DEAR DR. BLONZ: A tomato carton at a local produce market stated that the tomatoes contained a number of "non-tomato ingredients." It listed petrolatum, paraffin, carnauba wax and food-grade mineral oil. The carton also stated that the fruit had been treated with ortho-phenylphenol to inhibit mold. Are these substances in or on the tomatoes, and are they dangerous to eat? -- P.P., Vallejo, California
DEAR P.P.: Petrolatum, paraffin and carnauba are different types of waxes. Produce growers apply waxes to their fruits and vegetables to retain moisture, slow flavor loss, enhance appearance and prevent mold during packing, shipping and selling. Petrolatum and paraffin are byproducts of petroleum (oil). Carnauba, which comes from the wax palm of Brazil, is also used in car wax.
Waxes are applied to a wide variety of produce, including tomatoes, apples, bell peppers, avocados, cucumbers, sweet potatoes, citrus fruits, peaches, pumpkins, eggplants, squash and hardshell nuts. Waxes are only used in small amounts, and are not considered harmful. Experts estimate that one pound of wax will cover 160,000 pieces of produce.
One potential cause for concern with waxes stems from the possible presence of pesticide and fumigant residues on the surface of the produce before the wax is applied. (In some cases, the pesticide or fumigant is mixed with the wax.) Ortho-phenylphenol is a type of anti-mold fumigant that's often used this way.
Chemicals cannot be washed off if embedded in a wax, but the health risk posed by the presence of such wax-bound pesticides or fumigant residues should be minimal if the chemicals are applied according to regulations. And, of course, it's only an issue for produce in which the skin is consumed.
Although you can try scrubbing these waxes off, it takes more than water to do the trick. A mild detergent, or products that claim to clean the wax off of produce (available at natural food stores) may be helpful. Without these, the only real way to "de-wax" the produce is to take off the peel.
It is important to understand that both conventional and organic growers can apply waxes as a protectant before shipping. All waxed produce should be labeled as such. Organic growers' waxes come from natural sources and do not contain any synthetic pesticides or fungicides. The presence of waxes is yet another reason why it's always best to consume a variety of fruits and vegetables, and change your selection with the seasons, rather than eating the same foods all the time.
Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 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.