DEAR DR. BLONZ: I read the ingredient lists on the products I buy, in addition to the Nutrition Facts labels, and stick to whole foods whenever possible. I would like some background information about natural color additives versus artificial ones. -- M.Q., Evanston, Illinois

DEAR M.Q.: The purpose of adding coloring is to make the item more appealing; when it comes to food, we are suckers for good looks. Would there be any consumer interest in gray hot dogs, brownish maraschino cherries or colorless colas, even if these are the actual colors of these processed foods?

Once, food coloring was used unscrupulously to hide the defects of spoiled merchandise. For example, small amounts of copper sulfate, now a known poison, were added to bring pickles to a brighter shade of green, and lead-containing dyes were formerly used to give candies their bright colors. It took the passage of the Federal Pure Food and Drug Act of 1906 to outlaw such practices.

Our brains have a hard time when food colors are wrong. One study demonstrated that volunteers couldn't correctly identify strawberry flavoring when it was tinted green. And in a classic test in the 1970s, people were fed a meal of steak, peas and French fries under lighting that concealed the foods' appearance. When the lights were raised to reveal blue steak, red peas and green French fries, several volunteers became ill despite assurances that the food was wholesome, just tinted.

Artificial colors have come and gone over the years. A notable case involved the 1976 ban of red dye No. 2, a widely used food and cosmetic coloring. Large amounts of the dye -- many times greater than would ever be used in food -- were found to cause cancer in laboratory animals. The ban focused public attention on artificial food dyes, and many companies shifted toward using natural colors.

While the name might suggest differently, natural colors are rarely natural to the foods to which they're added. Instead, they are color-rich chemicals from animal, vegetable or mineral sources. Natural red food coloring, for instance, can be extracted from beets or might come from carmine, a crimson pigment from the shell of a Central American insect. Both are considered "natural" red colors, and they're used in everything from fruit drinks to candy to strawberry ice cream.

Whenever colors are added, it must be indicated on the label, but the terminology for natural colors can be confusing. If a natural color is not "natural" to the food to which it's added, such as beet powder used to tint strawberry yogurt, the food cannot claim to be naturally colored. But since that beet coloring is natural, the yogurt could claim to have no artificial colors.

While there can be rare sensitivities to color additives, they are generally safe, given the small amounts used. There had been early reports about food colorings contributing to behavior issues in children, but these have not stood the test of further research and study. (Check the FDA page answering consumer questions at b.link/t2b2kg.)

It is always best to base our diets on whole foods that don't use color additives; such foods don't need help in the appearance department.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: A recent letter asked about eating corn -- the writer, also from Tulsa, related a fear of eating corn stemming from some "doctor videos" they had seen. You replied that eating corn isn't a problem. I would like to share my experience.

In my teens, in the 1950s, I worked in the Iowa cornfields detasseling corn. Unknown to the average layperson, the fields were full of pesticides and herbicides, primarily DDT, dioxins and others. These chemicals persist in the soil for many years. We ate a lot of sweetcorn and popcorn.

Then in my 60s, I was diagnosed with non-Hodgkin lymphoma. The doctors stated that it is a known scientific fact that non-Hodgkin lymphoma is one of the cancers caused by pesticides and other chemicals used in farming. Consequently, I now only eat organic corn products, and try to stick to organic with other foods whenever possible. Perhaps wise advice for anyone. -- S.W. Tulsa, Oklahoma

DEAR S.W.: My regards for sharing your unfortunate experiences. We have learned much since the 1962 publication of "Silent Spring" by Rachel Carson helped identify and ban DDT and other pesticides. Public concern about pesticides typically focuses on potential dangers from eating the foods grown with their use -- but what about the workers who apply such chemicals? And what of our environment, which becomes the chemicals' final resting place?

America's obsession with perfect-looking produce is one of the key factors behind the continued demand for pesticides. In a report entitled "Alternative Agriculture" (available at b.link/9fz4gr), the National Academy of Sciences detailed how the food industry encourages the use of pesticides solely to maintain high cosmetic standards. Surveys about citrus fruits conducted by Public Voice and by the American Farm Bureau Federation found that, in some cases, over half of pesticides are used for cosmetic reasons, such as preventing minor external blemishes that have nothing to do with the taste or nutrition of the fruit.

Many health experts place the hazards from pesticides well behind other dangers in our food supply, such as bacterial contamination and naturally occurring toxins. They say that the major risks in our food supply are placed there by nature, not technology.

However, numerous unanswered questions remain. For example, there is no practical way of measuring how, or if, an amount of residue deemed safe today might affect your health down the road. We also have no way of judging the effects of residues in combination with each other, or what happens when pesticide exposure occurs in conjunction with other health problems or medications. That may be why, despite assurances, surveys reveal that American consumers continue to be wary.

There are alternatives to the continued use of pesticides. One, as you correctly point out, involves organic agriculture. Organically grown crops, which generally cost more to produce than most conventional foods, are raised without synthetic chemicals, such as pesticides, fertilizers, animal feed additives or growth regulators.

A reasonable bottom line: There's little question that it's better to eat conventionally grown produce than not to eat fruits and vegetables at all. Our produce market is not a hazardous place where we need to fear every bite. Yet this does not justify blind support for the use of unnecessary synthetic pesticides.

We should eat as though our life depends on it, and at the same time, we need to be aware of the environmental impact of our food choices.

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: I mainly use wooden cutting boards when I prepare food, with some plastic boards as backups. The boards are used for trimming meats, chicken and fish, as well as chopping vegetables. I always wash the boards after each use, but is this enough to guarantee safety? -- M.A., Oakland, California

DEAR M.A.: Food is only as clean as the dirtiest surface it touches. As long as a cutting board is carefully cleaned between uses, it should not absorb liquids or trap solids from items cut on it. The material used for cutting boards should be hard, but not so hard as to dull a knife's edge.

A favorite board can become a point of contact between foods, so you must avoid letting it become a microbial breeding ground -- and therefore a potential conduit for food-borne infection. To help prevent cross-contamination, consider using different boards and utensils for plant foods and animal products.

Avoid mixing up tools that have touched raw meat with those that will be used on the prepared dish. Consider designating a bowl or plate to hold items that have touched raw foods, to avoid inadvertently grabbing them for another use. Cooked foods that must sit before serving should rest on a clean surface, along with any clean utensils to be used for plating and serving.

Anyone helping in the kitchen should be aware of what's been on all kitchen surfaces; you would not want potentially contaminated surfaces to come in contact with foods about to be plated or utensils set for use during the meal.

Back to the issue of cutting board materials: Hardwood boards are attractive, but the wood can dry and crack and absorb liquids over time, and food particles can become embedded during cutting. If wood is your choice, you can take steps to help make it a safe surface. First, the item should undergo an initial wash and dry as soon as you bring it home. Next comes the oiling, to help control fluid absorption and prevent drying and cracking. Oils made for this are often mineral-based, but whatever you use, be sure it is clearly labeled as a food-grade cutting board oil. (Edible polyunsaturated seed oils such as corn, soy and canola should be avoided, as these can turn rancid and affect your food.)

After each use -- and especially when animal products are cut -- the board must be cleaned with hot water and dish detergent. A mild disinfectant such as a bleach/water solution can be used; the U.S. Department of Agriculture recommends a solution of 1 teaspoon of bleach per 1 quart of water. Rinse well, and do not put boards away until they are completely dry. Periodic reoiling should be done as needed.

Have separate, easily identifiable boards for cutting meats, both raw and cooked. Consider using one of your hard plastic "backup" boards for raw meats, as they can be easily cleaned in the dishwasher. It is best to discard cutting boards -- of any material -- when they acquire hard-to-clean grooves.

For more on cutting board choices and their safe use, check out the articles from foodsafety.gov (b.link/uv3p8x) and the USDA (b.link/1abgtd).

Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.