Some parents want their children to be tested for aluminum, but there's no agreement on what "normal" levels of the metal are, a new study finds.
Aluminum is everywhere, in the air, soil, water and food. Exposure to high levels—in some workplaces with aluminum dust, for instance—can be toxic. But no one is sure what health effects, if any, everyday exposures might have.
Still, similar to the case with mercury, some parents have concerns that aluminum exposure could have contributed to their children's autism or other developmental disorders.
And they are coming to doctors asking about aluminum testing. Dr. Michelle Zeager, who led the new study, said that questions from parents prompted her and her colleagues to look at how labs define the range of "normal" when it comes to children's aluminum levels.
They found wide variation across the 10 U.S. labs that do such testing.
The central issue is, in part, that different labs use different studies to derive their reference ranges for aluminum, according to Zeager. Beyond that, the studies they use have not included healthy children; instead, studies have mainly focused on adults—and often adults exposed to high levels of aluminum through work, or those on kidney dialysis, which can raise aluminum levels.
"What we found was that even in labs that used the same methodology, there was a wide range in what's called 'normal,'" said Zeager, a pediatrician at Children's Hospital Boston.
When it came to aluminum levels in the blood, for example, one lab defined normal as less than 5.41 micrograms per liter. Another said it should be below 42 mcg/L. The rest of the labs fell in between.
It's important, Zeager said, that parents be aware of all the unknowns when it comes to aluminum.
Not only is the range of "normal" unclear; so are the health effects of relatively low exposures. "We don't know what levels could have effects in kids, or what those effects might be," Zeager said.
Aluminum exposure is unavoidable. Food is the biggest source, with the average U.S. adult ingesting 7 to 9 milligrams of aluminum each day, according to the U.S. Centers for Disease Control and Prevention (CDC).
Other sources include antacids, antiperspirants, cosmetics and buffered aspirin.
However, the CDC says, very little of the aluminum we eat, breathe or put on our skin is absorbed into the bloodstream.
"More research needs to be done in order to establish what's 'normal' (aluminum) in children," Zeager said—adding that large studies of the general population are needed to do that.
The CDC has an ongoing project looking at Americans' blood and urine levels of various environmental chemicals (see 1.usa.gov/c971xg). That study has not yet assessed the range of Americans' aluminum levels, but the metal is on the list for future study, Zeager noted.