Two different scientific papers caught my eye this past week. Neither involve research conducted in the Pacific Northwest, but both are worth reviewing in light of the fish consumption debate raging in Washington right now. The first is an upcoming article by a group of Spanish researchers in the Proceedings of the National Academy of Sciences on the amount of plastic pollution in the world’s oceans. The second is research by USGS scientists on mercury concentrations in fish in four lakes in Voyageurs National Park in Minnesota.
How do these two studies relate to Washington’s efforts to revise its water quality standards to account for greater fish consumption rates of various populations in the state? Both studies highlight the difficulty of reducing toxics in fish using the regulatory scheme of the Clean Water Act. As I’ve written in the past, I am skeptical that lowering water quality standards for toxics by increasing the fish consumption rate used in deriving those standards will result in any measurable change or environmental benefit. This is because, for many of the contaminants that are of concern, we’ve reached the point in regulating end-of-pipe and non point sources of those contaminants where revising water quality standards downward won’t reduce toxics in fish because many of those toxics are no longer coming from regulated sources.
The study on plastics in the Pacific emphasizes this point for organic contaminants in salmon, one of the species of fish often referred to as “contaminated” in the rhetoric that is flying around the fish consumption debate (but the one species that most clearly is not impacted by local water quality conditions because of the time spent growing in the open ocean). The researchers modeled fluxes of plastics to the world’s oceans and then compared the amount of plastics thought to be entering the world’s oceans to the amount observed in five subtropical gyres or convergence zones where the plastic accumulates. What the researchers documented is a large amount of “missing” plastic, i.e., what was calculated to be entering the oceans did not match what was observed. The researchers concluded that the fate of this plastic is unknown, but one hypothesis the researchers put forth in the paper is the possibility that plastics are rapidly nan0-fragmented in the oceans, where those nano-fragments are then integrated into the ocean’s foodweb.
How does this relate to toxics in salmon in the Pacific Northwest?
If it is true that small pieces of plastics are entering the foodweb in the open ocean, these nano-particles of plastics likely act like as sponges for organic contaminants in ocean surface waters, and could effectively concentrate contaminants such as PCBs into the foodweb. Salmon would pick up organic contaminants such as PCBs in the open ocean, and then return to home waters in the Pacific Northwest, to be caught and consumed by Washington residents. PCBs are one of the contaminants of concern driving the current revisions to the state’s Water Quality Standards, and this study highlights the potential complexities surrounding how toxics such as PCBs get into fish. Washington on its own is likely unable to regulate plastics in the world’s oceans–this is something that needs international attention.
The second study provides important scientific information regarding how mercury ends up in fish, and also highlights the regulatory challenge of regulating water quality with the goal of reducing toxic concentrations in fish. Like PCBs, mercury is one of four contaminants of primary concern with respect to Ecology’s current water quality standard revisions, although Ecology appears ready to defer actions regarding mercury in the current rulemaking. The USGS research involved investigating how four lakes responded to a 32-48% decrease in atmospheric deposition of mercury from 1998-2012. Two of the four lakes had decreases in mercury concentrations in surface waters over the same period, and also saw decreases in methylmercury in yellow perch. One of the lakes had a significant increase in mercury in surface waters and fish over the same period, and the fourth lake had no significant trends.
Importantly, this study looked at atmospheric deposition of mercury not fluxes from terrestrial sources, and involved lakes not impacted by other anthropogenic sources. Still, there are a few takeways from the work by the USGS in Minnesota, one being the importance of atmospheric deposition of mercury in influencing fish tissue concentrations for some waterbodies. This is a phenomenon I’d expect to hold true even in areas where there are fluxes of mercury from industrial sources because of the labile nature of atmospheric mercury, i.e, the mercury coming from the atmosphere is likely the most bioavailable form of mercury in a waterbody and the most likely source to be methylated and accumulated in fish. Another takeaway is the importance of watershed and ecosystem scale dynamics influencing fish tissue concentrations–the lake that had no trends over the study period was known to be influenced by forest fires and beaver activity.
These types of dynamics highlight why the current fish consumption rate debate is a difficult one for Ecology and Governor Inslee to navigate. It is not–as some have said–as simple as lowering water quality standards and seeing a resulting decrease in cancer risk to high fish consuming populations. It is not even a “business versus the environment” debate because these types of dynamics in terms of sources of toxics to fish are becoming the norm, not the exception, and these pathways of toxics to fish are not the pathways regulated by the Clean Water Act. It is not, in my mind, a debate about “acceptable” cancer risk because the use of a higher excess cancer risk in calculating water quality standards is legally defensible, and likely doesn’t mean a thing in terms of actual cancer risk to many populations because of how toxics get into fish.
What this debate is about is adjusting our regulatory approaches to account for modern environmental issues. Applying the Clean Water Act framework to this issue just won’t work for many of the contaminants of concern–but if we proceed down that road anyways, the cost to society will be high, with little or no measurable environmental benefit. Governor Inslee prides himself on being a very “green” governor. To be true to that self-characterization, once the fish consumption debate is resolved (likely in courts) he should step back and rethink how to address toxics in fish, and potentially lead the way nationally in crafting a new regulatory scheme that accounts for the modern challenges of reducing toxics in fish, rather than the application of a forty year old regulatory scheme that was never designed to account for the issues we are wrestling with today.