensive trove of data for L.A. County, recently obtained by Reuters.

Reporting By Joshua Schneyer

Our Standards:The Thomson Reuters Trust Principles.
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