From cell phones and computers to bicycle helmets and hospital IV bags, plastic has molded society in many ways that make life both easier and safer. But the synthetic material also has left harmful imprints on the environment and perhaps human health, according to a new compilation of articles authored by scientists from around the world.
More than 60 scientists contributed to the new report, which aims to present the first comprehensive review of the impact of plastics on the environment and human health, and offer possible solutions.
“One of the most ubiquitous and long-lasting recent changes to the surface of our planet is the accumulation and fragmentation of plastics,” wrote David Barnes, a lead author and researcher for the British Antarctic Survey. The report was published this month in a theme issue of Philosophical Transactions of The Royal Society B, a scientific journal.
As the scrutiny of the environmental toll of plastic increases, so has its usage, the scientists reported.
Since its mass production began in the 1940s, plastic’s wide range of unique properties has propelled it to an essential status in society. Next year, more than 300 million tons will be produced worldwide. The amount of plastic manufactured in the first ten years of this century will approach the total produced in the entire last century, according to the report.
“Plastics are very long-lived products that could potentially have service over decades, and yet our main use of these lightweight, inexpensive materials are as single-use items that will go to the garbage dump within a year, where they’ll persist for centuries,” Richard Thompson, lead editor of the report, said in an interview.
Evidence is mounting that the chemical building blocks that make plastics so versatile are the same components that might harm people and the environment. And its production and disposal contribute to an array of environmental problems, too. For example:
• Chemicals added to plastics are absorbed by human bodies. Some of these compounds have been found to alter hormones or have other potential human health effects.
• Plastic debris, laced with chemicals and often ingested by marine animals, can injure or poison wildlife.
• Floating plastic waste, which can survive for thousands of years in water, serves as mini transportation devices for invasive species, disrupting habitats.
• Plastic buried deep in landfills can leach harmful chemicals that spread into groundwater.
• Around 4 percent of world oil production is used as a feedstock to make plastics, and a similar amount is consumed as energy in the process.
People are exposed to chemicals from plastic multiple times per day through the air, dust, water, food and use of consumer products.
For example, phthalates are used as plasticizers in the manufacture of vinyl flooring and wall coverings, food packaging and medical devices. Eight out of every ten babies, and nearly all adults, have measurable levels of phthalates in their bodies.
In addition, bisphenol A (BPA), found in polycarbonate bottles and the linings of food and beverage cans, can leach into food and drinks. The U.S. Centers for Disease Control and Prevention reported that 93 percent of people had detectable levels of BPA in their urine.
The report noted that the high exposure of premature infants in neonatal intensive care units to both BPA and phthalates is of “great concern.”
Polybrominated diphenyl ethers or PBDEs, which are flame-retardants added to polyurethane foam furniture cushions, mattresses, carpet pads and automobile seats, also are widespread.
The plastics industry maintains that its products are safe after decades of testing.
“Every additive that we use is very carefully evaluated, not just by the industry, but also independently by government agencies to look at all the materials we use in plastics,” said Mike Neal, a consumer and environmental affairs specialist at PlasticsEurope, an industry trade association, and a co-author of the report.
But some of these chemicals have been shown to affect reproduction and development in animal studies, according to the report. Some studies also have linked these chemicals with adverse effects in people, including reproductive abnormalities.
“We have animal literature, which shows direct links between exposure and adverse health outcomes, the limited human studies, and the fact that 90 to 100 percent of the population has measurable levels of these compounds in their bodies,” said John Meeker, an assistant professor of environmental health sciences at the University of Michigan School of Public Health and a lead author. “You take the whole picture and it does raise concerns, but more research is needed.”
Shanna Swan, director of the University of Rochester’s Center for Reproductive Epidemiology, conducted studies that found an association between pregnant women’s exposure to phthalates and altered genital development in their baby boys.
Also, people with the highest exposure to BPA have an increased rate of heart disease and diabetes, according to one recent study. Animal tests studies of PBDEs have revealed the potential for damaging the developing brain and the reproductive system.
Yet the effects on human health remain largely unknown. To help shed more light on the issue, the report recommends more sophisticated human studies.
“It’s tough to have a smoking gun with a single animal study or observational human study,” Meeker said. “We need to have different types of studies indicating a consistent pattern to more definitively determine health effects resulting from these chemicals.”
But testing humans for endocrine disruptors can be tricky because phthalates and BPA pass through the body so quickly. In addition, tests for each chemical cost about $100 a pop.
Deciding which chemicals to test and at what dose is also an issue. To date, most studies have addressed single chemicals, and there are limited data on the interactions between chemicals. Compounding the problem is the discovery that endocrine disrupting chemicals may have effects at doses lower than those used in the Environmental Protection Agency’s standard toxicity tests.
Swan said the old model of testing should be thrown out and that the new goal should be tests that mimic real human exposure.
“It’s a very complicated picture and the laboratory model of just taking one isolated chemical and giving it to a genetically pure strain of rats in clean cages, clean air and clean water and seeing what it does just doesn’t come close to mimicking the human situation,” she said.
Many researchers recommend studies that test pregnant women as well as their children. The National Children’s Study will do just that by examining environmental influences on more than 100,000 children across the United States, following them from before birth until age 21.
“There are so many questions now with these chemicals in relation to cardiovascular disease, age and puberty, obesity, developmental disorders,” said Swan. “We don’t know what’s causing it, only hints, so the beauty of the National Children’s Study is that we can look at all of these endpoints and it should reveal a lot of answers.”
Plastic’s problems extend beyond the human body, according to the report. More than one-third of all plastic is disposable packaging like bottles and bags, many of which end up littering the environment.
Although the image of a bird tangled in a plastic necklace is by now burned into the public’s eye, ingestion of plastic fragments is much more common. Once inside, plastic can pack a one-two punch by both clogging an animal’s stomach and poisoning it with chemicals that have concentrated in the plastic. Some chemicals are then transferred to the food web when animals eat them.
More than 180 species of animals have been documented to ingest plastic debris, including birds, fish, turtles and marine mammals, according to the report.
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