Consumers want to know if vinegars are safe, but there are no easy answers.
In a tradition dating back to medieval times, growers in Modena, Italy, are deep into the grape harvest, the first step in making their famed balsamic vinegar.
Cooking the trebianno and lambrusco grapes releases rich juice that is then stored in vintage barrels. At least a dozen years of fermentation and evaporation reduces the wine to a sweet, fragrant elixir, the pride of a gastronomic culture.
Thousands of miles away, in California, signs in grocery stores warn shoppers about exposure to a dangerous metal in many balsamic and red wine vinegars. The way they are produced, or perhaps heavy metals in the soil, leaves some vinegars tainted with lead, a potent neurotoxin.
Although the amount of lead in vinegar is small, experts say regularly consuming it may pose a risk, particularly to children. Eating one tablespoon a day of some balsamic or red wine vinegars can raise a young child's lead level by more than 30 percent.
Aged vinegars, favored by gourmets and sometimes costing $100 a bottle, contain more lead than the quicker brewed, less expensive kinds. For three imported varieties tested in 2002, people who eat one tablespoon per day would be exposed to seven to 10 times the maximum daily level of lead set by California.
Eating one tablespoon a day of some aged balsamic or red wine vinegars can raise a young child's lead level by more than 30 percent.
One of the oldest known contaminants in the world, lead can damage people's neurological systems, particularly children's developing brains. Even low levels can reduce a child's IQ or trigger learning and behavioral disorders, scientific studies show. Lead also is a carcinogen, and in adults, it is linked to cardiovascular, kidney and immune system effects.
The heavy metal is so toxic and persistent in the body that there is no known threshold below which adverse effects do not occur, according to the U.S. Centers for Disease Control and Prevention.
Lead exposure in the United States has dropped dramatically in the past two decades because the metal was removed from gasoline and paint. But lead in food continues to be a major route of exposure.
The U.S. Environmental Protection Agency estimates that North Americans ingest 50 micrograms of lead each day through food, beverages and dust. A microgram is a millionth of a gram.
For most children, the biggest risk of lead exposure comes from old, deteriorating house paint and tap water, not from vinegar.
But Bruce Lanphear, a professor of children's environmental health at Simon Fraser University in British Columbia, said even the smallest amounts of lead aren't known to be safe for a child's developing brain.
"So, we should, whenever possible, minimize or eliminate exposure," said Lanphear, an epidemiologist who is one of the leading experts researching the effects of lead on children.
Lead levels in vinegar vary widely
In California, warning signs are posted on store shelves as part of a settlement under a state law, known as Proposition 65, that requires consumers to be notified when products contain chemicals tied to cancer, birth defects or reproductive toxicity.
The signs raise questions about the risk of eating balsamic and balsamic-style vinegars, which are gaining in popularity because of new recipes for salad dressings, sauces and other dishes.
Consumers want to know: How much lead is in vinegar and is it safe for children? But there are no easy answers.
Confusing the matter, some vinegars, even aged ones, don't violate the state lead standard even though the store warnings suggest that they do.
Environmental Health News bought two balsamic vinegars at a store in San Francisco last week and hired an independent laboratory to test them for lead. Both were below the 34 parts per billion that exceeds the state's maximum daily lead level. Elsa Balsamic Vinegar of Modena, sold for $29 and labeled as a 12-year-old vinegar, tested at 22 ppb of lead and Manicardi Aceto Balsamico di Modena, sold for $13 and aged for 10 years, contained 23 ppb, according to Anresco Laboratories in San Francisco.
Lead in food products, however, can vary widely from product to product and from batch to batch, said environmental toxicologist Russ Flegal, who runs a trace metals lab at University of California, Santa Cruz. Vinegars are not regularly tested by any agency.
Environmental Health News asked Paul Mushak, an internationally recognized toxics scientist, to conduct computer modeling of several scenarios of children consuming vinegar.
Children 5 to 7 years old who live in houses free of lead in the air and in the drinking water probably have average lead levels of 2.0 micrograms per deciliter of blood.
Eating one tablespoon a day of the vinegar with the highest lead concentration found in 2002 tests – 307 parts per billion – would raise those children's lead levels 30 percent to 2.6 micrograms per deciliter, Mushak calculated. One tablespoon per day is the U.S. Food and Drug Administration's average serving size, although vinegar industry representatives say that is higher than typical consumption.
Two tablespoons a day would raise the children's lead levels 55 percent to 3.1 micrograms per deciliter.
Lanphear said those small increases "may seem subtle" but "the effect on a population is substantial."
Lead warnings posted on vinegar sold in a California grocery store. (daniel/flickr)
Raising blood levels in U.S. children by just one microgram per deciliter "would result in a large increase in the number of children with learning problems or behavioral problems," such as Attention Deficit Hyperactivity Disorder, Lanphear said.
"The economic cost to society would be in the billions of dollars. That is why it is critical to reduce lead exposure wherever it is found," he said.
In 1991, the CDC set 10 micrograms per deciliter as a guideline for the amount of lead that is toxic and could trigger neurological problems in children. Nearly 310,000 U.S. children younger than six years old exceed that level, according to the CDC.
Raising blood levels in U.S. children by just one microgram per deciliter "would result in a large increase in the number of children with learning problems or behavioral problems," such as Attention Deficit Hyperactivity Disorder, said professor Bruce Lanphear.
But new research suggests that reduced IQs and other neurological effects occur at a much lower level, below 5 micrograms.
In addition, for adults, the risk of death from all causes, cardiovascular disease and cancer increase with lead levels as low as 5 micrograms per deciliter, according to the CDC and National Cancer Institute.
Vinegars are acidic and make the metal fully soluble so it's more easily absorbed into the bloodstream.
"If lead intakes from vinegars can be avoided, they should be as a straight-forward precautionary principle," said Mushak, of PB Associates in Durham, N.C., who has helped the EPA and several other agencies develop health standards for lead.
"That would be especially true if children are already near a toxicity threshold from lead paint or dust or any other sources, and vinegar lead might just be enough to nudge the blood lead to a toxicity risk zone," he said.
Michele Corash, a San Francisco attorney who represents the vinegar industry, said the producers don't do anything to add lead to their products. She said the defendants hired experts who determined that lead in the soils of Modena's grape-growing region made its way into balsamic vinegar.
"Grape juice, wine, they all have trace amounts of minerals that are naturally occurring, including lead," and shouldn't fall under the purview of Prop. 65, Corash said. "Virtually all foods have trace levels of one or many chemicals."
Some toxicologists hypothesize that production and storage -- not the soil -- are the main sources of lead contamination.
"Vinegar lead might just be enough to nudge the blood lead to a toxicity risk zone," said lead expert Paul Mushak.
The aged varieties produced by the traditional method, which involved concentration in wood barrels for at least 12 years, have the highest lead levels.
UC Santa Cruz's metals testing lab, which established the vinegar-testing protocol, is researching the origin of the higher lead levels in the aged balsamics, perhaps from the companies' plumbing, implements, or barrels.
Some vinegars had 8-9 times more lead than recommended
The lawsuit that led to California's warnings began when the Oakland-based Environmental Law Foundation tested some 60 vinegar products in 2002. Forty-seven had lead, all red wine or balsamic red wine vinegars. White vinegars and vinegars made from rice, raspberries or figs didn't have lead levels that would trigger warnings.
Under Prop. 65, the state's maximum allowable daily level for lead is 0.5 micrograms per day. Based on that, the Environmental Law Foundation calculated that vinegars could contain no more than 34 parts per billion. The top three tested in 2002 contained 307 ppb, 276 ppb and 237 ppb. They don't appear to be available for sale now.
The law firm filed suit in 2003 and 2004 against 39 suppliers and retailers, and a San Francisco Superior Court approved a settlement in 2007 requiring warning signs on store shelves.
Those signing the agreement included the big chains of Safeway, Target, Raley's, Ralph's Grocery Co. and Williams-Sonoma, and a dozen suppliers selling under many brand names, such as Trader Joe, Star, Colavita and H. J. Heinz Co.
No Lead Warnings
These vinegars do not violate California's Prop. 65 limits for lead. All were tested by the supplier in 2007, except for Archer Farms, which was tested in 2009:
Barengo Imported Balsamic Vinegar, 6 percent acidity
Acetum Star B Quality Two Leaves Imported Balsamic Vinegar, 6 percent acidity
Best Choice Balsamic Vinegar Imported Balsamic Vinegar, 6 percent acidity
Big Y Balsamic Vinegar Imported Balsamic Vinegar, 6 percent acidity
Excellence Balsamic Vinegar Imported Balsamic Vinegar, 6 percent acidity
Holland House Imported Balsamic Vinegar, 6 percent acidity
Nakano Seasoned Rice Wine Balsamic Blend Vinegar, 4 percent acidity Barengo Red Wine Vinegar, 7.5 per acidity
Albertson's Red Wine Vinegar, 5 percent acidity
Fancifood Red Wine Vinegar, 5 percent acidity
Chef's Review Red Wine Vinegar, 5 percent acidity
Great Value Red Wine Vinegar, 5 percent acidity
Safeway Select Red Wine Vinegar, 5 percent acidity
Western Family Red Wine Vinegar, 5 percent acidity
Four Monks Red Wine Vinegar, 5 percent acidity
Holland House Red Wine Vinegar, 5 percent acidity
Four Monks Domestic Balsamic Vinegar, 6 percent acidity
Four Monks Red Wine Vinegar, 6 percent acidity
S & W Red Wine Vinegar, 6 percent acidity
Western Family Red Wine Vinegar, 6 percent acidity
Acetum 4 Star Quality Imported Balsamic Vinegar, 6 percent
Wegmans Balsamic Vinegar Imported Balsamic Vinegar, 6 percent acidity
Western Family Imported Balsamic Vinegar, 6 percent acidity
Best Choice Imported Balsamic Vinegar, 6 percent acidity
Barengo Balsamic Vinegar Imported Balsamic Vinegar, 6 percent acidity
Albertson's Balsamic Vinegar Imported Balsamic Vinegar, 6 percent acidity
Shaw's Balsamic Vinegar Imported Balsamic Vinegar, 6 percent acidity
Nakano Italian Seasoned Red Wine Vinegar, 6 percent acidity
Four Monks Red Wine Vinegar, 5 percent acidity
FSA Red Wine Vinegar, 5 percent acidity
Chef's Review Red Wine Vinegar, 5 percent acidity
Katy's Kitchen Red Wine Vinegar, 5 percent acidity
Pocahontas Red Wine Vinegar, 5 percent acidity
Sysco Classic Red Wine Vinegar, 5 percent acidity
US Foodservice Red Wine Vinegar, 5 percent acidity
Nugget Red Wine Vinegar, 5 percent acidity
Barengo Balsamic Vinegar, 6 percent acidity
FSA Balsamic Vinegar, 6 percent acidity
Barengo Red Wine Vinegar, 7.5 percent acidity
Unbranded industrial/bulk product Red Wine Vinegar, 10 percent acidity
Four Monks Red Wine Vinegar, 7 percent acidity
Four Monks Premium Burgundy Wine Vinegar, 7 percent acidity
Regina Imported Balsamic Vinegar, 6 percent acidity
Regina Imported Raspberry Balsamic Vinegar, 6 percent acidity
Unbranded industrial/bulk product Red Wine Vinegar, 7 percent acidity
Unbranded industrial/bulk product Cabernet Sauvignon Wine Vinegar, 7 percent acidity
Unbranded industrial/bulk product Imported Balsamic Vinegar, 6 percent acidity
Archer Farms Balsamic Vinegar of Modena
Source: Environmental Law Foundation
Companies can remove the warnings if they provide the environmental law firm with tests showing their products have complied with the lead guideline.
Mizkan Americas, formerly Nakano Foods Inc., did that with 47 formulations of its brand names, including Barengo, Four Monks and Holland House. Archer Farms Balsamic Vinegar of Modena, which is sold at Target, also showed that it had met the led guideline.
One company -- Monari Federzoni's green-labeled Balsamic Vinegar of Modena -- advertises on its grape-festooned green label that it "meets California Proposition 65 safety standards."
The fourth-generation family-operated company makes seven types of wine vinegar in Modena. For the green-labeled balsamic vinegar, aged up to three years, the company has every batch tested, said Irene Suhaka, market manager for Monari Federzoni in Bloomfield, N.J.
"We decided to comply. We don't want to put a warning on our product," Suhaka said.
However, the company's older, more concentrated balsamics probably wouldn't be able to meet Prop. 65, she said.
Although the businesses settled the red wine vinegar suit, they still argue that they should be exempt from Prop. 65 because lead is naturally occurring in soil.
Some suppliers, including Borges USA of Fresno, Calif., which produces the brand sold in Target, complain that grape growers and winemakers have gone untouched even though their products also contain lead.
The vinegar industry lawyers also challenge the consumption figures used to determine whether the products violate the state guideline.
Consumption was based on the Food and Drug Administration's serving size of one tablespoon a day. A CDC study showed that average users of balsamic vinegar consume 1-1/2 tablespoons a day.
Corash said the data overstate use because it's a snapshot over two days, and that the FDA serving size is just designed to provide nutritional information.
But she said a trial could have cost millions of dollars, and suppliers faced pressure from retailers to settle.
There is no funding to investigate whether vinegars on the no-warn shelves comply with the law, said James Wheaton, one of the attorneys who brought the lawsuit.
"Somebody needs to go out and test," said Wheaton, because "the levels can be highly variable over time."
Lead guidelines too lax, experts say
Some scientists say it is time to lower federal and state standards and guidelines for lead, including California's level under Prop. 65, because it is based on 30-year-old science.
Tightening California's maximum allowable level "has come up several times," said Jim Donald, chief of reproductive and ecological toxicology at the Office of Environmental Health Hazard Assessment.
But he said there are no plans yet to do so because the scientists don't have enough information to know where to set it.
In June, the CDC also said it is not lowering its lead guideline below 10 micrograms per deciliter because "any decision to establish a new level of concern would be arbitrary and provide uncertain benefits."
In the 1980s, when California's level was set, technology wasn't even available to test for the amounts of lead found in most people's blood today.
"If we looked at the data now, it [the allowable level] would drop substantially," Donald said. "Now we know that 2 to 3 micrograms per deciliter or even lower are having a discernible effect in children."
Banner photo: Barrels of traditional balsamic vinegar. Credit: This.Usually.Works/flickr