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. 2021 Jul 12;129(7):076002. doi: 10.1289/EHP7381

Figure 3.

Figure 3 is a flowchart titled Database Searches (2013 to 2021) that has five steps. Step 1: A literature search identified 8223 records from PubMed, 6558 records from Web of Science, 4965 records from TOXLINE, 215 Toxic Substances Control Act Test Submissions records, and 138 records identified through additional search strategies, for a total of 17763 records after deduplication. Step 2: Of the 17763 records after deduplication, 5067 were excluded by an electronic screen, leading to 12696 records for title and abstract screening. Step 3: Of the 12696 records for title and abstract screening, 420 were included for full text screening and 12276 were excluded. The excluded records consisted of 12062 records that were not relevant to the populations, exposures, comparators, and outcomes criteria; and 214 records that were written in a foreign language, abstract-only, or did not have full text available. Step 4: Of the 420 records for full text screening, 125 records (115 distinct references) were included as meeting populations, exposures, comparators, and outcomes criteria, including 36 human health effect study records (35 distinct references), 78 animal health effect study records (69 distinct references), and 11 physiologically based pharmacokinetic models; and 295 records were excluded, including 280 records that were not relevant to populations, exposures, comparators, and outcomes criteria; 11 records written in a foreign language or abstract-only; 2 records in which the exposure was not quantified (animal studies); 1 record with unclear route of exposure (animal study); and 1 record which was illegible and unclear if the data was primary. Step 5: There were 675 records tagged as supplemental information during screening, including 426 records with mechanistic information; 227 records with information on absorption, distribution, metabolism, and excretion; 101 records of animal studies with exposure routes other than oral, inhalation, or dermal; and 72 human case reports or case series.

Literature flow diagram for naphthalene. Multiple records were available for some studies, so the box titled “Studies Meeting PECO Criteria” lists both the total number of records and the number of unique studies. The box titled “Tagged as Supplemental” includes mechanistic studies, ADME/toxicokinetic studies, animal studies with exposure routes other than oral or inhalation (e.g., injection studies), and human case reports. Note: ADME, absorption, distribution, metabolism, and excretion; PBPK models, physiologically based pharmacokinetic models; PECO, populations, exposures, comparators, and outcomes; TSCATS, Toxic Substances Control Act Test Submissions; WOS, Web of Science.