Childhood lead exposure is costing developing countries $992 billion annually due to reductions in IQs and earning potential, according to a new study published today.

The report by New York University researchers is the first to calculate the economic cost of children exposed to lead in Africa, Asia, Latin America and other developing regions. The researchers found that, despite major declines in exposure in the United States and Europe, lead is still harming brains and bottom lines in poorer regions around the world.

The toxic metal is annually taking a 1.2 percent chunk out of the entire world’s gross domestic product, according to the new report.

“Childhood lead exposure represents a major opportunity lost,” said Dr. Leonardo Trasande, a professor at New York University School of Medicine and senior author of the study published online in Environmental Health Perspectives. “Prevention may actually accelerate economic development, which is critically needed in these countries.”

Low levels of lead affect children’s IQs, their ability to pay attention and how well they do in school. It also has been linked to violent and antisocial behavior.

The researchers found that Africa’s economy is harmed the most, with annual economic losses estimated at $137.7 billion, or 4 percent of its gross domestic product – a number that represents a country’s economic output and financial health. Lead exposures cause annual estimated economic losses of $142.3 billion in Latin America, which is 2 percent of its gross domestic product, and $699.9 billion in Asia, which is 1.88 percent of its gross domestic product.

By comparison, economic losses from lead exposure were estimated at $50.9 billion and $55 billion for the United States and Europe.

Trasande and a colleague estimated blood lead levels for children under 5 years old in developing countries. They used previous research to determine how much lead levels would reduce IQ points in the population, and then how much their earnings would drop.

Information about children in many countries is spotty, so the researchers had to estimate exposure, which is a limit of the study, said Dr. Bruce Lanphear, a professor of children's environmental health at Simon Fraser University who is a leading researcher on child lead exposure. He did not participate in the new study.

But the dollar amount is likely conservative, Lanphear said.

“They didn’t look at things like criminal behavior, cardiovascular problems. They focused primarily on children’s intellectual ability,” he said. “The study probably quite substantially underestimates lead’s effect on IQ and GDP (gross domestic product).”

Lead exposure in the United States has rapidly declined since the 1970s, largely due to the phase-out of lead in gasoline. In the 1970s, about 88 percent of kids 5 years old or younger had excessive blood lead levels (greater than 10 micrograms per deciliter of blood), according to the U.S. Environmental Protection Agency.

In 2011, about 5.8 percent of U.S. kids had excessive blood lead levels. This dramatic decrease is in spite of the Centers for Disease Control and Prevention cutting its lead guideline in half, to 5 micrograms per deciliter of blood, last October in response to mounting scientific evidence that low levels can harm children’s developing brains.

Similar trends have occurred in Europe.

But worldwide lead consumption has risen, from about 4.7 million tons in 1970 to 7.1 million tons in 2004, according to a 2010 United Nations report. The increase is largely driven by demand for lead batteries, according to the report.

“There are only a few countries using leaded gasoline, so the majority of the exposures are from lead-based paint, lead battery production and hazardous waste sites,” Trasande said.

As many countries become increasingly industrialized, some, particularly in Africa, have seen spikes in lead exposure over the past three or four decades.

The researchers did not include mild retardation resulting from lead exposure, which is a big problem in Sub-Saharan Africa and parts of Asia, said Ken Jaffe, president and executive director of the International Child Resource Institute, a nonprofit organization that works on children issues around the world.

Jaffe also said it’s hard to estimate IQ point losses without taking into account the state of schools in some of these countries.

“Schools in many countries with high incidences of lead also have poor schools that can be highly abusive to children,” Jaffe said. “I’ve seen schools in Ghana and Zimbabwe where children are beaten for the wrong answer – even in preschool. There are very high dropout rates.”

But, as investors increasingly look to developing countries, putting a dollar amount on environmental exposures could hasten change, Jaffe said.

Previous studies also have looked at economic costs of lead exposure. Every dollar invested in lead paint control results in a $17 to $220 return, according to a 2009 study. Reduced lead exposure in the United States since 1976 has resulted in a $110 billion to $319 billion economic benefit due to higher IQs and worker productivity, according to a 2002 CDC study.

“We’re basically pitting the health of our children versus economic health,” Lanphear said. “Until we can prove it’s cost beneficial to protect kids we won’t do it. It’s really a strange thing for a species to do.”

This article originally ran at Environmental Health News, a news source published by Environmental Health Sciences, a nonprofit media company.