By Jessica A. Knoblauch
Environmental Health News
July 2, 2009
avrenim_acceber/flickr |
Plastic water bottles. |
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.
The
amount of plastic manufactured in the first ten years of this century
will approach the total produced in the entire last century 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.
Unfortunately,
collecting data on plasticizers’ impacts on wildlife suffers the same
pitfalls as studying human health. Still, there is already evidence
that chemicals associated plastics might harm wildlife.
For
example, laboratory studies have shown that phthalates and BPA affect
reproduction in all studied animal groups and impair development in
crustaceans and amphibians.
“While there is clear evidence that
these chemicals have adverse effects at environmentally relevant
concentrations in laboratory studies, there is a need for further
research to establish population-level effects in the natural
environment,” according to the report.
Charles Tyler, a professor
at the University of Exeter School of Biosciences in the United Kingdom
and a senior author of the report, said that scientists have shown that
“some of these chemical compounds are getting into the environment and
are in some environments at concentrations where they can produce
biological effects in a range of wildlife species.”
Traveling
from coast to coast, plastic can endure for thousands of years due to
the reduced UV exposure and lower temperatures of aquatic habitats.
Barnes
demonstrates plastic’s mobility with his account of a plastic sighting
during an expedition to the Amundsen Sea where he took biological
samples, the first there ever. The Amundsen, located in the Pacific
Sector of Antarctica, is the only sea in Antarctica with no research
station on its coast and the nearest urban center thousands of miles
away.
“Even for us, getting in was a challenge because there’s so
much ice and it’s so difficult to get there,” said Barnes. “But even in
that remotest of environments, there was plastic floating on the sea
surface.
Plastic also serves as a floating transportation device
that allows alien species to hitchhike to unfamiliar parts of the
world, threatening biodiversity. Global warming further aids the
process by making previously inhospitable areas like the Arctic livable
for invasive species, which can be detrimental to local species.
For
example, plastic items are commonly colonized by barnacles, tubeworms
and algae. Along the shore of Adelaide Island, west of the Antarctic
Peninsula, ten species of invertebrates were found attached to plastic
strapping that was littering the ice.
“Raising the temperature
just one degree can make the difference between getting to someplace
and actually surviving once you get there,” said Barnes.
Plastic
is so resilient that even burying it deep within the earth doesn’t keep
it from impacting the environment. Currently it accounts for
approximately 10 percent of generated waste, most of which is
landfilled. But, as the report notes, placing plastics in a landfill
may simply be storing a problem for the future, as plastic’s chemicals
often sink into nearby land, contaminating groundwater.
In
addition, production of plastics is a major user of fossil fuels. Eight
percent of world oil production goes to manufacturing plastics.
As
plastics grow in volume at a rate of about nine percent each year, the
authors emphasize that tackling its problems means addressing its
sustainability.
One solution is to treat plastic as a reusable
material rather than as a disposable commodity that’s quickly
discarded. That means making plastic more easily recyclable from the
get-go by using fewer materials in the manufacturing process and
increasing recycling facility availability.
“The recycling
message is simple; both industry and society need to regard end-of-life
items, including plastics, as raw materials rather than waste,” stated
the report.
Increasing the availability of biodegradable plastic,
which can be made from renewable materials from plants such as corn and
soy, is another option.
“Biodegradable plastics have the
potential to solve a number of waste-management issues, especially for
disposable packaging that cannot be easily separated from organic waste
in catering or from agricultural applications,” according to the report.
However,
currently production capacity for biodegradable plastics worldwide is
around only 350,000 tons, representing less than 0.2 percent of
petrochemical-based plastic. In addition, “most of these materials are
unlikely to degrade quickly in natural habitats, and there is concern
that degradable, oil-based polymers could merely disintegrate into
small pieces that are not in themselves any more degradable than
conventional plastic,” stated the report.
To help mitigate the
potentially harmful chemicals in plastics, the authors recommend that
more studies be conducted on the biological mechanisms that may be
affected by plastic additives and in particular, low-dose chronic
exposures.
In the meantime, the report recommends reducing the
use of these chemicals and developing safer alternatives, a strategy
known as green chemistry.
“Had this approach been in place 50
years ago it would probably have prevented the development of chemicals
that are recognized as likely endocrine disruptors,” the report said.
The
report also suggests that plastic waste can be reduced by using labels
that allow consumers to choose packaging based on a lifecycle analysis
that includes all components of the manufacturing process. For example,
if the product were made of mostly recycled materials, used minimal
packaging and could be easily recycled, it would get a green dot. If
the product were made of excessive packaging that used a lot of virgin
materials, it would get a red dot.
“Personally, I feel that’s the
way to do it, rather than a knee jerk reaction where legislation says
we can’t use certain types of plastic,” said Thompson. “Having that
information will help drive the system because I think consumers are
keen to make the right choice when provided with all the information.”
Paul L. Nettles/flickr |
Plastic pellets often spill during transportation to manufacturing plants. These are from a spill near Pineville LA. |
Neal of PlasticsEurope said consumers, not the industry, are
responsible for making sure plastics don’t wind up littering the
environment.
“In my view the responsibility is fairly and squarely on
the consumer,” he said. “People tend to pick on plastics because
perhaps it’s the most visible form of litter and because it’s
lightweight so it can move around a bit, but actually it’s only a small
part of the litter problem.”
The authors said that if plastics are made and used responsibly, they can help solve some environmental problems.
For
example, one study found that packaging beverages in PET (a type of
plastic) versus glass or metal reduces energy use by 52 percent and
greenhouse gas emissions by 55 percent. And, solar water heaters
containing plastics can provide up to two-thirds of a household’s
annual hot water demand, reducing energy consumption.
Plastics, if used wisely, “have the potential to reduce mankind’s footprint on the Earth,” Thompson said.