All the trash unfit to eat: Oceanic plastic debris as a human health concern

This week I had the opportunity to meet Captain Charlie Moore, the sailor and oceanographer, credited with discovering in 1997 the North Pacific Gyre, the accumulation of plastic debris floating between California and Hawaii. Some 20 years later Moore presented findings of a longitudinal study at the Southern California meeting of the Society of Toxicology and Environmental Chemistry (SETAC).

Sacred Heart Chapel at sunrise. Photo by R. Hartsook

This regional SETAC meeting (April 12-13, 2018) was hosted by Loyola Marymount University (LMU). The presence of a scientific conference at a Jesuit university reminded me of something Carl Sagan once wrote:

The notion that science and spirituality are somehow mutually exclusive does a disservice to both. 

A presentation on sustainability at LMU by Vice President of Auxiliary Management Raymond Dennis opened with reference to Laudato Si, Pope Francis’ encyclical on the environment and quickly moved to the science (and dollars and cents) of sustainability at LMU. For example, the food service at LMU diverts pre- and post-consumer organic waste to biofeed and in doing so reduced their average 100 tons of solid waste per semester to 30 tons. The peaceful co-existence of science with faith was reassuring. Dennis spoke with reverence about the need to care for the environment as an extension of faith.

It was with the same tone of reverence that Charlie Moore spoke of the oceans. A sailor by training, Moore has conducted detailed research on trends in the debris in the North Pacific Gyre. He was quick to acknowledge that the lack of availability of robust methods to reliably sample the gyre limit the value of his 15-year time series assessing trends in plastic marine debris. For example, the gyre has a moving center of accumulation, so sampling from the same geographical location (as was done in his time series) does not tell us about the behavior of the center of accumulation. He was one of several presenters who highlighted methodological limitations hampering research more than 20 years after the discovery of the gyre.

29011562 - modern urban wastewater treatment plant.Perhaps one would argue that sampling an area so large as the Pacific is unavoidably complicated. Well, it turns out that microplastic sampling methods for something as geographically constrained and easily accessible as wastewater treatment are still lacking. USEPA Region 9 scientist Anna-Marie Cook highlighted the need for basic science on the topic as there are no reliable data on how much plastic escapes wastewater treatment (you may see estimates floating around—no pun intended—but Cook asserts that these are unsupported). She is working on methods to reliably measure microplastics in wastewater influent and effluent.

Some will find the images of seabirds and marine life filled with trash moving, but not moving enough to curtail the purchase of products in plastic containers. Changes in consumer behavior are motivated by either risks or incentives about which consumers care.

20857864_xl.jpgWhile I find compelling the argument that fish from fertile coastal waters represent a significant portion of dietary protein and economic security for the developing world and that microplastics imperil these fish populations, for purchasers of certified sustainable wild-caught salmon, these concerns may seem far removed. This is not so very far removed since plastic pollution is ubiquitous, such that it is impossible to source fish guaranteed free of plastic pollution.

To the consumer, the health impacts of these microplastics may not be apparent since most lay people think of plastic as an inert substance. On the contrary, the most chilling part of the SoCal SETAC meeting were data presented by multiple credible scientists, including scientists from USEPA Region 9, demonstrating unequivocally that plastic particles behave like passive samplers and basically soak up persistent pollutants including PCBs and flame retardants.

In fact, Anna-Marie Cook stated that the contaminant concentration on the surface of a microplastic particle is often one thousand to one million times higher than the concentration of those contaminants in the water. These persistent chemicals, with proven human health impacts, can enter the food web and potentially bioaccumulate and biomagnify. While we must be cautious about overstating the public health impact of this vector of exposure, it is a non-zero exposure and warrants further consideration.

This got me to thinking, what are the solutions to keeping plastic out of the ocean?

  • Don’t buy it (easier said than done)
    • At about 10%, rates of plastic recycling have been stagnant over the past 4 decades (this per Anna-Marie Cook); you may sort it, but that doesn’t mean the plastic gets re-used. Much of what is sorted for recycling ends up as landfill.
  • Advocate for solutions that keep plastic waste out of waterways
    • Waste-to-energy, embraced as a pragmatic solution in Sweden, continues to be a contentious issue in the US (the arguments against to waste-to-energy are not entirely convincing, and a topic for another day).

The issue of marine plastic debris is not an abstract environmental issue but is better likened to undiagnosed cancer—ignoring it will not improve the prognosis.

Until next time.  -Renee


Fumifugium is the blog of Renee Hartsook Ph.D. DABT, consulting toxicologist and owner of Takmos LLC.