Author Archives: taylor kim

This is the Last Straw (literally)

Posted on November 5, 2018 | 1 comment

Plastic straws (image courtesy of Wikimedia Commons)

I’m sure you’re all aware of the most recent environmental movement: elimination of single-use plastic straws. From Starbucks to McDonald’s, major companies around the world are pledging to ditch plastic straws. Although they are small, their effects are mighty. Close to 500 million plastic straws are thrown away every day in the United States. Some end up in landfills, but a large number become plastic trash in our oceans. The solution was to introduce “sippy cup” plastic lids and alternative-material straws. This is a huge win for anti-straw advocates, but what are the true environmental effects?

On one side, plastic straws should stay as their ban results in an insignificant decrease of plastic waste in our oceans. According to a recent report by environmental group Better Alternatives Now (BAN), plastic straws comprised only 7% of plastic items found along the California coastline, compared to plastic bags at 9% or plastic bottle caps at 17%. When taken by weight, a report by Jambeck Research Group places plastic straws at only 0.03% of aggregate plastic in the oceans themselves. Majority of plastic waste found in oceans actually comes from fishing nets.

Plastic waste gathered at a shoreline (Image courtesy of Pixabay)

Furthermore, the BAN report also noted that products labeled as biodegradable or compostable plastics are not, in fact, actually biodegradable in an earth or ocean environment. Companies moving towards biodegradable plastic straws are not having any actual impact on ocean plastics.

Chemical structure of the plastic polymer, polypropylene (Image courtesy of Wikimedia Commons)

In support of the plastic straw ban, companies have revealed the benefits to their alternative solutions. Starbucks made it known that their new “sippy cup” lid is made from polypropylene, a commonly-accepted recyclable plastic that can be captured in recycling infrastructure. This was an almost impossible task to accomplish with straws, which are too small and lightweight to be captured.

The lives of marine animals, such as sea turtles, will also be protected by the straw ban. Small plastic straws can easily get lodged in their airways, causing them pain and discomfort, and in extreme cases, death.

Both sides of the plastic straw ban have valid arguments. Although only a small one, I believe it is a step in the right direction. This movement will hopefully be the gateway to banning more plastics which will hopefully lead us to a future of plastic-free oceans and landfills. So, are you pro-straw?

1 Comment

Posted in News

Tagged , , , , , , ,

Can Cleaner Pig Poop End Global Warming?

Posted on October 15, 2018 | 2 comments

Pigs – photo from Wikimedia Commons

In short, no. However, it may be able to reduce the carbon footprint of the pork industry. You’re probably wondering what in the world pig manure has to do with climate change. Trust me, I was in the same position before embarking on some research of my own.

Piles of pig manure – photo from Geograph

Apparently pigs lack 3 important enzymes needed to digest the nitrogen and phosphorus in their feed. Nitrogen oxide, a dangerous climate pollutant, is thus released from the manure of these animals. Although it only makes up about 6% of all US greenhouse gas emissions, it can trap 300 times as much heat as carbon dioxide, according to EPA. Reducing nitrous oxide emissions could play a major role in reversing the effects of global warming.

2016 U.S. nitrous oxide emission, by source – Data courtesy of EPA

5% of nitrous oxide emissions are a result of manure. To tackle this source, scientists began looking into finding a way to enhance the digestion of feed in pigs in order to reduce the excretion of dangerous pollutants. Xianwei Zhang and colleagues at the South China Agricultural University considered genetically modifying their pigs to be better able to digest these nutrients. The findings, which were published in eLife, proved that the new generation of transgenic pigs did in fact release less nitrogen.

So how exactly were the pigs genetically engineered?

Firstly, the scientists looked at what pigs lacked to know what to modify. The enzymes that pigs needed for the digestion of nitrogen were b-glucanase, xylanase and phytase. Zhang and researchers attempted introducing genes required to make these enzymes into the genomes of the pigs by a process called Somatic Cell Nuclear Transfer, or more simply, cloning. The image to the left outlines the key steps.

Next, they determined how to make the digestion process as efficient as possible. By expressing the 3 bacterial enzymes in the animals’ salivary glands, they were able to ensure that digestion began in the mouth.

Now comes the unpleasant part. In order to test their methods, the team was required to measure nutrient levels in the pigs’ manure and urine. That’s right, they studied poop!

As predicted, fecal nitrogen outputs in the modified pigs were reduced by as much as 45.8%. The scientists also noted that due to an increase in nutrient digestion, the pigs were becoming fully grown a month earlier than their non-genetically modified peers.

By growing fast, requiring less food and producing fewer pollutants, the pigs developed by Zhang and her team could lead to a win-win situation for farmers and the environment. Now imagine the benefits if we apply similar methods to major sources of agricultural greenhouse gas emissions, such as cows and sheep!

2 Comments

Posted in News

Tagged , , , , , , , , , ,

Is BPA-Free Safe for Me?

Posted on September 17, 2018 | 1 comment

I often find myself gravitating towards products that have labels such as “organic”, “cruelty-free”, “free-range”, etc. stuck to their packaging. It’s comforting to know I am opting for a product that is beneficial to either my health, the environment, or both. That’s why when I’m faced with the option to purchase a water bottle that is BPA-free, versus one that is not, 10 times out of 10 I buy the former. For years now I believed this choice was protecting me from the harmful effects of bisphenol A, a chemical known to disrupt reproduction in mice. Much to my surprise, this belief was shattered by a recent article in Current Biology that revealed that the replacement bisphenols are potentially just as harmful.

BPA-free plastic water bottles – photo from Pixabay

Patricia Hunt, a biologist at Washington State University who first discovered the damaging effects of BPA 20 years ago, has uncovered data that mirrors those findings. This new study shows that BPS, a replacement bisphenol, is causing abnormalities in the eggs and sperm of mice. Essentially, BPA-free plastics could still be causing the same adverse effects in humans that led us to ban BPA so many years ago.

The findings were uncovered much in the same way as the BPA discovery decades ago. While conducting unrelated research, Hunt noticed changes in the data collected from her lab mice. Specifically, she found abnormalities in their eggs and low sperm counts. “Given our previous experience with BPA leaching from polycarbonate cages and water bottles,” states Hunt, “damaged materials were an obvious suspect”.

Upon analysis of the plastic cages that the mice were being kept in, Hunt and her team discovered that the inner surfaces to which the mice were being exposed had traces of BPS. The compound, which has replaced BPA in many household items, was being released from the plastic from everyday wear and tear. Notice the similarities between the two chemicals in the images below.

Chemical structure of BPA – photo from Wikimedia Commons

Chemical structure of BPS – photo from Wikimedia Commons

To further investigate the issue, Hunt designed experimental studies in which mice were exposed to several replacement bisphenols. The effects were observed by looking at the number of DNA points where chromosomes had been reshuffled, known as MLH1 foci. This data was telling as MLH1 foci is indicative of the degree of abnormality. Females who were found to have high numbers of MLH1 foci were producing abnormal eggs. On the other hand, males who had low numbers experienced an increase in cell death during sperm creation.

The thought that plastic, a material that we use daily, could be affecting our reproductive health is extremely concerning. The results from Hunt’s most recent studies are remarkably similar to those seen years ago with BPA and raise the question if bisphenols as a class should be eliminated. I hope an alternative replacement in plastics will soon be discovered so that we can still enjoy the diverse benefits of this material.

1 Comment

Posted in News, Uncategorized

Tagged , , , , , , , ,