Dr Oz and phthalates

phthalateThe title of the segment on the Dr. Oz Show was “The Secret Ingredient Companies are Hiding in Your Food.” What could that be? Some opiate to keep you coming back for more? Tetrahydrocannabinol to increase appetite? No. The segment was all about chemicals called phthalates. And companies are not hiding their presence any more than they are “hiding” the presence of numerous substances that are not added to our food supply on purpose but can be detected through sophisticated analytical methods. These include pesticide residues, corrosion inhibitors, PCBs, detergents, chloroform, cadmium, radium, mercury, aflatoxins, bacteria and a host of others. Some of these are man-made, some occur naturally, but all are potentially toxic if present in a high enough dose. They end up in our food supply for the simple reason that if substances come into contact with each other, there will be a transfer of material from one to the other. If chloroform forms in water as a result of chlorination, which it does, some will be transferred to food that comes into contact with the water. Flourinated compounds used to produce grease-proof packaging can leave residues in food, aspergillus fungi can contaminate apple juice with their toxic metabolite patulin, wine may harbour residues of isinglass, a fish protein used to remove fine particles, and the potential carcinogen acrylamide forms when bread is baked.

None of these substances appears on food labels, not because there is some conspiracy to hide them, but because they are unavoidable. So it is with the phthalates. They do end up in our food supply because these chemicals have widespread applications. They lend flexibility conveyor belts, tubes used in milking machines and to plastic water pipes. They help the dispersal of pesticides, they’re found in caulking and in printing inks used on food packaging.

It’s no surprise to anyone familiar with chemical analysis that phthalates can be detected in our urine. Their presence, though, did come as a big surprise to the ten women Dr. Oz selected to have their urine analyzed for phthalates. None of the women had ever heard of phthalates before, which is quite surprising given the amount of publicity they have received. Their faces filled with panic when Oz revealed that they all tested positive for phthalates, chemicals that had been associated with endometriosis, weight gain, respiratory problems as well as brain and behaviour changes in children.

But here is the crux of the problem. Associations do not prove cause and effect. Just because women are more likely to suffer from endometriosis if they have higher levels of phthalates in their urine doesn’t mean that phthalates are the cause. Perhaps they have greater phthalate exposure because they eat more fatty foods like dairy and meat which are known to have higher amounts of phthalates. Perhaps they used more scented products most of which contain phthalates to inhibit the evaporation of the scent and they were somehow reacting to some of the numerous chemicals that make up scented products.

None of this is meant absolve phthalates from all blame because there are sufficient laboratory studies, animal experiments and human epidemiological data that suggest the need for further investigation. But there is no need for panic. There are numerous other substances that could be detected in our urine that could also be vilified in the same fashion as the phthalates. How many? At least 3,079 compounds can be detected, of which 2,282 come from diet, drugs, cosmetics or environmental exposure. Enough chemicals there for Dr. Oz to discuss and panic audiences for many years.


Joe Schwarcz

Mercury: How Much Exposure Is Toxic?

Dr. Joe on Mercury

Dr. Joe takes a look at Mercury amalgam cavity fillings and how much exposure is considered toxic.

What About Mercury In Fish?

mercuryNutritionists recommend eating fish regularly, twice a week, because it is an excellent source of proteins, vitamins, and omega-3 fats. These omega-3 fats are nicknamed the ‘healing fats’ because they are pivotal in preventing heart disease, certain forms of cancer, and other illnesses. But for the last decade, people have been worrying about eating too much fish because of possible contamination by methylmercury.

Because of its mobility, mercury is named after the messenger of the Gods in Roman mythology and the symbol Hg is derived from the Latin “hydrargyrum,” meaning liquid silver. Metallic mercury is not regarded as a serious contaminant in water because, like most metals, it is almost completely insoluble in water. In fact, the practice of storing metallic mercury under water was widely recommended to prevent release of toxic mercury vapor. Even soluble inorganic salts of mercury, in trace concentrations, were not considered hazardous to fish. How, then, does mercury accumulate in fish? When naturally occurring or industrial mercury is deposited in lakes and waterways, bacteria convert it to methylmercury, which then contaminates the food chain and builds up in tissues of fish and of wildlife that eat the fish. Methylation, which chemically bonds a carbon atom to the mercury atom, creates an organic compound that can move more readily through biological systems, and is more easily absorbed from the gastrointestinal tract. When methylmercury concentrates in the blood, it can affect the brain and the central nervous system by binding to the S-H groups of proteins, resulting in numbness, unsteadiness, tiredness, ringing in the ears, and problems with vision, hearing and speech. Moreover, eating fish to reduce the risk of having heart disease might not be such a good idea after all: recent studies have indicated that there could be a link between a high dietary intake of mercury from fish and coronary heart disease.

So, is eating fish good or bad? Let’s not forget what the father of medicine, Paracelsus, said during the Renaissance: ‘Only the dose makes the poison.’ The risks of mercury contamination in fish and shellfish depend on the amount of fish and shellfish eaten and the levels of mercury in the fish and shellfish. Since methylmercury concentration increases as you move up the food chain, small pan fish such as perch, rock bass and crappie are generally low in methylmercury. Older predatory fish such as walleyes, swordfish, sharks contain higher levels of methylmercury.

Pregnant women, women who might become pregnant, and children are advised to avoid some types of fish and only eat fish and shellfish that are lower in mercury. Methlymercury accumulates in the blood stream over time and is removed by the body naturally, but it may take over a year for the levels to drop significantly. Thus, it may be present in a woman even before she becomes pregnant, and affect the baby’s nervous system. This is why women who are trying to become pregnant should also avoid eating certain types of fish.

The question now, is how to benefit from eating fish and shellfish without being poisoned by mercury? First, avoid large fish because they contain higher levels of methylmercury. Second, eat up to 12 ounces (2 average meals) a week of a variety of fish and shellfish that are lower in mercury. Five of the most commonly eaten fish that are low in mercury are shrimp, canned light tuna, salmon, Pollock and catfish. Another commonly eaten fish, albacore (‘white’) tuna, has more mercury than canned light tuna. So when choosing your two meals of fish and shellfish, you may eat up to 6 ounces (one average meal) of albacore tuna per week. If you are not sure about the fish you’re eating, you can always check the FDA food safety website (www.cfsan.fda.gov/seafood1.html).

As long as you don’t overconsume, fish is an excellent part of the diet. Scientists may someday expand healthy choices by engineering omega-3 acids into chicken or beef. Omega-3-rich eggs are already on the market but they do not provide as much of these fats as fish do.

Blog authors are solely responsible for the content of the blogs listed in the directory. Neither the content of these blogs, nor the links to other web sites, are screened, approved, reviewed or endorsed by McGill University. The text and other material on these blogs are the opinion of the specific author and are not statements of advice, opinion, or information of McGill.