Fish, EDC, the Third World, and You
Plastics have been in wide use since the 1950's. Back then, the effects of plastic on biological life were widely unknown. Today, we have a broad understanding on what exactly happens when you mix plastic with living organisms, be it fish, animals, or humans.
Plastic is a wide term to describe a variety of polymers such as PVC, nylon, polyethylene, etc. For many plastics, there exists a step to harden the polymer with a plasticizer, much like how carbon is added to rubber in the production of tires. A property of these plasticizers is hydrophobicity, which can be observed by running any plastic under the faucet and observing how the water is not absorbed, unlike cloth and other organic tissues. The plasticizers are effectively small “beads” that fill in pores scattered throughout the plastic. The smaller the “bead” of the plasticizer, the better they pack into pores without escaping. [1]
Because plasticizers are hydrophobic, they want to escape water constantly. When plastic is submerged in water, the plasticizers are struggling to stay within their pores. When subjected to UV radiation, chewing, heating, etc., they slowly release. If the plastic is swallowed, plasticizers are rapidly leaked out of the plastic into organic matter, escaping the pervasive water surrounding them. [2]
Plasticizers are commonly referred to as Endocrine-dirupting chemicals (EDC) because of how animals react to them. EDC are treated as hormones once they are inside of an animal, functioning as estrogen/androgen, or anti-estrogen/androgen. [2] If you have a perfect balance of estrogen and anti-estrogen, for example, you would not see any effects of estrogen outside of increased stress on the liver to process the artificial hormones. This balance is rarely observed in nature.
Fish are very sensitive to these EDC due to the aggressive disbursement of plasticizers in water. [3] As a result, physiological and behavioral changes are both rapid and severe. [4] Male fish are smaller, produce less sperm, are less aggressive in mating attempts, and in severe cases start to develop cyst-like eggs in the testis. Females are less likely to maintain nests, and begin to swim away from males. Intersex fish begin to be observed. [5] Hormonal release is well documented in fish, with females often releasing pheromones to influence male behavior in regards to mating (this was shown by castrated males ignoring the chemical signalers released by females). [6]
The most EDC comes from two sources: microplastics (pieces of plastic less than 5mm in diameter) and runoff from waste management/water treatment facilities. [7] In fact, the closer you are to an urban population, the more microplastics and EDC will be present in the water. [8] Even the weather effects the amount of these chemicals in the water, as there is a noticeable increase of EDC during rain and watershed. [9] The most common form of microplastic found in water is a microfiber, which is a small strand of microplastic, similar to the loops on velcro, or the padding on fleece. In fact, microfiber is so pervasive as to be in 87% of the world's drinking water, [10] with the overwhelmingly vast majority of it stemming from the third world. Greater than 90% of all plastic pollution in the world directly stems from Asia, Africa, and South America. [11]
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