BPA & phthalates migrate, leach and flake off of plastics primarily because they are not chemically bound to the plastic.
It’s important to understand that any specific plastic is a mixture of one or more polymers along with a variety of additives like BPA and phthalates that are added to provide desired characteristics such as color, strength, rigidity (or flexibility), and other qualities of the finished plastic.
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In some ways, polymers are like dry cement. Water can be added, and a hard substance results when it cures. Aggregates like sand and stone are mixed in to provide strength. Steel rebar is added for flexibility and tensile strength. Polymer fibers offer flexibility. Dyes are added for color.
An exothermic chemical reaction takes place when water is added to cement. But the sand, stones and re-bar are not part of the chemical reaction.
Just like plasticizers added to plastics, the additives to cement are not covalently bound to the concrete. Instead, those additives — whether to concrete or a plastic — are physically confined when the mixture cures, but can separate under many circumstances.
Rebar, stones, and even sand are massive compared with the tiny sizes of the plasticizer and additive molecules that give polymer chains the desired characteristics. Because of this, additives can migrate among the polymer chains and — when they reach the surface of the plastic — can easily leach or simply fall out of the plastic-like pebbles from old concrete.
What helps additives escape from the plastic?
Additives escape from plastic and enter the food chain or directly into people’s bodies through a combination of actions that include:
Mechanical- Scraping, friction, bending, stretching, twisting, or compressing plastic promotes microfractures that speed additive particles toward a surface. Friction between plastics or other components can create fine dust particles that accelerate the release of additives.
Mechanical stressors are particularly applicable to conveyor belts, squeezable condiment containers, plastic utensils in contact with plastic bowls or paper plates (most of which have a plastic coating), plastic gloves, and plastic beverage containers.
Children frequently treat their plastic toys and other objects with less than tender loving care.
Light – Degrades plastic and accelerates the release of plastic additives.
Chemical action – Acidic foods and beverages can react with a variety of additives because those are not chemically bound (covalently) to the polymers. Some polymers may also be subject to reacting with acids or other food and beverage compounds.
Lipophilia – Promotes absorption of chemicals in oil-based foods. Studies show that people can absorb BPA from touching thermal paper cash receipts. What’s more, those who use hand moisturizers absorb far more BPA because of the increased lipids from the hand cream.
Heat – Adds energy to the migration process, speeds up chemical reactions that can loosen bonds.
Lipophilia: for the love of fat
In scientific terms, fats and oils are known as lipids. Lipophilia means a “love of lipids.” Fats tend to be solid (or relatively so) at room temperature and oils, liquid.
Significantly, BPA, phthalates, and many other harmful environmental chemicals are “lipophilic” — they are easily dissolved in fats and oils.
This should not be surprising because most environmental chemicals — including endocrine disruptors and pesticides — are derived from petroleum. The same goes for artificial fragrances, flavor enhancers and food coloring as well as plastics in general, and the printing inks used on them.
What this means is that contact between plastic and any form of food-based oil or fat results in increased migration of BPA, phthalates, and other chemicals from the plastic and into the edible portions of the food.
While there is no valid science yet, there is a logical possibility that the health stigma of fat in the diet and its role in obesity may be due more to the presence of harmful environmental chemicals in the fat, rather than its metabolism and actual calorie count.
Scores of well-designed, peer-reviewed, published studies have shown that BPA and phthalates act as “obesogens” — substances that disrupt the metabolic process and result in the preferential storage of fat rather than its use as energy.
Why does lipophilia matter?
The opposite of lipophilic is hydrophobic — the fear of water. This means that harmful environmental chemicals are somewhat less likely to leach into foods and beverages that are water-based.
Despite that, BPA (hydrophobic) still leaches into the water of plastic bottles.
The migration of BPA, phthalates, and other lipophilic chemicals is preferentially accelerated when placed in contact with lipids — fats and oils — whether from foods like bacon or cooking oils.
This means that even very heart-healthy foods like olive oil packed in plastic bottles could contain higher concentrations of BPA and phthalates than those in glass bottles.
Impacts cooking and processing
Lipophilia impacts both cooking and processing.
In cooking, the BPA and phthalates in plastic mixing bowls, utensils, and other items can migrate into the foods themselves.
Heat will further encourage migration of chemicals from plastics. This includes microwaving food in plastic, allowing warm or hot foods to come into contact with plastic bowls, dishes, or cooking with plastic utensils.