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Toxins in packaging tests show inconsistent results

A new study assessed the performance of laboratories in measuring the total concentrations of four metals-lead, cadmium, mercury and chromium-in plastics packaging with some surprising results. Four out of the seven laboratories tested reported one or more unacceptable results, with one national lab actually having inaccurate results for five of the eight packaging samples they tested. For the purposes of the survey, a result was considered unacceptable if it varied by more than 25% from the average of all laboratories' results, as well as from an x-ray fluorescent (XRF) analysis.

Fully 16% of laboratory test results for lead and cadmium in packaging samples were "unacceptable" according to the report just released by the Toxics in Packaging Clearinghouse (TPCH). The TPCH believes the underlying issue could lie in how the samples are tested. "Measuring the total concentration of metals requires that the sample be completely dissolved," the TPCH said in a release on the report. "We don't believe that some labs are paying careful enough attention to this critical performance goal, resulting in analytical results that underreport the amount of heavy metals, particularly cadmium and lead, used in packaging."

Only one packaging sample of the 42 analyzed by the seven labs resulted in a 'false negative', where testing indicates that a sample is in compliance with state laws when it in fact is not. False negatives exhibit more of a risk to the public since they could lead a company to believe they are in compliance when they are not.

The TPCH said the goal of its study was to "make sure that labs who provide support services to companies are applying testing methods consistent with the requirements of toxics in packaging laws." Specifically, the TPCH said determining the total concentration of the restricted metals is possible only through complete sample decomposition. "If total sample decomposition is not achieved, the laboratory should state so on the test report, as it strongly impacts the accuracy of the results," TPCH said.

The California Department of Toxic Substances Control (DTSC) contracted with TPCH to perform this round-robin study.  The report, Laboratory Round Robin Test Project: Assessing Performance in Measuring Toxics in Packaging, is available for download on the TPCH website. Nineteen U.S. states have toxics in packaging laws, with 10 of those (California, Connecticut, Illinois, Iowa, Minnesota, New Hampshire, New Jersey, New York, Rhode Island, and Washington) members of the TPCH.

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