Plastics at Sea

I will never experience a Thanksgiving quite like the one I did five years ago.  I was just returning from a semester of sailing from Massachusetts down into the Caribbean conducting marine science research aboard the Corwith Cramer.  The friends I made and experiences we shared were unforgettable.  I had this adventure with Sea Education Association (SEA), which is an amazing educational sailing program that focuses on a variety of marine sciences.

My best mate and me!

Some rough seas in the Northern Atlatnic

The Corwith Cramer

If you follow news about plastics in the ocean, you may be aware that in addition to the Great Pacific Garbage Patch, there are four other "garbage patches" in the oceans.  SEA has conducted over 25 years of research in the Atlantic Ocean to identify the garbage in the North Atlantic Subtropical Gyre.  More than 64,000 individual plastic pieces were collected at 6100 locations that were sampled yearly over the course of the study, and the results were published in the journal Science last year.  On my sail in 2006, I can remember our net tows every 12 hours, in which we lowered the giant net into the water alongside the ship for an hour, and hauled up the net to examine its contents.  My research was on the migrating patterns of conger eels, so in addition to collecting eel larvae, I also had to sort through lots of tiny plastic bits.  The lighter plastics, such as low density polyethylene (recycling number 4), float, whereas the heavier plastics, such as high density polyethylene (recycling number 2) sink.  This means that we don't see the heavier plastics that sink to the bottom of the ocean floor, while milk jugs, pen caps, wrappers, etc. float near the surface of the water.  So, where did these plastics come from, and what impact do they have on oceans?

Not surprisingly, a lot of this waste comes from land sources.  All of the litter on the ground that is washed downstream or directly into our harbors and rivers, is eventually carried out to sea.  The surface ocean currents determine where the debris accumulate, which happens to be in a high concentration a few hundred miles off the coast of Georgia, in this case.  Some may place the blame on barges and cruise ships, but international ocean dumping laws were created in 1988 to prevent dumping waste into the ocean.  Although I am sure that some of the garbage comes from unregulated ocean dumping, I am also sure that our land-based impact is the major contributor of plastics in the ocean.

These plastics are dangerous for ocean wildlife because they are subject to photodegradation.  Ultraviolet light degrades the plastics into extremely small particles.  These particles are mistaken for phytoplankton by marine animals (including birds) and ingested as food.  There are millions of sad stories about sick or deceased animals from eating or becoming entangled in plastic.  Oceanographer hero, Sylvia Earle, says that the fate our lives and the oceans are one; the ocean provides us with 85% of the atmosphere's oxygen.  If we do not take care of the oceans and the diverse life within them, we are ultimately harming mankind's longevity.  SEA, along with many other researchers, have shown that now is the time to re-think plastic production and disposal.  The ocean is not our garbage can.

Cool Bag Alternatives

I think it's about time I wrote something a little bit more light-hearted.  My classes are nearing the end of the semester, and while my stress levels are ramping up, I need to step back and think about the fun and positive impacts we can make.  My friend sent me the link to this great DIY blog post about using alternative produce bags!

I think is great because so many of us bring our own bags to the grocery so we don't contribute to plastic waste, but what about our produce?  I admit that I forgo the plastic produce bags and just drop everything in my canvas bags.  But there are times when you want to keep your green beans in line, so they don't scatter throughout the hummus, bread, or other items!  These T-shirt bags are the perfect solution.  You simply follow Delia's instructions for cutting your old T (and if you're like me, there is no shortage of old band/college/#passépunk shirts stuffed in a drawer somewhere...).   This will be a fun project for me while I take short breaks from studying this weekend, and I look forward to keeping my lettuce leaves, sprouts, and any other bulk produce items in their place!  I will probably also make one or two without the slits cut in the side for bulk granola and nuts.

If any of you have other cool ways to curb plastic bag use, I'd love to hear about them!!

Backpacks and Carpets and Fleece, Oh My!

I have been thinking about the manufacturing and recycling processes of plastics for a couple of years.  I thought I knew a fair amount on the topic until a friend recently told me that he's working with a company that turns PET plastics (resin identification code 1) into yarn to make fabrics for goods such as backpacks.  You may have already heard of this concept for making fleece fiber or tote bags.  The kicker here is that my friend is integrating solar panels into this fabric - that's a different story though.  We were wondering if any components from the PET would still be able to volatilize or evaporate from the final good, potentially posing any health concerns for consumers.

I have to admit that I have thought of this before, although I didn't have the skills to investigate the question.  I previously worked at a LEED certified school where the carpets were made from 100% post consumer content PET recycled material.  I always wondered if the children playing on the carpets, putting their hands in their mouths, breathing so close to the ground, etc. were experiencing any ingestion or inhalation of unseen bad chemical actors.  Because many carpets made from recycled content use PET materials, I am going to attempt to answer both of these questions.

In order to start thinking about this, we need to describe PET, or polyethylene terephthalate.  By the way, don't be confused by the "phthalate" in its name; the phthalates that are cause for concern have different chemical structures.  If you can remember high school biology, I am sure you've heard that structure and function are closely related.  So, PET is made from joining terephthalic acid with thylene glycol, using antimony as a catalyst.  High heat and pressure are applied over some period of time to make the polymers 150 times longer.  Copolymer blends can now be used and still retain PET labeling, according to the FDA.  PET is assumed to be toxicant-free and safe for food and beverage containers; you will see the number 1 on the bottom of soda, water, and juice bottles, as well as condiment containers and trays you can put in the oven (like frozen dinners).   However, many studies have shown various water bottle brands leach phthalates, as seen from bioassays that reveal varying degrees of estrogenic activity observed in mudsnails and yeast cultures.  Additional studies show the measurements of phthalates leaching from water bottles vary according to temperature and length of time.  But wait a minute, PET isn't made using phthalates!  How did they get into water bottles?  As of 2008, some new PET has been made from recycled PET, and although the recycling process begins with washing the containers, not all substances that have adsorbed onto the plastic are removed.  Also, as previously mentioned, copolymers can be used in PET production, so there is variation in components of the manufacturing process.  Researchers found different levels of phthalates, such as DMP, in soda bottles as compared to water bottles.  "DMP [was found] in concentrations as high as 3,000 μg/L in PET-bottled soda, whereas they were unable to detect DMP at all in PET-bottled mineral water.  One possible explanation is that the soda, perhaps because of its lower pH, promoted leaching of DMP from the PET bottle wall.  However, it is also possible that the PET used in production of the bottles intended for soda had a different provenance than the PET used in production of the bottles intended for mineral water."  So bringing this back to backpacks and carpets . . . well, maybe it's a good thing we don't drink out of them?  And what about the children playing on the carpets and the people with backpacks on their skin?  I think it's becoming clear how complicated this business of determining the safety of chemicals really is!

Phthalates are characterized by their lack of a covalent bond (remember those strong, electron-sharing bonds from chemistry) with the plastic compound they are mixed in.  There are 26 common types of phthalates that differ by their chemical structure and volatility.  A paper published from the Silent Spring Institute tells us that some phthalates, such as DEP, DMP, DBP are more likely to be found in indoor air, and higher temperatures lead to higher air concentrations of these compounds.  DEHP and BBP, which are heavier and used in PVC materials, are more commonly found in dust.  It has also been established that some phthalates are absorbed through the skin, as examined by studies conducted in the context of personal care products, many of which contain phthalates.  I haven't yet found a satisfactory examination of dermally absorbed phthalates and the necessary amount that may affect human health, but I will continue looking and let you know what I find.

So in order to answer the question about backpacks and carpets made from PET, we would need to get a better look at the specific phthalates that may be present in these products.  Because PET generally doesn't (or isn't supposed to) contain phthalates, my initial guess would be that most products made from PET would be safe.  Also, we are not eating out of backpacks or carpets, and generally not rubbing them into our skin.   However, if sufficient amounts of volatile or heavy phthalates were contaminants in the PET, there would be reason to look at the volatility and dust content of the recycled goods.  I would also want to look at recycled content fleece fibers, such as those made by Patagonia.  Because the market price for PET flakes (used for recycling) has more than doubled since 2007, we will continue to see an increase in PET products, and I would be surprised the safety of these recycled products doesn't continue to be examined.  This is just the tip of the iceberg however.  There are recycling numbers 2-7 as well!  What is in those, and what is being made from those recycled products?  I am sure you are anxious to know, but I will have to conduct another round of research and tell you about it another day!

Asthma and Autism, What's the Connection with Plastic?

So instead of jumping into the manufacturing of plastics, I will pick up on a piece that wasn't adequately addressed in my last post.  I always think about the dangers of sensationalizing associations; there is a lot of stress and worry over unsubstantiated claims out there!  My hope is for this blog to generate a fair and critical discussion about thoughts and concerns over plastics.  However, I fear I was too dismissive of evidence of phthalate (a component of plastics and fragrances) exposure and asthma or autism.  After writing that I had never heard of such association, it was a topic of discussion in one of my classes the very next day!  I thought this would be a very relevant post because so many of us are affected by asthma and autism, either directly, or through people that we know.  So without getting too caught up in the biology of this, I'll try to explain how these associations exist.

To start talking about asthma, we first need to briefly put it in the context of allergies.  Allergies are basically an over-reaction to harmless substances by our immune system.  The immune system is our body's defense for any kind of foreign substances, such as viruses or bacterias, and the way we are able to fight off harmful substances (like the influenza virus) is through the work of T and B cells in our immune system.  These cells produce antibodies, which are formed to recognize antigens, or outside substances.  An over-production of antibodies can lead to allergic responses, such as hives, swelling, or asthma.  Asthma is an allergy that occurs specifically in the lung.  So where do plastics play a role here?  Well, some chemicals can act in a way that enhances the immune response.  "Enhances" is emphasized because it means that such a chemical alone can't stimulate an immune response by itself (although some chemicals can), but it can contribute to an inappropriate immune response.  Because phthalates cannot bind to proteins, they may serve as an enhancer to this allergic process.  This has been examined experimentally, and in one study, phthalates were administered along with ovalbumin (main protein found in egg whites) to mice.*  The production of ovalbumin-specific antibodies was significantly increased when ovalbumin and pthalates were administered together, as opposed to a much smaller antibody response when ovalbumin was given alone.  This is interesting because, as I mentioned earlier, the over-production of antibodies is what leads to an allergic response!  But now I will get back to my point above about being careful about associations, because there are some very important pieces to this study that I didn't tell you.  The enhancement of antibodies was seen at the lower doses phthalates, meaning less antibody production occurred at the high doses of phthalate administration...think about this.  So, the amount of chemical exposure is very important, (and, no, from looking at this study, it can't be determined what that dose is for humans).  Also, this study was done on mice (we are not mice), and the phthalate and egg white protein was injected under the skin.  How often do you get injections of plastic right into your body?  However, another study in which phthalates were inhaled by mice, which is a more reasonable exposure in regards to asthma, similar trends were seen.  Observations in humans show that people who are occupationally exposed to phthalates have higher rates of asthma, which is why this connection is so compelling to study experimentally.  Also, asthma and allergy rates have been increasing at remarkably similar rates since the 1960s.  I felt the need to delve into this because 1. I had never heard of this before! and 2. I love to consider all the realms of possibilities of our bodies interactions with plastic.

Autism is a disorder that has received a lot of attention lately because the number of cases has increased dramatically in the past two decades.  I wish I could give a similar introduction to the cause of autism like I did for allergies, but its cause is still unknown.  There are many theories about why we are experiencing this increase (the vaccine theory has been proven bogus), but scientists are searching for answers for its cause and increased incidence.  An association between autism and phthalate exposure was observed from a study in which pregnant mother's phthalate exposure was measured, and subsequently their children's behavior was followed when they reached age 7 to 9.  The children who had the highest in-utero exposure to phthalates (as measured from their mom's exposure during pregnancy), scored significantly poorer on social cognition, social communication, and social awareness than those who had the lowest in-utero phthalate exposure.  These results were scaled to the Autistic Spectrum Disorder scale used for the general population.  The hypothesis that there is a developmental component to autism is becoming more widely acknowledged in the current scientific arena.  Additionally, the environment is considered to play a large role in autism because genetics (or twins) explain just one-fourth of autism cases.  While this association isn't as biologically satisfying because there are so many uncontrolled factors (like, what else were the moms exposed to?), it is certainly worth more studies and observations.  I look forward to following these studies and telling you how we're coming along on solving this mystery.

*I am an animal lover, and while it makes me sad to think about animals being used in experiments, there is not yet an adequate model for studying chemical effects without them.  Humans can't be used because it would be unethical to possibly make someone sick.  The Environmental Protection Agency has been working on a computer model called ToxCast that uses computer modeling to make predictions about chemical behavior in the human body, and it is currently being validated for some new chemicals.  It will be a huge animal, time, and money-saver when computer models can be used for toxicological experiments!