Dr Abe V Rotor
No digestive enzyme – not even gastric acid – is powerful to break down plastics, no matter how long the material is subjected to this natural solvent.
The goat was pregnant for too long and was getting thin the owner sent for the butcher.
Guess what we discovered? The bloated stomach was stuffed with plastics – pieces of containers, wrapping materials and grocery bags. One cannot imagine why the animal devoured plastics instead of grass other than due to hunger. After all, goats are not choosy when it comes to food. Outside the wide range of plant species they can eat, since they are omnivorous, they yearn for almost anything sweet, salty, oily or spicy.
Curiously, an inventory was made from the animal’s stomach. Found in it there were cellophane used for sweets like bocayo, peanut butter, and candies, thin plastic bags for retailing bagoong alamang, patis, toyo, cooking oil, ice drop and the like. The largest are grocery convenient bags for meats, fish, soft drinks, fruit juices and cooked food. Some of these materials still bear traces of the product trade names, indicating recent ingestion. Plastics earlier ingested were discolored, but nonetheless are undissolved and intact. As the stomach twists and turns, the larger plastic materials envelop the smaller ones, forming a mass stuck up in the rumen (or large first compartment of the stomach) like clothes in a overloaded washing machine.
The stomach of ruminants is designed to store large amounts of food. The food is consumed rapidly with a minimum of chewing, before it is swallowed. This reduces grazing time while it enhances large intake. Then when the animal is resting, the raw ingesta is brought out for re-mastication. At this time, digestive enzymes are mixed in with food before final digestion.
The stomach muscles incessantly contracting and squeezing, in a process called peristalsis (successive waves of involuntary contraction along the walls of the intestine, forcing the contents onward). Digestive enzymes dissolve solid materials into pulp (chyme), which is a thick soup material which later goes to the small intestine. Here, the nutrients are assimilated by tiny and numerous, tiny finger-like protrusions called villi. The remaining contents then move to the large intestines, where they are retained for a while before being excreted as feces.
Why does the stomach retain the plastic materials?
We know that goats and other ruminant animals like sheep, cattle, zebra and gazelle, have very efficient digestive systems. This is needed for them to subsist on more than just high-fiber food such as grass and roughage. Their chambered stomachs retain food much longer than man can, or fowls, and pigs. This explains why the excreta of ruminants yields well digested fiber. This is not the case with the excreta of animals with simple digestive systems such as pigs. Birds and chicken although they break down shells and stones in their gizzards, cannot fully digest cellulose. Perhaps the only creature, superior to ruminants in cellulose digestion, is the termite. Termites have living protozoa in their stomachs that break down wood cellulose even in its tough form, lignin. Without this symbiont, termites will certainly starve and die. There has been no known successful experiment, however, to determine whether termites can digest plastics.
The implication is that no digestive enzyme, not even gastric acid, is powerful enough to break down the cellulose in plastics. This is classical proof of the non-biodegradability of plastics.
The question is asked: Can’t ruminants eliminate unwanted materials in their digestive system either by regurgitation or excretion? The answer is no. In the first place the movement of the stomach and its chambers (rumen, reticulum and omasum) are not governed by the central nervous system. The mechanism of rumination is involuntary. It is the coarseness of the feed that stimulates the walls of the rumen to contract so that the material is brought out for re-mastication. Animals, which feed on soft and non-fibrous diet like alfalfa, ruminate less than those that depend on roughage.
Plastics Camouflage Appetite
It is likely that the plastic materials line the surface of the rumen in a way that produces insufficient stimulation to expel the ingesta for re-mastication. Another effect is that the animal experiences false fullness, camouflaging true appetite. This means that because the animal is not hungry, it eats less, consequently, becoming malnourished. Thus, the goat that ate plastic was emaciated, yet had a bloated stomach. Yet this does not discount the possibility of slow poisoning due to the slow disintegration of secondary metabolites.
The first completely synthetic man-made plastic, Bakelite, does not burn, melt or dissolve under ordinary solvents. As an additive, it makes almost any material strong, durable and light.
What is plastic? How are plastics differentiated?
1. The first plastic was made by Alexander Parkes in 1862, after whom it was named: Parkesine. Actually it was an organic material derived from cellulose. Once heated, it could be molded, retaining its shape when cooled.
Because of its high cost of production it was shelved until the later part of the 19th century when celluloid made a debut as replacement for ivory in making of billiard balls. To prevent the explosion of the highly volatile celluloid, camphor was added leading to the development of thermoplastics.
2. Soon, the first completely synthetic man-made plastic was formulated by a New York chemist, Leo Baekeland, hence the name Bakelite. This material does not burn, boil, melt, or dissolve under any commonly available acid or solvent. It also retains its shape. Bakelite could be added to almost any material, making the new substance more durable, light, heat-resistant and shatterproof. War machinery and automobile manufacturing made use of this new product to great advantage.
3. Other forms of plastics were then discovered. These include rayon (man-made silk), and cellophane (the first glass-clear, flexible and waterproof plastic). These materials have many uses today.
4. By 1920, the “plastic craze” spread out. Du Pont, one of the leaders of the industry developed nylon, replacing animal hair in toothbrushes. By 1940, the world saw the development of acrylic, polyethylene, and many more polymers, which replaced natural materials such as cotton, fiber, wood and steel.
5. DuPont later introduced Teflon, favored for lining cooking utensils for its acid and heat resistant while its non-stick properties make the utensils easy to clean.
6. Dow, another plastic manufacturer, on the other hand, came up with polyvinylidene chloride, better known as “Saran”, a perfect material for food packaging and storage.
7. Polyethylene, introduced in 1933, is currently the largest volume plastic in the world for making soda and milk bottles, grocery bags, and plastic food storage containers. This is the kind of plastic the goat ate and which made her sick.
8. There is virtually no end to the discovery of other forms of plastics. We have plastic putty developed by Velcro. This material is similar to rubber, but has a 25 percent higher rebound power. Its property of not being able to maintain a constant shape is compensated by its high flexibility, stretching many times its length without tearing. Initially, it was used in the manufacture of toys, but now many potential uses are seen.
A World Without Plastics?
Today’s world is incomprehensible without plastics. Plastics contribute to our health, safety and peace of mind. They are part of our dwellings, cars, toys, appliances, even body parts such as heart valves and prosthetics. There are countless uses in all aspects of our lives.
On the other hand, the biggest dilemma with plastics is its proper disposal. It has become a major waste handling challenge all over the world. While we see its virtually endless uses, we are also witness to its accumulation exacerbated by its inability to biodegrade. As a result, its rate of accumulation is alarmingly enhanced, creating an issue of concern to environmentalists, and citizens of the world.
In a recent field trip along the coast of Morong, Bataan, in the Philippines, students from the UST College of Pharmacy were surprised to see plastic material strewn by waves along the shore. A cursory examination revealed the following materials:
1. Plastic sack which has replaced the jute or gummy sack
2. Nylon rope and filament, which have replaced Manila hemp and cotton threads. Filament is used for fish net.
3. Plastic simulated leather used in shoes, canvas and bags. There are other kinds of artificial leather.
4. Styropore for packing and containers, replacing banana leaves, straw and paper.
5. Foam mattresses, slippers and furniture. Natural sponge is now a rare commodity. Foam has replaced coconut coir and kapok.
6. Plastic bottles, jars and containers. Glass is still the best material when it comes to food storage.
7. Plastic sachets, bags and wrappers have largely taken over the use of paper and cardboard.
These plastic materials are familiar to us. We see them at home and on store shelves. They are evidences of our modern, throw-away culture.
Trapped Fish Fry in Plastic
While gathering the garbage to help clean up the shore, the author’s students found trapped fish fry in plastic bags. Wanting to find out how this happened, we looked for clues. The plastic bags, flushed down the river, or thrown by unscrupulous residents and promenaders became homes for young, marine species. Since these materials are not edible seaweeds or seagrass, they become entrapments to the fry. Causing their death through starvation and asphyxiation.
We have seen plastic materials stuck at the bottom of reefs preventing juvenile seaweeds from developing. Plastics also trap the polyps of corals, and microsopic zooplankton eliminating a major food source for marine life.
That evening, along the shores of Morong, we asked ourselves what each can do to rid the shores of plastics. While we reflected in silence, the tranquil waves washed ashore a plastic bottle.
Here are things we can do with plastics.
1. Re-use plastic bags and bottles at home. Remember that plastics are durable. Be sure to clean them properly before using.
2. Gather plastic bottles and unserviceable plastic wares for recycling. Arrange with cart pushers, or your nearest junk shop for their regular collection. Do not attempt to re-melt plastics. The process is not as simple as you think. Don’t burn to dispose them, either. Burning plastics emits smoke and fumes deleterious to health.
3. Do not use plastic if you can help it. Use paper or glass containers. This is also advantageous to your health. Do not use plastic containers for soft drinks, vinegar, salt, patis, toyo. Strong solvents tend to chemically alter in the presence of plastics. Studies that show that some plastics that are carcinogenic.
4. Keep plastic materials away from your bedroom. As plastics age, they emit gaseous substances which may cause allergy, asthma and other ailments when inhaled.
5. Patronize products that use non-plastic containers, wrappers, bags and utensils.
6. Be part of a community environmental project. Attend seminars and workshops that talk about the environment. Read about ecology; learn to be a leader in this area; know about re-cycling, values formation, and the like. Be an ecologist yourself.
Nata Laminate – Potential Plastic Substitute
Now, this one is for the Guinness Book of Records. Shoes now are made from nata de coco. At St. Paul College QC, Dr. Anselmo S. Cabigan and his advisee Amparo Arambulo developed shoes made from nata laminate. The laminate is actually compressed nata de coco, dried and layered into ply, then subjected to the usual tanning procedure. It is cut and made into shoe soles, actually worn by students quality test. Nata laminate is stronger than leather. It gives a good finish and it looks like leather.
In another research, nata was made into surgical thread. Since nata is a natural product (a capsule of the bacterium, Leuconostoc mesenteroides), it is soluble. It may be a good substitute for expensive commercial absorbable surgical threads.
Nata laminate is also a potential substitute for special paper, such as sheepskin, and an exotic material in making wallets, bags and belts. Unlike plastic, nata laminate is biodegradable. It also offers to save endangered animals from being butchered for skin.
The case of the goat that ate plastic, and fish fry trapped in a plastic bag can spur us to develop a second generation of biodegradable plastics. This is the essence of good stewarship of this planet, for our own good, as well as for those who will follow us.
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