But that’s not actually true. Almost all pure plastics are inherently flammable. When exposed to heat and flame, the polymers in plastics split into smaller, more volatile pieces. As oxygen reacts with these new compounds, more heat is produced, further ensuring a combustion reaction. This chain reaction continues until all of the plastic is broken down.

On top of the actual flame, burning of plastics can also be dangerous as it can create toxic gasses from the chemical components. Thus, as you can imagine, flammability is a huge problem for plastics used anywhere where heat might occur – near currents in electronics, in the kitchen, even furniture. The only thing that keeps most plastics from going up in smoke are the flame retardants mixed into the plastics themselves.

Keeping the Flame at Bay

Flame retardants act to stop the chain reaction that heat and flame cause, either slowing or preventing the spread of the fire all together. Almost all plastics that we come in contact with have added flame retardants in them to prevent ignition. One of the most popular types of compounds used in plastics are brominated flame retardants. As the name suggests, they all contain bromine. These are applied to 2.5 million tons of plastic polymers annually. One particular group, polybrominated diphenyl ethers (PDBEs), are used so much that the world consumes 40,000 metric tons of it every year, with 34,000 or so of those being manufactured in North America.

The variety of products that use brominated flame retardants is astounding. They’re in:

• almost every piece of electronics you buy from TVs to computers
• carpets
• paints
• kitchen appliances
• upholstery
• car parts
• building materials

They’re so well used by the industry because they work great. Not only do they prevent ignition, they slow the spread of fire, giving anyone near it precious extra seconds to escape.

Of course, like the other compounds added to plastics, brominated flame retardants and PDBEs don’t all stay neatly wrapped up in the plastics they’re added to. They, like BPA and phthalates we covered earlier, tend to leech out into the environment, which is where the danger sets in.

What Are PBDEs? And why are low levels potentially dangerous?

With over 209 different compounds used, polybrominated diphenyl ethers (PDBEs) are the largest group of brominated flame retardants used in plastics. They’re split into two types: “lower brominated,” or containing less than 5 bromines, or “high brominated,” with more than five. The big concern is with the more popular lower brominated PBDEs, as they are known to bioaccumulate.

Most of the time, we worry about acute exposures. That’s when the body has a sudden, high dose of something bad for it, to the point that it can’t deal. For example, if you chug a 24 pack of Bud Light in less than an hour, you’ll probably get acute alcohol exposure and be rushed to the hospital. But, odds are that if you are treated fast enough and have your stomach pumped, you’ll be fine in a few days. Your body processes alcohol fairly quickly – though it might not seem like it when we’re horribly hungover. In that sense, most people don’t have to worry about PBDEs. While common, your daily exposure is pretty low, so unless you go chugging chemicals at a plastics plant you’re not likely to suffer from acute exposure to PBDEs.

Bioaccumulation is Different

Bioaccumulation refers to the amount of a substance, usually toxic, that occurs in an organism over a much greater period of time. It occurs when a substance is absorbed or stored at a faster rate than it is lost, causing it to ‘accumulate’ in the body. When bioaccumulation occurs, smaller environmental levels can have a much larger impact.

Imagine if every time you had a drink, your body simply couldn’t get rid of the alcohol in the beer, and instead, it lingered in your tissues. You could have one drink a week, but still within a few weeks you’d be drunk all the time. That’s what happens with PBDEs – they sit in your body, and don’t go anywhere. Unlike BPA where you have to have a threshold daily dose for effects to occur, PBDEs can be toxic at extraordinary low daily doses – it just takes longer for the effects to show.

PBDEs bioaccumulate in blood, breast milk, and fatty tissues. Because they’re so common, the average person is exposed to PDBEs from all kinds of places. You inhale them as they evaporate from building materials in your home and eat them when they leech from your tupperware. For that matter, it’s not just the plastics in your life you have to worry about.

Humans aren’t the only species that PDBEs bioaccumulate in, and as they become more prevalent in the environment, they become more prevalent in our foods. Significant concentrations have been found in popular foods like salmon, ground beef, butter and cheese. The higher up an animal is on the food chain, the more of a bioaccumulating compound it’s likely to have. And that’s not good news for us people, who reside squarely at the top.

There’s reason to fret about PBDEs – their close cousins have already been banned as health risks. You might have heard of them – polychlorinated biphenyls, or PCBs. They, too, were used as flame retardants, as well as other things, starting in the early 20th century.

It became clear, though, by the 1970s that PCBs were seriously dangerous organic pollutants, causing birth defects, impairing brain and memory functions, and increasing the risk of some forms of cancers. But that was not before General Electric released up to 1,300,000 lbs of PCBs into the Hudson River, prompting the New York State Department of Environmental Conservation to ban all fishing in the upper Hudson due to unacceptably high health risks to anyone who consumed their catch. And, unfortunately, GE was not alone. The effects of PCB use still linger today, especially in aquatic animals. And PBDEs are already accumulating – research has shown that PBDEs are at least as prevalent as PCBs in Lake Michigan salmon, for example.

Effects of PDBEs

In the United States, PBDE concentrations are rising, especially in children. Toddlers and preschoolers have 3 times higher blood concentrations of flame retardants than their mothers – an average of 62 parts per billion. And adults aren’t off the hook. A study in Spain in 2003 found that adult men there were chowing down 97 nanograms/day in their meals. No study has looked at the daily intake in the United States, although previous studies have shown that Americans rank among the highest in bodily concentrations of PBDEs. U.S. mothers, for example, had concentrations of PBDEs 75 times higher than the average levels in Europe. And no one, anywhere, has studied how much of what we ingest stays in our bodies, accumulating in our fatty tissues.

While “parts per billion” and “nanograms” might sound like a very small amount, it’s still dangerous, especially for kids. Even a single, low dose given to developing mice caused permanent behavioral and neurological changes. Other studies have found that over time, PBDEs alter thyroid function, disrupt brain development, drive cells towards cancerous activity and even cause hyperactivity.

Unfortunately, the study of PBDEs is still fairly new. It wasn’t until after the fiasco with PCBs that PBDEs were phased into use, and research has not had the time to fully study the long-term effects of these chemicals. What we have seen, however, isn’t looking good. Blood concentrations are quickly approaching the EPA’s magical “safety limit” for people, and research continues to show lower and lower doses having detrimental effects on animals.

Where We Go From Here

The good news is governments are taking notice of PBDE and the dangers involved. In the 1990s, the European Union began replacing brominated flame retardants, and levels in breast milk there have decreased in response. They one-upped themselves in 2006 by flat out banning the use of certain PBDEs in electronics. In the U.S., states like California, Hawaii, New York, Michigan and Maine have already passed PBDE banning legislation, and other states are following. But the federal government has yet to listen to the complaints against PBDEs or take any action against them.

The bad news is, if you live where it isn’t banned, there’s not much you can do to avoid it. Even if you do live where it’s no longer added, older furniture and plastics will still contain PBDEs. The best you can do is support organizations like Greenpeace which seek to see PBDEs banned entirely or petition your local politicians to make it an issue. There are alternatives to brominated flame retardants, and new technology continues to find ways around using harsh chemicals to prevent fires. We should to our best to remind industrial companies that being cheaper doesn’t make a chemical better – we need to find new ways to make what we need without poisoning our children and environment in the process.

Chemistry

Phthalates make plastic, well, plasticy. Many consumer goods are made up of very hard plastic compounds that do not allow finished products to move as required, like the PVC piping you find in many modern homes or the casing to your internet router.  And with a little phthalate magic added into the chemical mix, those PVC molecules that were once rigid in the pipes of your home are now free to form the flowing plastic carpet you often find beneath your feet.

In fact, these molecules are so unique and helpful, they have found their way into almost everything we use.  Personal care products, mechanical lubricants, paints, modeling clay, shower curtains, food containers and wrappers, even children’s toys all have some phthalates mixed in.  Health care items like the coatings of prescription pills and supplements are also guilty.

The magic of phthalates is that they allow the larger polymer plastic molecules to slide against one another more easily.  Phthalates move so well because they do not bond directly those large molecules, leaving them roam about in some cases.  Roaming phthalates leech away from their plastic motherships, leading to that new car smell, paint fumes and the heavy offgausing associated with new flooring.

Health Risk Debate

With the volume of phthalate in existence, our exposure to such materials is obviously high. Our main exposure is from what we eat but inhalation and absorption through the skin are also important factors.  Some scientists suggest that children are so regularly exposed to the plastic that they contain levels up to 20X what is known to be safe [1].  Part of the reason so little has been done about phthalates is that no one is perfectly sure what ‘safe’ really is.  So, the real debate with phthalates at this point has to do with quantity required to cause damage.

Suggested exposures depend heavily on body weight and stage of life.  On study gave a rough estimate 5-20 micrograms of phthalates per kilogram of body weight, with higher exposures in younger populations [2].  Other studies suggest that we really aren’t quite sure what the exposure levels are, and consequently all of this needs more study [3].  We do know that phthalates have been shown to cross the placenta and transfer from mother to fetus and such exposure has been linked to risk factors and the inital stages of prostate cancer and to changes in emotional stability as adults, all things we could do without.

Scientists classify phthalates as definite endocrine disruptors, a class of chemicals that throws off the body’s hormone signaling system.  Studies have shown high doses can cause birth defects in rats and even deformities in people.  Phthalates in particular are singled out from other plastics as a very possible epidemiological reason for the lower sperm counts seen across men in the Western world.

Such bold claims come from correlations found between phthalate exposure and young boys with shortened “anogenital distance”, decreased penis size and improperly descended testicles [4], all major public health issues facing 21st century policy makers.  Prenatal exposure was also shown to negatively effect reproductive development in young boys.

Youngest at the Greatest Risk

But of any one study, Pediatrics really turned the heat up on phthalates back in early 2008 when they reported that 81% of all infants had significant phthalate exposure from simple household items like shampoos, lotions and powders [5].  Most troublesome was the way in which researchers deduced how young infants might have the highest exposure: by simply being kids.  From the study (-ed emphasis mine):

Children have unique development and behavior that may predispose them to higher exposure susceptibility. When children are born, they immediately develop hand-to-mouth behaviors. They cannot move on their own and are therefore exposed predominantly to ambient air exposures, oral ingestion of breast milk/formula, and [skin] exposure to specific infant care products. As infants develop, they begin to move around, crawl, and have increased hand-to-mouth behaviors with the potential for increased exposure to phthalate sources in the environment.  But its not just children who have to worry, there is concern with adults too as phthalates have been linked to cancerous activity in adult cells.

Since this publication, the EU and the state of California have effectively banned many phthalates from the consumer market, with California more conservatively banning them from toys and children’s products.  These bans have been especially contentious because unsafe exposure levels remain unknown and, more importantly, the size of the industry in question.

The Political Dimension

Despite growing concerns and widespread exposure, phthalate exposure continues almost completely unabated in the United States.  One of the cardinal organizations responsible for this is the American Chemistry Council (ACC).  This group’s name spoofs the largest and arguably most respected scientific organization in the world – the American Chemical Society (ACS) – but it obeys a very different master: corporations.

The ACC represents all of the plastic companies and it obviously disagrees that phthalates cause problems.  They have been way out in front of this debate, publishing smears against phthalate detractors as recently as 2005 in prestigious medical journals.  They have even built a special website just for phthalates – http://www.americanchemistry.com/s_phthalate/ – and convened a “The Phthalate Esters Panel” to examine the facts through the warped lens of plastic manufacturers.

The ACC does show that a wide range of products depend upon phthalates, from vinyl siding to medical devices and raincoats.  Other important uses like duct tape and protection films for food products have all benefited society.  But the ACC stance ignores scientific progress being made by their own members.

Plastics without harmful phthalates have already been developed and deployed by major chemical companies like Dupont, with high customer satisfaction in some of the most demanding industrial environments.  Phthalate-free plastic welding is now also possible.  So it’s clear the innovations to move past phthalates are here today, giving manufacturers a bridge into the future of safer plastics from previous technologies like PVC.  What lacks are proper market forces or government regulation in the US to make the change occur.

Steps To Take

Here are some of the most basic steps you can take to protect yourself from this plastic:

• -Let new carpeting/vinyl flooring off-gas while you are not present
• -If painting, use proper ventilation to avoid excessive phthalate exposure
• -Buy new electronic items that are RoHS compliant (a European standard that bans some phthalates)
• -Buy consumer products in steel/glass when possible
• -Purchase newer toys for kids, as many companies must comply with California’s ban on phthalates

Small consumer purchases add up, so take account of what you are buying and try to avoid bendable plastics when you can.

Unfortunately, the very properties which make it so useful in so many industries are the same properties which make it one of the worst physical pollutant in the world. Despite recycling efforts, a large amount of plastic ends up in garbage cans (if we’re lucky) or littering the environment. Since the 1950s, one billion tons of plastic has been discarded by people. The ecological impact of all this plastic is devastating. Plastics make up at least 2/3 of marine litter, killing animals of all shapes and sizes. It takes over 450 years for a plastic bottle to degrade – that’s at least twice as long as it takes for an aluminum can to dissolve. And if that’s not bad enough, the forms of plastic that do degrade faster are even worse. Polystyrene – better know by the brand name “Styrofoam” – has been shown to degrade easily in seawater, but it leaves behind potentially damaging styrene molecules.

But this isn’t an article about the ecological impact of plastics – there’s enough on that for an entire book. The key question isn’t how does it affect the environment, it’s how does it affect us.

Plastic Chemistry 101

Plastics are very complex compounds chemically. They are made from combining various carbon-based compounds, called “monomers,” to create long chains, called “polymers.” The most common forms of plastic used are polyethylene, polypropylene and polystyrene. Their names explain what compounds are used to create them – polyethylene is made from strings of elthylene, polypropylene from strings of propylene, and polystyrene from strings of styrene. Another well-known plastic is polyvinyl chloride, better known as PVC. Another kind of plastic, polycarbonate, is made from bisphenol A (BPA), and is used extensively in our households in items like bottles, plastic glasses, tupperwares, even DVDs and CDs. There are actually hundreds of different types of plastic, all made from different carbon-based monomers. The different compounds lead to different properties, including different levels of hardness, flexibility, and heat resistance.

But there’s a lot more that goes into plastics than just the monomers. Other compounds can be added to further change the textural properties of the plastic. PVC, for example, often has phthalaes added to it to make it less brittle. These compounds are referred to as “plasticizers,” as they add to the fluidity of plastics. Some plasticizers eventually evaporate from the plastics they’re put into – for example, the “new car smell” we associate with a brand new Mercedes is caused mostly by trimelliate plasticizers evaporating from the car’s interior. Others leech out of plastics as they degrade or are exposed to extreme conditions, like the heat in microwave ovens. Bisphenol A is added to certain PVC to make it harder, and other compounds, like brominated flame retardants, make plastics less vulnerable to heat.

Luckily for us, most pure plastics that are free of such additives are fairly harmless. They are ecologically devastating because they take forever to degrade and ensnare marine and terrestrial animals, but as far as human use goes, they’re non-toxic. Unfortunately, most plastics we use aren’t pure. And even still, the compounds that make up pure plastics can be toxic, as the much more toxic, single monomers can be trapped in the plastic-making process only to be released later into our foods.

So what’s the harm, exactly?

What exactly do the chemicals in plastics do to the human body? A lot. And it depends on the compound. I’m going to dive into some of the big players and why you should know about them. First up is the one you’ve probably heard the most about: Bisphenol A, or BPA.

Bisphenol A

If you’ve paid attention to the news in the past year, you’ve probably heard a lot of talk about Bisphenol A. Like I mentioned before, it’s a monomer used to create polycarbonate plastics, labeled type 7, and also as a plasticizer in type 3 PVC plastics. It can leech out of either kind into food and water placed in contact with them.

BPA is what is called an “endocrine disruptor“. Our endocrine system is the system of signals and hormones which constantly communicate information between cells. The problem with BPA is that it looks similar enough to estrogen that our bodies can’t really tell the difference. Because estrogen is such an important hormone in our bodies (in men as well as women, by the way), the potential affects of BPA on our bodies are severe and range widely.

The first problem is that, so far, we’re not really sure how much BPA it takes to have a negative effect on our bodies, especially over a lifetime. It’s clear that a high, acute dose is bad, but where the bottom threshold is for humans is unclear. It wasn’t until 1997 that low-dose effects on laboratory animals were reported, though since then a variety of studies have used animal models to warn of the dangers of BPA.

In animals like mice and rate, doses as low as 0.025 µg/kg/day can causes permanent changes to the genital tract and predispose breast cells to cancerous activity. Between 1 and 30 µg/kg/day can lead to long-term reproductive changes like earlier puberty and longer periods, decline in testicular testosterone, and prostate cell changes indicative of cancer, as well as behavioral effects like decreased maternal instincts and even reversed sex roles. Basically, BPA exposure can affect almost every system in our bodies, particularly those impacted by reproductive hormones.

Think of anything that makes you manly or womanly – the shape of your body, your muscle mass, neurological systems – all are vulnerable to BPA’s toxic effects. Over 100 studies have been published which reveal different toxic impacts of BPA. The question isn’t “is it harmful,” it’s how harmful, and more specifically, at what dose.

After all, anything can be toxic when in excess. You can even die from drinking too much water. The big question now among scientists is what level of exposure to Bisphenol A is low enough that it won’t cause major, negative side effects in most people. They also are looking into how much BPA we get exposed to and from where. What they’ve found is that BPA exposure is particularly high in infants, when, of course, it has the most side effects. Developing people and animals are much more strongly affected by hormone levels and disruptors like BPA which mimic those hormones in our bodies. The younger the person, the more of an effect a lower dose of BPA has on them – which is bad news for pregnant moms and newborn infants. Levels that are safe for adults are likely to be unsafe for them. But, to date, no study has looked specifically at the effects of different doses of BPA on in-utero or newborn infant biology.

Exposure and Effects Still a Mystery

So what, you ask, is our daily exposure anyway? Well, we’re not entirely sure. Studies have found that infants can consume up to 13 µg/kg/day when fed formula from polycarbonate bottles. Remember – that’s a dose high enough to cause serious reproductive changes in animal models. Adults can get similar levels of BPA exposure from single servings of canned goods (they use a plastic lining to protect the metal) and some from plastic containers, particularly those that are warmed up in the microwave or run through the dishwasher. The EPA has said that 50 µg/kg/day is normal and safe, but recent studies in our closest relatives have shown that level causes adverse neurological effects, even in adults. And even worse, scientists have found that monkeys given 8 times that dose – 400 µg/kg/day – have blood concentrations lower than the average human being. It’s likely, therefore, that we’re getting a lot more BPA than we think, and its probably worse for us than we thought.

The first study of BPA’s effects on humans wasn’t published until September 2008. It looked at urine BPA levels in around 1,500 people to see if they correlated with disease. The researchers found that increased BPA levels were significantly associated with heart disease, diabetes, and high levels of certain liver enzymes. They concluded that “higher BPA exposure, reflected in higher urinary concentrations of BPA, may be associated with avoidable morbidity in the community-dwelling adult population.”  Many researchers claim we have known about this problem for far longer:

Despite the overwhelming evidence of the dangers of BPA, the FDA recently announced that it still deems the compound “safe.” This preliminary decision was attacked by scientists and consumer groups who said the FDA was being biased towards the industry and not taking into account the science and the safety of the American Public. Canadian officials have already banned BPA use in baby bottles, finding that levels were simply too close to unsafe for formula fed infants, a decision which lead to many leading companies like WalMart and Toys R Us to stop selling them in Canada and the U.S. In June 2009, the FDA decided to “reconsider” its assessment of BPA safety levels, though a new finding has yet to be announced.  Rumor has it that FDA’s next decision on BPA should come down the pipe in late November.

What To Do:

In the end, my recommendation is to steer clear of bisphenol A-containing plastics as much as possible, especially when it comes to your kids. Here is a list of easy ways you can avoid BPA:

• Be wary of all plastics labeled type 7
• Absolutely, positively, do not buy polycarbonate baby bottles
• Keep baby from putting hard plastics (like toys) in their mouths
• Replace older polycarbonate ‘Nalgene’-type water bottles with stainless steel bottles
• Replace canned foods, especially acid rich tomatoes, with those bought in glass
• Microwave your food in glass or ceramic containers instead of plastic ones like tupperware
• Use metal colanders in place of harder plastic ones for straining boiling water
• Hand-wash hard plastic kitchen cups and utensils in place of hot dishwasher cleaning

Sadly, BPA is only one of many toxic chemicals that can leech out of plastics. Next, I’ll tell you all about brominated flame retardants, called PBDEs, which unlike BPA, are found in almost every form of plastic.