>examined risk factors; survey years; binary gender; bodyweight; low birthweight; anemia; health insurance coverage; Medicaid/CHIP enrollment; federal Women, Infants, and Children (WIC) supplemental food program enrollment; use of water treatment devices; b age in months; c educational attainment less than 9th grade education; d housing built before 1960 or 1940; e number of cigarettes smoked inside the home per day (1 to 40 or more); f poverty-to-income ratios

I don't see traffic proximity aka urbanicity aka leaded gasoline particulate pollution in there.

Lead plumbing and lead paint are two factors. But there is lead all through the soil and air as well.