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. 2020 Sep 23;128(9):097005. doi: 10.1289/EHP6552

Figure 1.

Figure 1 is a flow chart, having three steps, namely, Identify Universe of Studies, Identify Studies Most Pertinent for Health Impact Model, and Identify Studies with Continuous Concentration–Response Function. Step 1: Identify Universe of Studies: Database Searched: PubMed on 14 May 2018 Search String: ((lead [Medical Subject Headings Terms] OR Lead OR “bone lead” OR “tibia lead” OR “patella lead” OR “blood lead”) AND ((Cardiovascular Diseases [Medical Subject Headings Terms] AND mortality) OR (cardiovascular disease mortality) OR (Cardiovascular Diseases mortality) OR (cardiovascular mortality)) AND (“1 September 2011”[Date - Publication]: “3000” [Date - Publication])) (lowercase italic n equals 139) which excludes 131 titles, including Not conducted in humans, No evaluation of lead exposure, and No evaluation of cardiovascular outcomes and leads to Supplemental Literature Search Abstract Review (lowercase italic n equals 8), with 1 abstract removed under No evaluation of lead and cardiovascular disease mortality in adults leads to Unique Studies in Environmental Protection Agency Integrated Science Assessments and or National Toxicology Program Monograph (lowercase italic n equals 8) and Unique Studies from Supplemental Literature Search (lowercase italic n equals 7) leads to 15 Studies on Lead Exposure or Cardiovascular Diseases Mortality Data Identified. Step 2: Identify Studies Most Pertinent for Health Impact Model: 15 Studies on Lead Exposure or Cardiovascular Diseases Mortality Data Identified excludes 10 studies, including B L L greater than 5 micrograms per deciliter and Not Representative of General United States population leads to 5 studies included, namely, Menke and others (2006), Schober and others (2006), and Aoki and others (2006), Lanphear and others (2018), and Ruiz-Hernandez and others (2017). Step 3: Identify Studies with Continuous Concentration–response Function: 5 studies included, namely, Menke and others (2006), Schober and others (2006), and Aoki and others (2006), Lanphear and others (2018), and Ruiz-Hernandez and others (2017) excludes 1 Tier 2 study, namely, Schober and others (2006), then leads to 4 Tier 1 Studies, namely, Menke and others (2006), Aoki and others (2016), Ruiz-Hernandez and others (2017), and Lanphear and others (2018).

Overview of process to identify the most useful studies for developing a health impact model. Note: BLL, blood lead level; CVD, cardiovascular disease; EPA, Environmental Protection Agency; HIM, health impact model; ISA, Integrated Science Assessment; NTP, National Toxicology Program; Pb, lead.