Don’’t Eat Yellow Snow…or Black…or Brown…or Pink…

Question:My kids always want to eat snow. If I can help it, I don’t let them, but I can’t watch them all the time. It’s driving me crazy. What do you think?

Response:
If the snow is yellow, black, brown, pink or otherwise dirty, it should not be eaten, as the colors each point out the presence of a different kind of pollution – yellow pollution from animals, black and brown pollution from dirt, cars, and people, and pink from bacterial contamination. The snow can collect these pollutants once it falls to the ground by being stepped on, splashed on, or otherwise having pollution fall on it. More surprisingly, perhaps, snow can also become contaminated by pollution as it falls to the ground.

It turns out that snow is a fairly efficient pollution collector when it is in the air. Snow is formed by water vapor that moves in clouds in cold air. As the water vapor moves in the cold air, it can stick to a tiny piece of dust and then have other water molecules attach to it, forming a crystal. Once formed, the crystal can continue to grow and can stay in the air for hours before it falls to the ground. It is during this time that the snow crystal can collect or “scavenge” pollutants that are present in the air. As a result of this scavenging, snow can contain all kinds of airborne pollution, even if it is white and freshly fallen. They types of pollution that the snow can contain vary by location, but could include metals, acidic pollutants, and persistent organic pollutants (POPs). The amount of pollution in white, fresh snow is generally very low in rural areas and is higher in cities and other areas with a lot of traffic, since traffic is known to be a major air pollution source.

Even so, should you be worried? For white, freshly fallen snow, probably not, given that scientific studies show low amounts of pollution in fresh snow and given that kids generally don’t eat much snow. But for colored snow and for snow that has been sitting on the ground for a while, it is definitely best for your kids to look and not eat. A good way to show them why may be to melt some snow in a container and see what you find. Almost always, you will find dirt, sticks and other debris that were previously hidden.

Does an Organic Diet Matter?

Question: I only buy organic foods for my family, even though it is more expensive. I’ve always assumed that this reduces my family’s exposure to pesticides, but recently read in the news that this isn’t true. Does it?

Response: Yes, with qualifications.

Organic foods are essentially free of pesticides, while nearly every type of conventional fruit and vegetable has at least one type of pesticide applied to it sometime from when the seeds are put into the ground to when they are sold. Logically then, eating organic foods rather than conventional foods will reduce your family’s exposure to pesticides.

The qualifications relate to the amount and importance of that reduced exposure.

The amount of the reduction in pesticide exposures will, of course, depend on what your family eats. The best scientific studies of pesticide exposures from foods suggest that an organic diet will basically eliminate one microgram of pesticides that would otherwise be eaten on a conventional diet in a typical day. [Putting this microgram into perspective is difficult, but for what it’s worth, a person eating 1,800 calories a day will typically eat 70 grams (or 70,000,000 micrograms) of fat, while a wasp sting delivers about 2 micrograms of venom. Of course, these comparisons say nothing about their dangers, as the toxicity of the pesticides differs tremendously from that of the fat and venom.]

The impact of switching to an organic diet is illustrated by a Seattle, Washington study, in which 23 children ate non-organic foods on the first three days and last seven days of the study. On the days in between, the children ate organic fruits and vegetables in addition to conventional meat and dairy products. During the first and third stages of the study, every one of the children had measurable amounts of pesticide metabolites (which are the less toxic break-down products of pesticides) in their urine. During the second organic fruit and vegetable stage, the amount of metabolites for two common pesticides chlorpyrifos and malathion was about ten times lower than the conventional diet periods.



Whether these lower levels translate into less health risks is not known, since pesticide metabolite levels during both the organic and non-organic diet periods were lower than US EPA limits. Also, these lower levels do not consider pesticide exposures that occur through the air, soil, indoor dust and water. Although its contribution varies by pesticide and by person, for the average person, food is only a minor contributor to exposures many common pesticides, including chlorpyrifos (used mostly on cotton, corn, almonds, and orange and apple fruit trees) and permethrin (used mostly on cotton, wheat, corn, alfalfa, and poultry). For example, in one scientific study, food accounted for only a few percent of total exposure to chlorpyrifos, while breathing indoor air contributed more than 80%. As a result, it is quite possible that a diet of organic foods will have only a modest effect on total exposure to pesticides.

That said, a growing number of scientific studies have shown that exposures to even small amounts of pesticides are harmful, especially to young children – which I think provides a pretty persuasive reason for you to keep buying organic food. A steady organic food diet is a good and relatively easy way (costs notwithstanding) to lower your risks from pesticides.

Is Aluminum Cookware Bad for You?

Question:
I have a question about aluminum. I know the health risk aluminum can create for the body if one takes in too much as well as it's link to Alzheimers disease. I know that aluminum cookware, cans, and that antiperspirant can pose health risks. My question is about aluminum "cookware". I've heard cooking acidic foods in aluminum cookware can cause the aluminum to leach out of the pan so I've avoided them. However, I've found a high quality cast aluminum manual juicer by Ra Chand and I'm wondering if this all aluminum juicer will pose a significant risk to my health. Do you think the risk to my health will be high if I use it daily to squeeze oranges and other citrus fruits-especially because of their acidity? Could they cause enough leaching of aluminum for it to be a health risk? Or does the aluminum have to be exposed for a relative time period to the citrus for leaching to occur. What would you recommend?

Response:
Aluminum, a soft metal, is found nearly everywhere in the environment. Most exposures to aluminum occur through ingestion or eating and drinking, with daily intakes generally low, averaging between 30-50 mg. For the typical person, drinking water, medicines and other pharmaceuticals (such as antacids and antiperspirants) are the biggest contributors to aluminum exposures; however, aluminum cookware is also a potential source. As you note, aluminum exposures have raised some health concerns due to the effects of aluminum on the human nervous system and the much discussed (but inconclusive) linkages between aluminum exposures and Alzheimer's disease.

Aluminum exposures from cookware, of which more than half is made of aluminum, is not well studied, but is thought to be a relatively minor source of aluminum exposures. Exposures to aluminum through food can occur when aluminum leaches or otherwise dissolves from the cookware into the food. Leaching is most likely when the foods being cooked or stored are highly basic (like baking soda) or highly acidic (like tomato sauce, lemon juice, oranges, or vinegar). For example, tomato sauce has been shown to contain 3-6 mg aluminum (per 100 g serving) after cooking in aluminum pans, which translates into about one-tenth of the typical daily intake. This leaching of aluminum with acidic foods does not happen with aluminum cookware that is anodized, or electro-chemically processed to seal the aluminum in the cookware. Clemson University Extension’s Home and Garden Information Center tested different cookware types, and found anodized aluminum cookware to be safe. Regardless, it would probably be wise to store tomato sauce and other acidic foods in something other than an aluminum pot.

As for the juicer that you mention, I did a quick and non-exhaustive check of various websites, none of which said that the juicer is made of anodized aluminum. One site did say that it was made of acid-resistant aluminum and chrome, suggesting that the aluminum is somehow sealed and that leaching of aluminum will not occur during the juicing process. An easy way to check for this is to look at the juicer and see whether the aluminum becomes pitted or pock-marked after several uses. Since leaching takes time and juicing is a relatively quick process, this pitting would not occur immediately but would rather occur over time. As a result, you should probably continue to check your juicer for pitting over time.

Microwave Popcorn and the Kernel of Truth

Question:
For the past several years, I have been eating a bag of microwave popcorn almost every day. I just read that this can damage my lungs. Is this true? Should I be worried?

Answer:
Microwave popcorn has been around for more than 50 years, since the invention of microwave ovens. Microwave popcorn is relatively easy to make at home using popcorn, a brown bag, some staples (yes, staples!) and other ingredients, such as salt and butter. More commonly, people make popcorn in their microwave using ready-made microwave popcorn packages, many of which contain additional chemical ingredients. The chemicals that are used to give microwave popcorn its buttery flavor are the reason why microwave popcorn has been in the news recently.

In particular, scientific studies have linked diacetyl and other chemicals that give the popcorn its buttery flavor to lung damage in people that work in microwave popcorn factories. A study by the National Institute for Occupational Safety and Health (NIOSH), for example, showed that microwave popcorn workers were continually exposed to high levels of these buttery chemicals and that these high levels were related to a serious and permanent type of lung disease, often called "popcorn lung". These risks were shown in workers exposed every now and then to very high levels of butter-flavoring chemicals and also in workers continually exposed to lower (but still higher than normal) chemical levels. Similar findings have also been shown in other scientific studies of people and animals, providing important, supporting evidence that inhaling large amounts of butter-flavoring chemicals is dangerous to your health. These dangers to workers are well-accepted, as evidenced by the fact that just this week, the the US House of Representatives passed H.R. 2693, the Popcorn Workers Lung Disease Prevention Act.

Whether there are similar risks for the general microwave popcorn-eating public, has not been studied, but any potential risks should be limited to those eating popcorn with artificial butter flavoring. Even for these people, risks are thought to be low, since people preparing pre-packaged microwave popcorn at home are exposed to lower chemical levels and for much shorter time periods than the workers. Recently, however, health concerns were raised for people who eat a lot of pre-packaged microwave popcorn. In July 2007, a pulmonary doctor from Denver's National Jewish Medical and Research Center notified the U.S. Food and Drug Administration (FDA) of a patient who ate butter-flavored microwave popcorn several times a day for years and who now has a disease similar to "popcorn lung". As a result of this letter, FDA, the U.S. Centers for Disease Control (CDC), and the U.S. Environmental Protection Agency (EPA) are looking into the possible dangers of preparing pre-packaged microwave popcorn at home. Regardless of what they find, many makers of pre-packaged microwave popcorn have plans to stop adding diacetyl to their popcorn.

Until this time, there are several things that you can do to reduce any risks and/or your worry over pre-packaged microwave popcorn. Clearly, the most foolproof solution is to make microwave popcorn that does not contain artificial butter or to stick to homemade microwave or stove top popcorn. If you do prepare butter-flavored microwave popcorn, you can limit your exposures to the buttery chemicals by venting your microwave oven to the outside, opening nearby windows when you microwave the popcorn, letting the popcorn cool before you open the bag, and opening the popcorn bag outside.

Is Eating Seaweed Dangerous?

Question:
I was wondering if you could tell me how safe eating seaweed is these days, pollution wise. I hear lots about fish, but nothing about seaweed. Our family consumes 6-12 ounces a week. We buy organic, but it's wild caught. I eat seaweed in salads, sandwiches, and sushi. Mostly we just snack on dulse. -which I believe comes from the Atlantic. And we use Kombu, kelp, when cooking soups and beans. I believe the Kombu is local. We're in Santa Cruz, Ca. Thanks so much for your time!

Response:
Edible seaweed is a marine algae that can come in many forms, including the type that you mention kombu, as well as the commonly eaten wakame and nori seaweeds. Although long part of the Asian diet, edible seaweed has increasingly become a part of Western diets due to its well-documented nutritional and often discussed medicinal qualities.

In comparison, there is little information about the possible negative effects of eating seaweed. A couple of years ago, several governments, including the Canadian and British governments, issued warnings advising people not to eat one type of seaweed – hijiki – because of concern over high levels of inorganic arsenic, a toxic element that has been linked to cancer, that was found in seaweed samples. Since little was known about the specific risks of arsenic in hijiki, hijiki was not banned. The warnings, which were intended to give the consumers a choice, explicitly stated that eating hijiki occasionally was probably not dangerous. Importantly, the warnings did not apply to other more commonly eaten seaweeds, including arame, nori, kombu, and wakame, which were found to be free of arsenic.

Based on these and other concerns, several scientific studies have been performed to measure the amount of metals present in seaweed. Results from these studies show that metal contamination of seaweed depends on three major factors, including where the seaweed was harvested, the type of seaweed, and the specific metal. For example, in a small Canadian study (Van Netten et al., Science of the Total Environment, 2000), seaweed grown in waters near British Columbia, Canada generally had lower amounts of heavy metals, especially of mercury, than seaweeds grown in Japan and Norway, possibly due to lower amounts of these metals in British Columbia waters. All seaweed samples – even those grown in Japan and Norway – however, had metal levels that are generally thought of as safe to eat.

What this means for you and your family is that you can continue to enjoy your seaweed salads, soups, and sushi (although given the governmental warnings I would probably stay away from hijiki). Given seaweed’s many nutritional benefits and relatively low pollutant levels, seaweed is probably not only a safe food but also one that is good for your health.