The discovery of lead in some city-raised eggs is ruffling feathers among public health experts.
An ongoing study by the New York State Department of Health found eggs raised in urban neighborhood gardens contained levels of lead significantly higher than those seen in store-bought eggs. The lead is thought to come from contaminated soil eaten by city-dwelling chickens.
"Because we feel it's important to reduce lead exposure wherever possible, we encourage chicken keepers to be aware of the potential risks associated with contaminated soil and take measures to minimize those risks, while at the same time recognizing that raising chickens can be a healthy activity," said Henry Spliethoff, a research scientist with the Department's Bureau of Toxic Substance Assessment.
Lead exposure in children is linked to low IQ later in life. And lead poisoning in people of all ages can cause difficulty sleeping, headaches, seizures and even comas. The U.S. Food and Drug Administration has no limit for acceptable lead exposure in eggs, but in 2005 set a limit of 100 parts per billion for candy consumed by children.
Spliethoff and colleague tested 58 eggs raised in community gardens around New York City and found nearly half contained lead levels between 10 and 73 parts per billion. One egg had levels exceeding 100 parts per billion.
"We were encouraged to find that all the eggs had lead levels were below the guidance value except for one," said Spliethoff. "Eggs with lead levels below that guidance value -- even with a fairly egg-heavy diet -- are probably OK."
But some experts say no level of lead in food is safe.
"There's virtually no level at which we can assume lead is not dangerous," said Dr. David Rosner, a professor of sociomedical sciences at Columbia University's Mailman School of Public Health.
Rosner, who co-authored the 2002 book "Deceit and Denial: The Deadly Politics of Industrial Pollution," said lead levels in urban neighborhoods have been "a contentious issue for a very long time."
"The problem is that we've never been willing to confront this issue head on," he said, describing how old buildings with leaded paint were demolished rather than detoxified. "It just continues to haunt us."
Rosner's newest book, "Lead Wars," is set for release in February 2013.
Dr. John Spangler, professor of family and community medicine at Wake Forest School of Medicine in Winston-Salem, N.C., said the finding of lead in city-raised eggs is no surprise given the rampant use of leaded paint until the 1970s.
"This makes perfect sense," he said, adding that the study applies not only to eggs but any community garden where a building once stood. "It's difficult to choose between lead exposure and the health benefits of fresh eggs and vegetables. But if you have a highly contaminated vacant lot, you need to know before you start using it."
While the New York study is ongoing, Spliethoff said urban farmers should be aware of their soil's lead levels and make efforts to minimize their chickens' exposure by building separate chicken runs, putting food in a feeder and laying down extra mulch or soil.
"We feel it's worthwhile for chicken keepers to be aware that chickens do eat soil and if the soil has lead or other contaminants, it can get lead into the eggs," he said.
As for the lead levels seen in city eggs, Spliethoff said they should not discourage people from eating locally raised food.
"The levels are not something to be scared of, but they are something to strive to be below," he said.