Children born to women who are poor, uneducated, black or Latino are more likely than others to be mildly retarded, according to two new controversial studies.
The federally funded studies confirm what many psychologists and social workers have been saying for years: Deprivation and social hardship can stunt human intelligence.But the studies, published Tuesday in the American Journal of Public Health, were attacked by others, who say the conclusions cannot be trusted, because they are racist and lead to discriminatory treatment of minority children.
The studies suggest alarming mental-health implications for the future of the country, said Centers for Disease Control and Prevention director Dr. David Satcher, because there has been an increase both in the number of minority children and in the number of impoverished children of all races and ethnic groups in America.
"As America becomes more diverse," Satcher wrote in an editorial accompanying the studies, "greater efforts need to be directed toward improving access to economic and educational opportunities and removing obstacles such as poor health and the possible effects of discrimination and racism."
Public health policies that focus on improving childhood environments can help overcome these negative effects, he wrote.
"We believe that much of the excess prevalence of mild mental retardation is preventable," Satcher concluded.
Forty years ago, the big risk to children in the United States was infectious disease. Now, troubles affecting overall health - including psychological and learning problems - are the big risk, Satcher said.
Many of the medical causes of severe mental retardation have been identified and eliminated in recent years.
But the social factors found to be linked to mild retardation - defined as IQ scores of 50 to 70, compared to the average of 100 - are worsening, say public health experts.
The studies, one conducted by the National Center for Health Statistics, the other by the CDC, found that:
- Children of poor, minority and poorly educated families scored lower in IQ tests than others, according to the NCHS study.
To a lesser degree, the child's general health and history of birth complications also predict IQ.
- The rate of mental retardation was 80 percent higher in black children than white children - largely because of poverty and other social conditions, the CDC report said.
Julia and Nathan Hare, San Francisco sociologists who have written many books including one on the education of black children, were furious at the study's results.
They say the federal studies have no relevance to reality because they don't explain how the majority of black professionals and leaders - most of whom grew up in segregated poerty but overcame it - joined the ranks of lawyers, doctors and other professionals.
Nathan Hare, who has doctorates in both sociology and psychology, charged that the financing of such studies was a "funding of genocide."
The standardized IQ tests that measure intelligence don't take into account the environment black children of any socioeconomic background grow up in, he said.
"Black children are at least 20 percent smarter than the scores on their tests," Nathan Hare said.
"If they keep preaching that blacks are inferior, people will start to believe it," Julia Hare said.
These two new studies do not resolve the role of "nature or nurture" in IQ, the researchers who conducted the studies said.
Some children may have been born mentally handicapped and were further handicapped by social deprivation. Others may have been born with average IQs that declined as a result of their upbringing, the researchers said.
But they suggested that a rich environment could help overcome innate disadvantage. Reading and talking to children can provide them an early intellectual boost, the researchers said.
"Children of minority status and those living in poverty face difficult challenges related to physical and emotional health, housing, educational and social opportunities, nutrition and general discrimination and racism in American society," concluded Rachel Kramer, lead investigator for the NCHS study.
Poverty increases the chance that children are exposed to the IQ-lowering effects of lead.
And poor mothers are less likely to receive early treatment or medical care for conditions that increase risk of retardation in their children, such as anemia, hypertension, diabetes, renal disease and sickle-cell anemia.