Home Test Kits for Lead Unreliable, Agency Finds
The U.S. Consumer Product Safety Commission yesterday announced that its evaluation of commonly available kits to test lead levels in paints and other products showed the products are not reliable. The findings are consistent with previous CPSC staff test results. Many of the tests performed using the kits did not detect lead when it was there (false negatives), while some indicated lead was present when it was not (false positives). Of 104 total test results, more than half (56) were false negatives and two were false positives. None of the kits consistently detected lead in products if the lead was covered with a non-leaded coating.
Based on the study, CDC says, consumers should not use lead test kits to evaluate consumer products for potential lead hazards. Two common types of home lead test kits were tested that are based on chemical reactions involving rhodizonate ion or sulfide ion.
Most test kits were developed to detect levels of lead in household paint that are usually much higher than CPSC's regulatory maximum level of 0.06 percent. As a result, staff found that these kits may not be useful for detecting relatively low lead paint concentrations or for detecting lead in other materials, such as metal jewelry or vinyl products. Also, both types of kits may be affected by substances such as iron, tin, or dirt, or by paint colors that can cause the color in the test kit to change or hide the color change, thereby interfering with interpretation of the test results.
As part of the study, CPSC staff also evaluated the use of x-ray fluorescence (XRF) for screening for lead in paint and other products. Twelve of 13 samples were correctly identified as containing lead. The staff notes that this technology, which is generally not available for consumer use, may be of use by a professional inspector for screening for the presence or absence of lead in products, particularly for surface level lead. However, use of the device requires knowledge, training, and consideration of its limitations. For example, XRF detectors have limited depth of penetration -- so for certain applications, such as children's metal jewelry, it is possible for the surface coating to mask the presence of potentially hazardous leaded base metal underneath.
CPSC says testing by a qualified laboratory and trained personnel is the only way to accurately assess the potential risk posed by a consumer product that may contain lead. Consumers can also stay informed of lead-related recalls by signing up for e-mail announcements at www.cpsc.gov.