"Two primary channels emerge through which intervention affects antisocial behavior and cognitive outcomes. First, intervention may dramatically reduce the amount of continued childhood exposure to the dangerous neurotoxin by directly reducing exposure risks within the home environment. Second, long-term benefits may occur through improvements in early-life health unrelated to any changes in lead exposure. [11] ...
[11] The elevated BLL intervention package includes treatments previously demonstrated to impact later-life outcomes such as: visits from health workers; increased medical care; nutritional assessments and dietary modifications; and referral to the Special Supplemental, Nutrition Program for Women, Infants, and Children (WIC). Prior research documents long-term benefits from programs similar to each of these elements ..."
Why didn't they control for the other intervention treatments? One where they reduce BLL + other treatments, and one where they didn't reduce BLL but still gave the other treatments?