Consider what youve eaten today. Perhaps you drank juice from a plastic bottle and coffee from a Keurig pod. For breakfast, you might have had fruit with yogurt. Your lunch salad may have been packed in a plastic container. Theres a good chance much of what you ingested was packaged, stored, heated, lined, or served in plastic. And unfortunately, theres mounting scientific evidence that these plastics are harming our health, from as early as our time in our mothers womb. Most of our food containers from bottles to the linings in aluminium cans to plastic wraps and salad bins are made using polycarbonate plastics, some of which have bioactive chemicals, like bisphenol A (BPA) and phthalates. These man-made chemicals can leach from the containers or wrappings into the food and drinks theyre holding especially when theyre heated. Research released earlier this year found that more than 90 percent of bottled water from the worlds leading brands was contaminated with microplastics, sparking a review of plastics in drinking water by the World Health Organization. The main cause for concern is that these chemicals can mess with our hormones. Specifically, they can mimic hormones like estrogen, interfere with important hormone pathways in the thyroid gland, and inhibit the effects of testosterone. Hormones are essential to the bodys ability to regulate itself; they function like little messengers, floating through the bloodstream and triggering different organs and systems to work together. Now imagine eating something that has a similar structure to your hormones and can act like hormones in your body. It can interfere with the delicate balance our bodies need to maintain. And thats what ingesting even low doses of chemicals from plastic, over years, can do. But because were exposed to these chemicals from many sources simultaneously, its tricky to measure their health impact. Even so, theres compelling evidence that their endocrine disrupting capabilities have a range of disturbing health effects, from an increased risk of obesity and diabetes to problems with reproductive development. Whatever organ or system under development in the foetus or child during an exposure could be altered in subtle yet significant ways, even at low doses, Tom Neltner, the chemicals policy director at the Environmental Defence Fund, told Vox. Thats why a major paediatricians group, the American Academy of Paediatrics, in July called on families to limit their use of plastic food containers and demanded urgently needed oversight and reforms to the way these substances are regulated in the US. But right now, thats not happening. So, as paediatricians have suggested, you might want to rethink the plastics your food is stored in. Heres what you need to know. In 2012, Harvard researchers published a study showing the effect of BPA on oocyte development (oocytes are the precursors to female eggs) in rhesus monkeys. By either directly feeding the monkeys BPA or giving them an implant that would release specific amounts of BPA, the scientists ensured BPA exposures in the monkeys were comparable to exposures in humans. They found disruption in two critical stages of egg development, which could lead to lower egg quality and decreased fertility.
A 2008 meta-analysis of existing literature looked specifically into the effect of phthalates and polyvinyl chloride (or PVC) on asthma and allergies. They brought together mouse studies, case studies, and epidemiological data. While the human data was inconclusive, the review concluded that certain phthalates can cause an inflammatory response in mice. A review published in 2009 looked at the existing literature on how plastic ingestion affects people and animals. It reported a wide range of effects that have been observed over the years: For example, adult male rats orally fed phthalates in oil had dysfunctional sperm development. Mice and guinea pigs fed phthalates also had testicular damage. One of the biggest problems with drawing conclusions from animal studies is that many of them involve very high doses several orders of magnitude higher than anything humans are exposed to, explained Dr. Frederick Vom Saal, an endocrinologist and professor emeritus at the University of Missouri and one of the authors of the 2009 review. And thats because much of the early research into plastic consumption was conducted by toxicologists, rather than endocrinologists. For toxins, the more youre exposed to, the greater the effect. [But] that is not true of hormones, he said. Hormones arent toxins; theyre regulatory molecules that operate at a trillionth of a gram level. In fact, hormones and plastics that mimic hormones are part of complex feedback systems in our bodies and dont have a linear effect thats directly related to dose. Vom Saal and his colleagues published a study in 2012 that found DEHP, a phthalate found in food packaging, had adverse reproductive effects in doses up to 25,000 times lower than had been previously imagined. They also noticed reproductive tract malformations in the male offspring of mice that were fed DEHP in oil. Altogether, the animal research suggests that plastics can be harmful, especially to animals reproductive systems, and can cause abnormal sperm, egg, and foetal development.
The human data isnt very reassuring
But again, not every health issue that arises in animals will arise in humans since humans and animals are different. And definitive human studies of health effects from plastics exposure are hard to come by. Thats because the studies are mostly epidemiological with epidemiological studies, researchers can only talk about associations between exposures and certain health outcomes. In other words, they cant find causal relationships. Another issue: Its not always clear what compounds a package is made of because manufacturing plastic polymers also yields a lot of by-products that arent necessarily tested for safety. Which means its hard to design studies to understand the effects of any single chemical. Even so, Carl-Gustaf Bornehag, a researcher and professor at the Icahn School of Medicine at Mount Sinai, summed up, Chemicals related to plastics BPA in polycarbonates and phthalates in soft polyvinyl chloride have been shown to be associated to human health effects in numerous studies, and effects have been shown in experimental cell and animal studies as well, supporting the finding in humans. Reviews of the literature on the human health effects of chemicals in plastics have demonstrated links between exposures to BPA, phthalates, and other plastics additives and reduced fertility, reduced male sexual function and sperm quality, blunted immune function, Type 2 diabetes, cardiovascular disease, and obesity. In foetuses, BPA exposure was correlated with an increased risk of miscarriage, low birth weight, and childhood obesity. There are also potential cognitive effects. Particularly strong are the associations between early BPA exposure and altered behaviour and disrupted neurodevelopment in children, as well as increased probability of childhood wheeze and asthma, the author of one of the reviews wrote. Indeed, children are at particular risk of health effects from these chemicals, AAP said: Hormones act on all parts of the body, and even small disruptions at key moments in development can have permanent and lifelong consequences. A 2015 systematic review of childrens neurodevelopment and phthalate exposure concluded that prenatal exposure to phthalates was associated with cognitive and behavioural outcomes in children, including lower IQ, and problems with attention, hyperactivity, and poorer social communication. Newer research has linked prenatal phthalate exposure to an increased risk of language development delays. While its true that many companies are now manufacturing phthalate- or BPA-free products, scientists are concerned about substitute chemicals, too. Again, many of them are functionally similar to the chemicals of concern, like BPA and BPS. The weight of the human evidence [on BPA] continues to mount, Sheela Sathyanarayana, an associate professor of paediatrics in the department of environmental and occupational health at the University of Washington and Seattle Childrens Research Institute, summed up. For phthalates, I do not see any controversies related to male reproductive toxicity, and the weight of the evidence is extremely strong. I now consistently say phthalates cause male reproductive abnormalities because the weight of the evidence supports it.
The regulation of chemicals in food containers is weak
Right now, its up to consumers to manage their exposures to the chemicals in plastics because of a surprising lack of regulatory oversight over the plastic packaging industry. In 1997, the FDA established the Packaging and Food Contact Substances program a regulatory system to determine what packaging products were safe. So, anyone who manufactures a food contact substance, which includes chemical additives, coatings, paper, or polymers, must first get the okay from the FDA before putting it on the market. The exception to this rule is substances considered Generally Recognised as Safe (GRAS) a category that was created for food items with a long history of use, like caffeine or sugar, and no evidence of harmful side effects. But the list of GRAS-accepted polymers in packaging is long some say too long. And its been criticised, most recently by the AAP. In August, members of the AAPs Council on Environmental Health noted just how easy it is to get into the GRAS category due to very little oversight and significant conflict of interest. Its one of the critical problems within the food regulatory system, they said, and it means these potentially harmful chemicals can be used in food packaging. Thats because the FDA doesnt actually test things that get put on this list. It leaves the decision up to the manufacturing companies themselves. Consumer Reports noted that these companies dont need to show any peer-reviewed evidence before placing their products on the GRAS list. The US Government Accountability Office has reported that regulations for GRAS products need to be tightened. An article published in PLOS Biology last year also criticised GRAS as part of the larger issue of sluggish federal regulatory policy that has failed in considering scientific knowledge about the impact of exposures particularly at low levels and during susceptible developmental stages. And last year, a group made of the Centre for Food Safety, Breast Cancer Prevention Partners, the Centre for Science in the Public Interest, the Environmental Defence Fund, and the Environmental Working Group sued the FDA over the secret GRAS system, calling it a regulatory scheme in which potentially unsafe chemical substances can be added to food based on conclusions by self-interested food and chemical manufacturers. In addition to the GRAS list, the AAP called out lack of proper assessment of controversial plastic packaging products like BPA and phthalates. Of the nearly 4,000 food additives listed on the FDAs Substances Added to Food website, data for effects on reproductive organs are available for less than 300, and only two have information about effects on development, the group said in a statement. One reason for this uncertainty is that our manufacturing abilities have whizzed past the slow nature of evidence-based research. Again, it is extremely difficult, if not impossible, to get the kind of evidence that would guarantee complete safety on these products, so the burden of proof is on regulators instead of manufacturers. Another more insidious reason regulators may have been dismissive of scientists concerns is lobbying by the chemical industry. According to the Centre for Responsive Politics, a non-profit organisation that tracks lobbying efforts, Dow Chemical, a plastics manufacturer, spent close to $14 million in 2016 on lobbying Congress and federal agencies. And the American Chemistry Council a large umbrella organisation that lobbies on behalf of plastic manufacturers, among other groups has spent between $5 million and $13 million on lobbying annually since 2009. Regulators have also been criticised for their research into BPAs health risks. The FDA-led CLARITY-BPA study, which began in 2012 and was released in the form of a draft report in February, gave BPA the green light, with a press announcement calling it safe for the currently authorized uses in food containers and packaging. The final study is slated to come out sometime in September, and will be considered with results from other government-sponsored BPA studies at universities. This initial reports early, positive conclusions were alarming to scientists who have been studying the chemical. In April, the Endocrine Society released a statement saying it had significant concerns with the conclusions of the [report] and criticized the methods and design of the CLARITY study.
What you can do to limit your exposure
In the absence of stronger regulations, there are things you can do to limit your exposure to chemicals in food:
- Eat fresh fruits and vegetables when possible, so that you avoid plasticized storage containers with chemicals that can leach into your foods.
- Dont microwave food or drinks (including infant formula and pumped human milk) in plastic since heating up food containers increases the release of chemicals into food. Use glassware instead.
- Opt for glass or stainless steel to store your food.
- Avoid plastics with recycling codes 3 (which means it contains phthalates), 6 (styrene), and 7 (bisphenols).
But even if you do all these things, its impossible to totally avoid these common chemicals. BPA can be found on sales receipts and in plastic utensils. As a recent story in GQ, about the declining sperm count in men, points out, phthalates are even more ubiquitous: They are in the coatings of pills and nutritional supplements; theyre used in gelling agents, lubricants, binders, emulsifying agents, and suspending agents. Not to mention medical devices, detergents and packaging, paint and modelling clay, pharmaceuticals and textiles and sex toys and nail polish and liquid soap and hair spray. And the plastics that we may not directly consume end up in landfills, where they break down into microplastics and can absorb harmful pollutants all of which can enter our oceans, water, and food supply. So, its no surprise that just about all Americans have measurable amounts of phthalates and BPA in their bodies. Still, any effort to reduce your exposure is probably worth it.
Vox, 4 December 2018 ; https://www.vox.com