How about …
 …Researchers [in a study conducted in mid-
1990s] enticed landlords to recruit 108 families
with healthy children to live in row houses with
varying degrees of lead contamination to
measure the effectiveness of lead-abatement
projects in the city’s poor areas. The parents say
they didn’t know the row houses had lead paint,
and were told too late by the researchers that
their children were being put at risk.
» Boston Globe (9/3/2001, p. 1)