Evaluating Home Lead Tests
Many home lead test kits consist of chemically treated swabs that change color upon contact with lead. Rhodizonate and sulfide are two of the most common ions used in home test kits. When lead reacts with rhodizonate-coated swabs, they turn red or pink, and sulfide will become brown or black.
The reliability of home lead tests has come into question in recent years. In 2007, the Consumer Product Safety Commission (CPSC) tested 300 different home kits and found that more than half of them produced false negatives, or not accurately detecting the presence of lead. According to the study, if a lead-tainted object was covered with a nonlead based coating, the kits couldn't successfully identify the metal [source: CPSC]. Also, the time required for the swab to change colors ranged from a few minutes to a few hours, which could confuse some users. Consequently, the commission recommended that consumers rely on professional in-home lead testing services.
On a more positive note, the commission found a 92 percent success rate with X-ray fluorescence (XRF) screenings of lead-tainted surfaces [source: CPSC]. XRF evaluates the electron activity of elements in test areas in the presence of radiation. The radiation will ionize atoms by causing them to release low-energy electrons, which are then replaced in their orbital by higher-energy electrons [source: Wirth and Barth]. Depending on the wavelength, the energy emitted from the ionization process, the scanner can detect the element, such as lead, that it came from. However, XRF technology isn't generally available to the public, and it's used primarily by professional lead testers [source: CPSC].
The Environmental Protection Agency (EPA) agrees with the CPSC's findings. It advises people to consider professional testing when moving into houses built before 1978. Professional services will examine all of the painted surfaces in a house to determine whether and where any lead-based paint is present [source: EPA]. Beyond that, it's the responsibility of the home owner to decide the optimal method for removing it.
Getting rid of lead-based paint in the home is also better left to experts as well. Burning or sanding surfaces covered in lead-based paint can convert lead particles to gas and fine dust, which can be inhaled. Starting in April 2010, all contractors dealing with lead-based-paint-covered surfaces or removing lead-based paint must adhere to federally mandated lead safety guidelines in private homes, daycare facilities and schools built before 1978.
Related HowStuffWorks Articles
- Environmental Protection Agency. "Lead in Your Home: A Parent's Reference Guide." June 1998. (March 27, 2009)http://www.epa.gov/lead/pubs/leadrev.pdf
- Environmental Protection Agency. "New Requirement to Protect Children from Lead-Based Paint Hazards." March 31, 2008. (March 27, 2009)http://yosemite.epa.gov/opa/admpress.nsf/eeffe922a687433c85257359003f5340/5fc0577fb1a6df5a8525741d006366a2!OpenDocument
- Consumer Product Safety Commission. "CPSC Staff Study: Home Lead Test Kits Unreliable." Oct. 22, 2007. (March 27, 2009)http://www.cpsc.gov/cpscpub/prerel/prhtml08/08038.html
- Consumer Reports. "Testing the test kits." December 2007. (March 27, 2009)http://www.consumerreports.org/cro/babies-kids/child-safety/indoors/kids-and-lead/lead-in-childrens-products-12-07/testing-the-test-kits/testing-the-test-kits.htm
- Haupt, Angela. "It's Banned but Not Gone: Lead Paint Is Still a Danger." USA Today. Sept. 7, 2007. (March 27, 2008)http://www.usatoday.com/news/health/2007-08-28-lead-paint_N.htm
- National Institutes of Health. "Lead poisoning." MedlinePlus Medical Encyclopedia. Updated April 19, 2007. (March 27, 2009)http://www.nlm.nih.gov/medlineplus/ency/article/002473.htm
- Wirth, Karl and Barth, Andy. "X-Ray Fluorescence (XRF)." Science Education Resource Center. Carleton College. (March 31, 2009)http://serc.carleton.edu/research_education/geochemsheets/techniques/XRF.html