Susan Freinkel is the author of the new book, Plastic: A Toxic Love Story.

She was kind enough to answer some health related questions about plastic based on her research for her book.

Is all plastic toxic?

There are lots of different kinds of plastic and some may pose more of a health hazard than others. The two experts are most worried about are:

Polycarbonate, a hard, clear plastic that has been used in baby bottles and sports water bottles. It is made with a chemical called Bisphenol A that is a weak estrogen mimic and which may suppress or alter the way the body uses its natural estrogen. Some studies have found an association between exposure to BPA and heart disease, breast cancer, prostate cancer, obesity and other health problems.

Polyvinyl chloride, also known as PVC or vinyl, is a source of concern for several reasons. PVC is made with a very toxic chemical, vinyl chloride, that can be a hazard to vinyl workers. If vinyl is incinerated, it can release dioxins which are potent carcinogens. And to make vinyl pliable and soft, manufacturers add oily chemicals called phthalates, some of which can interfere with natural hormones, including testosterone. Animal studies have shown that high doses of one such phthalate, DEHP, is toxic to the developing male reproductive system. There’s conflicting evidence about the effect of low doses – the kinds we may be exposed to through such everyday items as vinyl flooring, shower curtains or flip flops.  But some epidemiological studies have found an association between low-level exposures and various health issues including reduced sperm quality, disrupted thyroid function, changed immune response and liver troubles.

One reason for concern about these two chemicals is that they leach out of their plastic hosts fairly readily. Phthalates are not atomically bound to the vinyl, and so can migrate out pretty easily, especially in the presence of something fatty like cheese. And the molecular bonds of polycarbonate are loose enough that exposure to warm water and/detergents can allow some BPA to come free. Because both chemicals can leach out and are so widely used, most Americans harbor trace amounts of BPA and various phthalates in their systems.

Are there safe plastics?

There are many plastics that seem to be quite stable. Two that are considered reasonably safe – in part because they don’t need a lot of additives — are polyethylene (the stuff of plastic baggies and labeled either #2 or #4) and polypropylene (used in yogurt and margarine tubs and labeled #5).

What are hormone disrupters?

Hormone disrupters are chemicals that seem to interfere with the network of glands that orchestrate growth and development.  They may mimic or suppress hormones such as testosterone, estrogen, and thyroid hormone causing effects that effects can be complicated, subtle and may not show up for years or decades. Whether the amounts we are exposed to through plastics and other consumer products pose a serious threat to health is still a source of much debate within the scientific community. That said, if any group were to be affected by hormone disrupters, it would be fetuses, infants and children whose systems are still works in progress.

Is it true my child may have traces of synthetic chemicals in her system?

Unfortunately, most of us, even newborns, carry trace levels of various synthetic chemicals – including flame-retardants, solvents, anti-bacterial agents, plasticizers, pesticides and other substances — in our blood and urine. The mere presence of those chemicals does not necessarily mean they are causing health problems. Their presence simply indicates that you or your child has been exposed, Many of these chemicals pass quickly through the body. The big, still unanswered question is what, if any health risks, those small transient doses can cause over time.

Can I get rid of the chemicals in my or my child’s system?

It’s tough because synthetic chemicals are so pervasive, not only in plastics, but food packaging, cosmetics, soaps, furniture, medicines and a host of other things. But a recent study showed that people could dramatically reduce the levels of phthalates and BPA in their systems in just a few days by eating fresh, organic fruits and vegetables instead of canned and processed foods.

Is it safe to microwave foods in plastic?

It’s best not to microwave in plastic – or at least don’t microwave foods in plastic containers that don’t carry a label specifically indicating it’s safe for the microwave. The reason microwaving can be a problem is that heat increases the likelihood that any chemicals which can leach out, will do so.  If you are really concerned, use glass or ceramic containers to heat food in the microwave. If you do use plastic, steer clear of containers or plastic wrap that aren’t marked microwave-safe. And keep plastic wrap at least an inch away from the food since it can melt if it comes directly into contact with very hot food.

I’ve heard even BPA-free baby bottles are now considered dangerous?

Some of  the plastic bottles that replaced ones with BPA contain a related chemical which also may act as an estrogen mimic. These bottles are made of a type of plastic called polyethersulfone (PES). Others are made from a new kind of plastic called Triton, a relative of polyester, which so far, has been considered safe. If you are really concerned, you’d do best to look for glass bottles, or ones made of either polyethylene or polypropylene, two types of plastics that generally don’t require additives and therefore would be less likely to leach any chemicals.

What should I pack my kids lunch in since I can’t send glass containers?

One option is to use stainless steel tiffins, stacked food containers. You can also put sandwiches in wax paper or wax paper bags.  Tupperware is also probably pretty safe, since it is made from polyethylene, a relatively clean plastic.

Are the new “green” plastics any safer?

One would hope so, but there really is no guarantee because the main law regulating chemicals does not require manufacturers to demonstrate a chemical is safe before putting it on the marketplace. NatureWorks, which makes the most common new plastic, a corn-based plastic called Ingeo, claims a commitment to using non-toxic chemicals. And it requires any manufacturer using its plastic to abide by a “prohibited substances list”  which bars the use of various heavy metals, carcinogens, endocrine disrupters and other dangerous chemicals.

Are plastic toys dangerous? (We don’t eat them – how would the plastic affect me?)

Although children don’t eat the toys, they do mouth them, which is one way they might be exposed to any potential chemicals. But whether a given toy is dangerous depends on the type of plastic used to make the toy. Soft vinyl toys could leach phthalates although current federal law bars manufacturers from using the most worrisome phthalates in their toys. On the other hand, the only danger a toy like Legos poses if you happen to step on one of those sharp-edged bricks.

Is it true freezing water bottles releases carcinogenic dioxins?

This rumor circulating on the Internet and often attributed to Johns Hopkins School of Public Heath is a hoax. There are no dioxins in the plastic used in water bottles, and what’s more, freezing works against the release of chemicals. The main danger with reusing plastic water or soda bottles isn’t related to the chemicals in the plastic; it’s the bacteria from your mouth that can linger and get into the bottle and any fresh water you put in. Since it’s hard to really clean those bottles, you’d be better off using metal, glass or even BP-free plastic bottles that are designed for reuse.

Avril Swan is a family physician who blogs at Whole Family Medicine.

Submit a guest post and be heard on social media’s leading physician voice.