The recipe for that great marinara sauce says nothing abou adding a pinch of aluminum, and lead is nowhere to be found on the menu for the elegant dinner served on the family's best china.
Yet these and other unannounced ingredients -- copper, iron and plastic coatings -- can find their way into food and then into human beings through pots, pans, plates, microwave crisping sheets and other cooking and serving pieces.
It only makes sense that subjecting metal utensils and ceramic plates to high temperatures, hot liquids, salty or acidic foods and sharp objects will jar loose bits of metal or cause minerals to seep from the abused surfaces.
But what this fact means to human health is another matter. As with so many controversies in health and environmental affairs, easy answers to questions about the safety of cookware and china are not easy to find.
Hard, but not impossible. And the most serious health risks are easily avoided by following a few simple suggestions.
Of all the raw materials used to make utensils and dinnerware, of most concern is lead, which is used widely in the glazes that coat ceramic dinner plates, cups and bowls. And lead can account for a quarter of the weight of a piece of leaded crystal.
Lead poisoning leads to a host of health problems, but the most serious are its effects on the central nervous system. Young children and those yet unborn, the two groups most susceptible to lead poisoning, can suffer slowed mental development, which leads to impaired learning abilities and, in extreme cases, mental retardation.
Government regulations establish how much lead may leach from ceramics into food, and spot tests indicate the majority of dinnerware meets those standards, with imported pieces faring less well than domestic china. But those tests cover an infinitesimal proportion of the 1.2 billion pieces of ceramicware sold yearly in this country, and there is no way to tell simply by looking at a plate whether it is a lead-leacher or not.
If it seems unlikely that so much lead could escape into food to make someone sick, consider the case of Marco Tulio Rey, a Westchester County, N.Y., man who in 1987 complained of severe stomach pains. A blood test revealed unusually high lead levels.
While he was hospitalized for lead poisoning, other members of his family reported that they felt abnormally fatigued and suffered dizziness. Public-health officials eventually traced the cause to a broken jug a friend had brought back from Mexico. The Reys used it to store a fermented bean drink, which had eaten away at the glaze.
The key fact was that the bean drink was acidic. Foods and liquids most likely to cause lead to leach out of a ceramic glaze or crystal are acidic products, such as the bean drink or tomatoes, citrus fruits, apple juice, coffee, wine and vinegar. Hot liquids also can speed up the leaching of lead.
Tests have shown that lead levels in port wine stored in a lead-crystal glass shoot up from 89 parts per billion to 3,518 parts per billion after four months, not such a far-fetched amount of time if port is kept in a crystal decanter. In another study that used port with 33 parts per billion of lead, levels increased to 68 parts after one hour, 81 after two hours, 92 after three hours and 99 parts after four hours, according to Barry Swanson of the food science department at Washington State University.
Because of such results, Ernest Foulkes, an environmental health professor at the University of Cincinnati, advises against using leaded crystal for wine or other alcoholic beverages. In general, he says, ceramic bowls and plates should not be used to store acidic foods.
Since 1969, when a California family suffered acute lead poisoning by drinking orange juice stored in a Mexican ceramic pitcher, the Food and Drug Administration (FDA) has set limits on the amount of lead that glazes may allow to leach into foods.
Over the years, the limits have been tightened, in part because studies have suggested that lower levels of lead than previously thought can cause health problems. Also, lead glazes have become a more important source of exposure as other sources have been shut down. For instance, leaded gasoline, by far the single greatest source of lead exposure in the past, almost has disappeared. Lead solder once was used in cans. Now, almost no cans produced in America are lead-soldered, although imported foods may be packed in lead-soldered cans.
In 1991, the FDA again tightened lead standards for ceramic glazes. The limits vary, depending on the size and type of ceramic piece. The standards are tightest for cups, mugs and pitchers, the items most likely to be used repeatedly or used to hold liquids most likely to cause lead leaching. After holding a vinegar solution for 24 hours, these items can leach no more than 0.5 of a part of lead per million parts of the liquid. That is a drastic reduction from the previous standard, which allowed as many as 5 parts of lead per million.
When the FDA tested 111 lots of domestic ceramics in 1991, all complied with the regulations. The results were not as comforting, though, for imported pieces. Of 9,711 lots tested, 2,529 violated the standard. The FDA says Japan and Britain have good quality-control procedures, but in many countries, especially Mexico, ceramics manufacture is a local, home-based business with few assurances of quality.
It's not simply a matter of inexpensive equals hazardous. Because of excessive lead-leaching, Tiffany and Company recently recalled its made-to-order "Private Stock" china, which was hand-painted in France and had an average price-tag of more than $1,000 for a five-piece place setting. The recall does not apply tothe company's more widely available "Tiffany and Co."-marked china.
Although generally given a clean bill of health by the federal government, domestic china manufacturers have come under fire for not meeting California's standard for lead glazes, which is much as five times stricter than the federal standard. In 1991, California sued 10 leading manufacturers of ceramic dinnerware for selling some china patterns that exceeded the state standard. The suit was settled in January, with the manufacturers agreeing to put warning labels on patterns with lead levels above the California standard and to reduce those lead levels by 50 percent over five years.
But for those particularly concerned about lead, it is not a simple matter of avoiding those makers. Last year, California officials and the Environmental Defense Fund, a national environmental group, released the names of hundreds of china patterns that do not comply with the California standard, including many made by companies that had been sued by that state.
In addition to the tips already mentioned to reduce the chances that lead will escape from ceramicware into food, experts note that old china handed down for generations may be suspect, as are pieces with cracked or corroded glazes. Also, dish-washing and microwaving suspect ceramics will speed up the release of lead.
As for leaded crystal, the FDA suggests that such glassware should not be used to store foods and beverages for extended periods, especially acidic foods. Since lead is particularly damaging to fetuses, this advice is doubly important for pregnant women. The government agency also recommends that babies and children never be fed from leaded crystal, including leaded crystal baby bottles that are sometimes given as gifts for newborns.
Stoneware usually is not glazed with lead, but painted decorations or decals could contain lead. Also, layered-glass dinnerware, such as Corning's Corelle brand, contains little or no lead.
In recent years, aluminum has joined lead as a suspect material. Aluminum has come under scrutiny because high levels have been found in the brains of those who died of Alzheimer's disease.
Although the brain measurements are clear, their meaning is not. The aluminum may be the cause, or one cause, of Alzheimer's. Or, Alzheimer's disease may lead to increased aluminum absorption by the brain. So far, researchers have come down on the side of effect, not cause.
"The membranes in the brain have really quite effective means of preventing toxins from migrating from the blood stream to brain cells," Mr. Foulkes says. "But the changes that take place in the brain because of Alzheimer's may well remove that protection."
Aluminum cookware is an insignificant source of exposure to the mineral, the third most common element on Earth after oxygen and silicon. Soft drinks will cause traces of aluminum to leach out of a can; acidic foods, such as tomatoes, likewise will dissolve tiny amounts of aluminum from the cooking surfaces of pots and pans. But if someone used nothing but aluminum utensils and containers for storing and cooking food, he or she would ingest an estimated 3.5 milligrams of aluminum daily, according to the FDA.
This amount pales when compared with the aluminum in many antacids. One tablet can contain 50 milligrams; up to 20 milligrams may be found in a buffered aspirin. Processed cheese contains an aluminum compound to make it melt easier. A potato packs much more aluminum than a meal cooked in aluminum utensils, according to Dr. Forrest Nielsen of the U.S. Department of Agriculture's Human Nutrition Research Center.
On the other hand, there is no need to increase one's aluminum intake unnecessarily. As with lead-glazed ceramics, highly acidic salty foods -- citrus juices, tomato-based sauces, rhubarb or sauerkraut -- will cause aluminum to leach into foods. So, although it seems fine to cook with aluminum utensils, do not store such foods in aluminum containers. Apart from health considerations, corrosive comestibles will discolor or pit the pot's surface.
Copper pots and pans are valued and attractive additions to a serious chef's kitchen. They are prized because they conduct heat so well, important in preparing finicky sauces and holding precise temperatures. But some foods -- the same acidic and salty products that can cause lead and aluminum to leach -- will react with copper, a toxic metal that can cause nausea, vomiting and diarrhea. Toxicologists recommend that copper utensils be used only if they are lined with tin or stainless steel.
More revolutionary than non-stick coatings was the arrival of the microwave oven. One constant criticism of the oven -- that it did not give food a crispy exterior -- has been answered at least partly by the development of "heat susceptors."
These shiny coatings, which usually come with prepackaged convenience foods, such as pizza, reflect heat onto the food so ** the outside cooks as well as the inside.
But tests by the FDA have found that some of the plastic and adhesive coatings "migrate" into the food. Studies in 1989 detected 5 to 7 parts per million of the plastic and 15 parts per million of the adhesive in sample batches of microwaved french fries.
"Some of our studies suggest a potential problem without finding a problem yet," said FDA spokesman Chris Lecos. "Whether it's sufficient to set a standard or not, we don't know yet."
No such uncertainty clouds the use of stainless steel and cast iron. These tough, durable cooking materials get a clean bill of health, although as with every other type of cookware, storing salty and acidic foods in them can pit their surfaces.
In the case of cast iron, which first was used in cooking utensils 3,000 years ago, a nutritional fringe benefit adds to its appeal. A small amount of iron, an important human nutrient, finds its way into food cooked in cast iron.
Just think: Popeye might not have had to down all that spinach if only he had cooked in iron pots and pans.