Thursday, December 19, 2013

Exfoliating Beads Contaminating the Earth’s Waters

face scrub with polyethylene beads
While soaking in the bathtub I realized that the facial cleanser that I have used for years and leaves my skin feeling amazing has polyethylene listed as an ingredient. I read the ingredient list because a study at the University of Auckland in New Zealand found that the majority of facial cleansers, many tooth pastes, hand creams, body wash now contain exfoliating beads made of polyethylene making it likely that I was using cleansing products that contain tiny beads of polyethylene. These bits of polyethylene plastic are too small to be captured by wastewater treatment plants filtration systems that were not designed to address such small contaminants. So, after using an exfoliating scrub face or body wash, these microplastics beads flow down the drain and through waste water treatment plant and end up in the rivers, bays and oceans, where they may become a hazard to marine life. It seems like common sense that the polyethylene beads float and their scrubbing surfaces pick up contaminants which are consumed by marine life. There seems to be no information on the fate of the polyethylene beads in septic systems whether they remain in the leach field or enter the groundwater. The scientific community calls these polyethylene beads microplastics.

The National Oceanic and Atmospheric Administration, NOAA, has a Marin Debris Program that has been leading efforts within NOAA on this emerging issue of microplastics in the earth’s waters, recently discovering a high concentration in the Great Lakes. NOAA defines microplastics as plastic pieces approximately the size of a pencil eraser or smaller. They are working in partnership with the University of Washington Tacoma to standardized methods for collecting samples of microplastics from sediment, sand, and surface water so the problem can be fully quantified. While it seems likely that nearly all of the plastic that has ever been released to the waters of the earth still appears as polymers, very little or any plastic fully degrades in the earth’s water environments, without systematic and effective ways to sample we cannot know for sure. Estimates of macro- and microplastics in the oceans, made by scientists and environmental groups are highly uncertain due to the lack of consistent, verified sampling and analytical methods.

No research has examined microplastics in deep ocean sediments, and most studies have only scooped samples from the surface of the ocean and lakes looking for plastics. Recent work at the State University of New York at Fredonia has confirmed that microplastic beads pass through waste water treatment systems into the Great Lakes introducing the possibility that microplastics are in the source water supplies for the drinking water systems. Though many plastics are buoyant and float, many other factors play a role in the “life cycle” of a piece of plastic in the ocean, lake or river. Sinking may occur due to the accumulation of biological material on the surface of the beads, and plastics may eventually settle into sediments. The microplastics beads fouled with biological material may be eaten by marine life, the biofilm consumed, and the remaining undigested plastic packaged into fecal matter.

In truth, little is really known and much research needs to be done. It is difficult to determine how large an impact microplastics might have as there is a paucity of data linking microplastic debris to demonstrated impacts on the marine environment. Data that conclusively demonstrates negative impacts of microplastics on the marine environment is critical gap that needs to be addressed. Research into collection methods, species impacts, and removal methods should focus on four important areas:
  1. Documenting microplastics in the marine environment, 
  2. Determining the lifecycle of these particles (and, therefore, their likely buildup in the future), 
  3. Demonstrating ingestion by marine organisms. 
  4. Impacts of microplastics to marine organisms and the environment. The ability for plastics to transport contaminants has been documented, but the specifics of sorption and leaching are not fully understood.
It is difficult to determine or even reasonably estimate how large an impact microplastic bead might have on the environment. They can either be a source of pollutants or a location where pollutants can adhere and concentrate for the oceans, lakes and rivers and first we must determine how much is manufactured. So, the first step is an inventory of microplastic bead production and uses has to be completed. Surprisingly, little is known about the chemical composition and rates of leaching of integral plastic components in seawater and freshwater so it is impossible to estimate whether the plasticizers or flame retardants used in the manufacture of polyethylene will be released to the earth’s waters.

NOAA is funding research to identify marine species that would likely be most vulnerable to microplastic beads. Possible effects include three general areas: (1) physical blockage or damage of feeding appendages or digestive tracts, (2) leaching of plastic component chemicals into organisms after digestion, and (3) ingestion and accumulation of absorbed chemicals by the organism. All of these effects require that the microplastic beads be ingested, so first scientists need to identify the species most likely to ingest these particles. There is much work to be done; nonetheless, maybe we should only use exfoliating scrubs with biodegradable beads until more is known. I am afraid that I will have to change face scrubs and I will have to check the label of all my other products.

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