Science Makes Sense-Week 24:Chemistry and Social Justice, plastics in the environment.

Several years ago, I used to travel by train in India regularly. When we stopped at a station, we would buy tea from vendors who would serve it in little clay pots that we could throw out of the window and watch it break. Now when I come to India and drink tea, there are no clay pots that are biodegradable, only plastic cups that litter the trash and get into water bodies. Milk no longer comes in glass bottles but in plastic bags. Take-out food is no longer given in leaves stitched together and wrapped up with string; it is now given in little plastic bags! In the U.S., the amount of plastic in packaging in addition to replacing glass with plastic everywhere has led to huge amounts of plastic trash getting into lakes, seas and oceans.
We already know that plastic has been man-made using polymers of different monomers to arrive at the varieties of plastic discussed last week. We will look at how humans and other animals are affected by plastic.
Residual Monomer:
Formation of long polymer chains is never perfectly stoichiometric and can be a random process. This can lead to unreacted monomers. Some monomers like formaldehyde, styrene(from take-out containers),vinyl chloride(from PVC),and bis-phenolA(from polycarbonates) are known carcinogens.(Ref.1)
Plasticizers are added to polymers to render them more flexible. Many take up space in between the polymer chain and some are small enough to diffuse and cause health problems.(Ref.1)
Endocrine disrupters:
Many of the monomers have been found to be physiologically active. This is because they mimic the action of hormones or other signaling molecules. This is done by probably fitting and binding on to the specialized receptor sites in tissues. The health effects on adults is still not clear,but there is definite concern of its effects on fetuses.(Ref.1)
Decomposition problems:
Most polymers are not biodegradable, particularly in the anaerobic (absence of free oxygen) conditions of landfills. However, decomposition products here could combine with rainwater and contaminate nearby streams and water supplies.
Plastics with fluorochlorcarbons break down into perfluoro octane which damages aquatic animals.(Ref.1)
Effects on living beings:
Perhaps the most devastating effects has been on animals and birds and sea life. Since we know that most of the plastic trash gets into the water bodies, all life on water and near the shore are adversely affected by plastic. Animals and birds consume the plastic as food and die. Many big fish get entangled in big plastic sheets in the sea and get choked. Add to that the health hazards that animals face just like humans.(Ref.1)
Recycling is one solution, but the United States is dragging its feet to get some federal legislation passed to make it a national movement. Most countries in Europe have a viable recycling plan having bins in the neighborhood for all kinds of plastic packaging to be recycled.
When glass was replaced by plastic most of us were relieved at the light, non-brittle nature of plastic, the convenience of using trash bags that did not leak and the lunches that were so neatly packed in little plastic bags. Little did we worry about how it would impact us and other life forms around us. Today, in developing countries like India, plastic trash is everywhere, choking roadsides and canals of water. In countries like the U.S., though plastic trash is not so visible, its adverse effect on human and animal life is a daily reminder that more should be done to look for alternatives. Meanwhile, let us start cleaning up the mess created by this polymer invasion.

Activities for Middle School Teachers:
Let students go to a supermarket and list the number of products where plastic is used. Are all plastic containers the same? How are they classified? What is recyclable? (Look at Nuggets of Information also for some help)
Students should look at their own neighborhoods to see if plastic trash is around. How about in local water bodies?
Take the students to recycling centers and find out how and which kinds of plastic are recycled. Attend special green festivals where plastic is reused in innovative ways.
Teachers and Students! Do you travel for vacations to beaches in, say, Mexico, Thailand, India? When you stay at hotels/ resorts find out what happens to all the plastic trash used by tourists. Are there viable recycling programs in these countries? How are we as US tourists impacting world use of plastic? What are our ethical responsibilities?
Encourage yourself and students to use cloth bags when shopping anywhere; avoid plastic bags as much as possible. Recycle plastic bags at suitable supermarkets. Use glass instead of plastic to store food and spices.

Nuggets of Information:
Each year 8 million tons/16.6 billion pounds/7.2 billion kilograms of plastic enters the ocean. Each day two Empire Buildings (New York)full of plastic washes into the ocean. A 21-year old Dutch scientist named Boyan Slat is getting ready to clean the Pacific Ocean of its plastic trash. (Ref.2)
In India,you are charged for using plastic bags in several places where you shop.
PDFA, a monomer from which Teflon is made, was the subject of a 2004 lawsuit against DuPont when ground water was contaminated. (Ref.1)
Bis phenol A, commonly known as BPA, (actually two benzene rings with hydroxyl groups connected by a hydrocarbon link) has been found mainly in certain kinds of plastics used to make water bottles, baby bottles, sealants, medical devices and sports equipment to name a few. This kind of plastic has been shown to be endocrine- disruptors; babies and young children are especially vulnerable to this health hazard. (Ref.3)
The European Union(EU) has a far better record at recycling plastic than the United States(US);EU recycles 25%, while the US recycles only 10%.(Ref.4)
There are seven different codes for plastic found as a number and some letters at the bottom of plastic containers:
1. Coded number 1 is polyethylene terphthalate or PET/PETE. This high-impact plastic is used for beverage bottles, food jars and frozen food trays. Recycled PET is reused as bottles, as well as fleece jackets, to name a few uses.
2. Plastic code 2 is made out of high density polyethylene or HDPE which is used in milk/juice/detergent/bleach/cosmetic bottles and is recycled into garden products and buckets.
3.Code 3 is PVC-polyvinyl chloride and is used for bedding, medical equipment, pipes, etc. Recycled it is used as decking, carpet backing and for traffic cones.
4.Code number 4 is used for low density polyethylene, LDPE and is used a lot for garbage bags,bread bags and for squeeze bottles. Recycled it is used for shipping envelopes, garbage can liners, etc.
5.Number 5 plastics is made from polypropylene, or PP for yogurt, margarine, syrup containers as well as medicine bottle and auto parts. It is recycled to make garden rakes, storage bins, brooms and brushes.
6.Polystyrene or PS is coded number 6. These are short shelf-life products like take-out containers, cutlery and packing peanuts for example. This is recycled into insulation, licence plate frames and plastic moldings.
7.Code 7 is layered resins and composite materials that are very difficult to recycle and used for baking bags, ketchup bottles. It also contains BPA that is toxic: number 7 is to be avoided at all costs.
(Ref. 5)
Japan has been most successful in recycling plastics. In 2010, Japan recycled 77% of its plastic waste. Japan recycles 72% of PET bottles, while Europe recycles 48% and US is a dismal third with 29% of PET bottles recycled. (Ref.6)
‘Micro beads’ is the latest scourge in plastic contamination. This is being used mainly by the cosmetic industry and touted as a great face cleanser, but these little plastic pieces are entering our water bodies and contaminating and killing aquatic life in our seas and oceans.(Ref.7)
The latest news from January of 2016 from Germany is that several dead sperm whales washed up on the shores in Germany and a lot of plastic was found in their stomachs.


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2 Responses to “Science Makes Sense-Week 24:Chemistry and Social Justice, plastics in the environment.”

  1. Chaib, Hadda Says:

    Hello professor,

    How are you? I really enjoy your informative blogs. I feel like I am in the classroom. I am wandering if you put all of your blogs in book and have it available for middle school students. They are really informative topics. I like the way you always start you blog. You introduce each topic with a real life experience. This is why I think it would be great idea to have these valuable information available for students.

    I hope everything is well with you and your family. Please let me know when you come and visit Chicago. I would love to see you :).

    Best regards,


    On Sun, Feb 14, 2016 at 9:06 AM, Chobhis Blog wrote:

    > chobhi posted: “Several years ago, I used to travel by train in India > regularly. When we stopped at a station, we would buy tea from vendors who > would serve it in little clay pots that we could throw out of the window > and watch it break. Now when I come to India and dr” >

    • chobhi Says:

      Dear Hadda, so very glad that my posts are useful. Funny you should talk about publishing; I do wish to do that once I finish some more of these and look around for a publisher. We will definitely keep in touch, once I come to Chicago!

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