Ruaridh Stewart/ZUMA Press/Corbis

Ruaridh Stewart/ZUMA Press/Corbis

As consumers search out a "BPA-free" label as a measure of a product's safety, science continues to indicate that such labels are not an indication that the product is risk-free. In the span of a week, three studies pointed out potential health hazards in various plastics. And without more precautionary testing and laws to safeguard against unknown toxins, experts say it's impossible for a consumer to buy a plastic product that is verifiably safe.

"As someone who works on this every single day, it's still hard for me to navigate the marketplace," said Lindsay Dahl, deputy director of Safer Chemicals, Healthy Families.

In one recent study, researchers were surprised to find that one of the main alternatives to BPA seems to be equally damaging -- despite its reputation is a "safe alternative." As an endocrine disruptor, BPA mimics the hormone estrogen, potentially causing a variety of health concerns. One of the unique qualities of BPA is that it only takes a small amount to produce effects.

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When researchers exposed rat cells to bisphenol S, a replacement chemical to BPA, they found that low levels of BPS acted in a similar manner.

"We didn't think would have those effects, but it's essentially the same as BPA," said Rene Vinas, one of the University of Texas researchers who conducted the BPS study published in Environmental Health Perspectives.

In another study, researchers from Taiwan found melamine in the urine of study participants who ate soup out of melamine bowls (melamine is a shatterproof plastic commonly used in tableware marketed toward children). While the amount was small -- up to 8 parts per billion -- melamine is a known carcinogen.

Here's where things get even more complicated: There's no way to know if the receipt you just grabbed or the BPA-free water bottle you sent your kid to school with is laced with BPS. And the FDA says that it takes 2,500 parts per billion of melamine in a person's blood to pose a risk -- so does that mean it's safe to pop your toddler's favorite robot plate in the microwave?

No one can say for sure.

"While in many cases the contents of food and personal care products list ingredients, rarely do they list ingredients for containers they are in," said Cheryl Watson, co-author of the BPS study.  "Even if you try to go by the recycling label on the container, it just lists the primary plastic, and not the other ones that may be mixed in. We know BPS is found in thermal paper – but who knows what else. "

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Health advocates say the system in the U.S. needs to be overhauled. Instead of assuming chemicals are safe until proven otherwise, the process needs to be reversed, Dahl said.

"I think it's time for consumers to really understand how broken our federal laws are on toxic chemicals," Dahl said. "Whether it's melamine bowls or BPA, we don't have strong federal laws to make sure chemicals are safe before they go into our products."

Minnesota became the first state to ban BPA in baby bottles and sippy cups in 2009, and while more states have introduced more comprehensive legislation "basically saying we can't play chemical whack-a-mole," Dahl said, her coalition is pushing for Congress to pass the Safe Chemicals Act, which would reverse that burden of proof.

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Laws have focused on children because the effects are bigger when the exposure occurs during development. But we may be just beginning to see the repercussions.

"Even though you and kids might not see effects, generations of exposure, grandchildren might see the effects eventually," Vinas said.

Meanwhile, some scientists are calling for a second wave of plastics that would focus on improved health and environmental safety and sustainability.

"We are in need of a second plastic revolution," said Rolf Halden, a researcher at Arizona State University's Biodesign Institute, in a press release announcing his new overview of plastics published in Reviews on Environmental Health. "The first one brought us the age of plastics, changing human society and enabling the birth and explosive growth of many industries. But the materials used to make plastics weren't chosen judiciously and we see the adverse consequences in widespread environmental pollution and unnecessary human exposure to harmful substances. Smart plastics of the future will be equally versatile but also non-toxic, biodegradable and made from renewable energy sources."

Vinas and Watson are hoping that more preliminary testing and screening could sift out toxic chemicals before they hit the market.

"If chemists and biologists work together, they [might be able to] screen out all these potentially bad chemicals that mimic hormones," Vinas said.

What can consumers do now? Glass and stainless steel containers make good substitutes for plastic, experts said. Feed your baby with a glass bottle, advised Arnold Schecter, a public health physician at the University of Texas School of Public Health in Dallas, and eat fresh produce instead of canned vegetables. Because BPS has been found in currency, Vinas avoids cash.

"Ideally, stay away from all of it until we find a chemical that doesn't leach," Vinas said. "But worrying about it is also probably not healthy."