I'm assuming it was much like Tuskegee in this respect?
They were exclusively white by design (they enrolled all of the white patients from a particular clinic [0] who were at the targeted point in pregnancy), because the purpose of the experiment was actually to inprove health for other people [1], and to the extent that race might correlate with difference in iron absorption, keeping the study focussed on the population it was intended to help was a goal.
> I'm assuming it was much like Tuskegee in this respect?
Like Tuskegee in that it was all of inhumane, wildly racist, and that the subject population was socially vulnerable, but different in the details of how those factors combined.
[0] whose population served was poor
[1] dangerously radioactive iron was used because it made determining absorption of iron easier, not because the effects of radiation or behavior specific to radioactive iron was being studied.
This is likely true of the radiation experiments, but is not indicated in the article.
It's not, in fact, quite the opposite is true: the subjects were all white, by express design.
What if they were all poor and white, because the study creators didn’t care about poor people, but also were concerned about the clarity of the data for actually improving health for White people, viewing any possible variation introduced by a more representative study population as noise?
(Asking because that is, in fact, how the study was designed; at least, the targeting, the assumption about why it was targeted that way is an inference.)
https://nsarchive2.gwu.edu/radiation/dir/mstreet/commeet/pm0...