不定项选择题 How many children in the world have been exposed to dangerous levels of lead?
That's a pressing question that has had no definitive answer until now. About 1 in 3 children have been exposed to lead at levels shown to damage their health and cognitive development, according to a groundbreaking report that is the first to document the problem globally.
The report, produced by UNICEF in partnership with Pure Earth, a global nonprofit that tackles toxic pollution in poor communities, “is the first report of its kind and it's important,” says KatarzynaKordas, an environmental epidemiologist at the University of Buffalo who studies the effects of toxic metals exposures in children.
The new report finds that some 800 million children worldwide have blood lead levels at or above 5 micrograms per deciliter—a level considered cause for intervention by the Centers for Disease Control and Prevention. Among other harms, lead exposure at that level has been linked to lasting decreases in cognition, including a 3 - to - 5 point drop in scores on intelligence tests “We're talking about a massive problem that has ripple effects, obviously, for the kids, but for society at large,” Kordas says.
Indeed, Kordas says one of the strengths of the new report is that it highlights not only the health consequences of lead exposure but also the economic ones. The report cites one analysis that found that over the lifetime of affected people, childhood lead exposure could result in a loss of nearly $1 trillion in earnings in lower and middle - income countries in Africa, Asia, Latin America and the Caribbean. That kind of economic argument may help to add a sense of urgency in countries where combating childhood lead exposure has not been prioritized.
Lead exposure is particularly dangerous to children under five, whose bodies absorb lead much more efficiently than adults and are at greatest risk of suffering lifelong physical and cognitive damage, the report notes. Childhood lead exposure has also been linked to aggression, hyperactivity and other behavioral problems, notes Joseph Graziano, a professor of environmental health sciences and pharmacology at Columbia University and an expert on lead poisoning in children.
“This has been decades' long silent epidemic that has really deprived generations of children of their full capabilities and their full economic potential,” Graziano says.
While exposure to elevated levels of lead continues to be a problem in parts of the U.S. like Flint, Mich., Graziano says “the Western world has taken it on head on.” As the new report notes, blood lead levels in high - income countries have decreased dramatically since lead in gasoline and paint was phased out, but they remain “dangerously high” in lower - and middle - income countries. Most of the children affected by lead exposure live in Africa and Asia, though many live in Central and South America and Eastern Europe, according to the report.
What does Joseph Graziano say about lead exposure? ( )

A It is associated with a drop in IQ test scores.

B It limits children's creative and economic potential.

C It is particularly serious in Africa.

D It has greater effect on children than on adults.