I read a report, I think on this forum some time back, that was about cockroach infestations causing asthma in children.
I'm pretty sure you have found the answer.
Why More Black Kids Have Asthma:
http://www.respiratoryreviews.com/jul00/rr_jul00_asthmakids.html
Two Quotes:
The researchers did not find racial differences when testing for sensitization to major indoor allergens, including cockroaches. However, they did find that black children were more likely than white children to be sensitized to ragweed and grass. These findings support the hypothesis that black children may be predisposed to asthma.
Poverty isn't the only reason black children have greater asthma morbidity and mortality than white children do. Physiologic differences--specifically, reduced lung function and higher immunoglobulin E (IgE) levels--may contribute to increased asthma severity in black children.
That was the finding of researchers who studied 569 children age 6 to 8 years, 14% of whom were black.[1] "Our study was unique because the African American children were from a middle class suburban area," lead author Christine Joseph, PhD, told RESPIRATORY REVIEWS. Black children in previous pediatric asthma studies typically came from poor urban areas.
Where did Robert Kennedy obtain his research??
Plus ... This stuff all boils down to less housecleaning being done than was the case 20 or 30 years ago. Fewer stay at home Moms = dirtier houses.