The researchers here used a comprehensive analysis of data collected from multiple sources, including the Cleveland tooth enamel data from 1936 to 1993, two different Lake Erie sediment data sets (one collected by faculty from the CWRU geological sciences department), data from the Bureau of Mines and traffic data from the Ohio Bureau of Motor Vehicles.
Because blood tests to determine lead levels were unreliable prior to the mid 1970s, the team used lead levels in the enamel of teeth removed from adults at Cleveland dental clinics to determine their childhood lead exposure.
James A. Lalumandier, chair of the Department of Community Dentistry at CWRU's School of Dental Medicine, obtained teeth, which were removed from for dental reasons. Richard A. Shulze, a former dental student now in private practice, developed the method to extract lead samples from the enamel.
They trimmed the outer layers to reveal lead trapped within the enamel of developing first and second molars. Like trees, teeth grow in layers around the center, Lalumandier said. The enamel layers in first and second molars provide a permanent record of the lead to which the tooth's owner was exposed, with mid-points of lead incorporation at about ages 3 and 7, respectively. The researchers obtained the birthplace, age, sex and race of the owners and wound back the clock.
Chemistry Professor Michael E. Ketterer began the lead analysis at John Carroll University in Cleveland and continued after moving to Northern Arizona University.
Lead levels in the teeth were compared to reliable blood levels taken in the 1980s and 1990s, Lake Erie sediment cores that reflect atmospheric lead levels of the past, as well as leaded gasoline use by year.
Sun and former PhD student Zhong-Fa Zhang, now at the Wistar Institute in Philadelphia, who joined in the study in late 2003, developed and applied modern statistical methods to mine the information and compare d
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Case Western Reserve University