Questions, questions, there are always questions. The big question about my review of the Environmental Protection Agency’s (EPA) January 2016 “National Coastal Condition Assessment 2010” report was “how did the EPA determine the majority of coastal fish in the United States were in fair to poor condition?” My last blog post (if you didn’t catch it, here’s the link https://waterblogger.org/water-quality/ocean-condition/) said EPA rated the majority of fish in coastal waters as fair (26.4 % of fish) to poor (49 % of fish) due to the amount of selenium in the fish tissue. It is a fair question about what constitutes such a rating. So I went back to EPA’s technical report which provides all the methodologies for the data produced during the study. It was also released in January 2016, as a companion piece to the “National Coastal Condition Assessment 2010” report.

EPA has been using a standard process for examining toxicity in fish for the two decades they have been producing reports on coastal conditions. The method used examines the whole body tissue of a fish. When I used to work on ecological risk assessments, we referred to this method as the bassamatic. EPA of course refers to the process as homogenization. Basically you put the fish in a blender or other sort of grinder. I know this presents an unpleasant image, but it is important that your sample for analysis is going to represent what the wildlife out there is actually eating. My understanding is the fish are generally in a frozen state before they are blended and these are not your kitchen blenders anyway, as they typically have titanium blades to prevent laboratory contamination of the sample. Once the fish samples are prepared, they are tested for a number of natural contaminants, including selenium, mercury, cadmium, and arsenic. They are also analyzed for a number of persistent organic contaminates like the pesticides toxaphene, mirex, lindane, endrin, endosulfan, dieldren, DDT, and chlordane. They are also analyzed for other persistent organic contaminants hexachlorobenzene (a fungicide), heptachlorepoxide (a degradation compound of the pesticide heptachlor), and different molecular weight hydrocarbons. Persistent is “environment talk” for organic chemicals that don’t readily degrade and stick around causing endless problems. Fortunately most of these are no longer used in the United States.

Next EPA sorted through a multitude of scientific laboratory studies conducted to establish contaminant concentrations that pose risks to birds, mammals, and fish. There’s currently a huge body of scientific work in this area. EPA wrote the guidelines for conducting ecological risk assessments way back in the 1990s and scientists have been developing data on fatal and sub-lethal contaminant exposure to wildlife ever since. You know that old saying “Whatever kills you makes you stronger?” Well it is definitely not true in the world of toxic contaminants. Sub-lethal in the case of toxic contaminants can have a variety of very nasty consequences for wildlife. Here’s your word for today: teratogen. A teratogen halts or deforms the development of an embryo or fetus. This is a sub-lethal effect.

Environmental scientists don’t use the terms lethal and sub-lethal. They use the terms acute for lethal and chronic for sub-lethal. The concentration of a contaminant known to have a toxicological effect on a wildlife species is called the Toxicity Reference Value or TRV for short. Because nobody wants to have a toxicological effect on wildlife, scientists generally look at only the exposure concentrations that show no observed adverse effects (NOAEL) on wildlife or the low observed adverse effects (LOAEL) on wildlife.

For the national coastal study, EPA looked at a variety of wildlife that all eat fish and developed a generalized NOAEL and LOAEL for the contaminants analyzed. I’m going to use two of the contaminants for comparison: selenium and arsenic. Most people when they think of arsenic, they’re thinking poison, right? Well look at this:

 

Birds

Marine Mammals

Marine Fish

 

Selenium	NOAEL	0.27	0.15	11.04
	LOAEL	0.53	0.24	14.75

 

Arsenic	NOAEL	3.39	0.08	0.06
	LOAEL	8.51	0.4	0.3

 

The numbers you see are in milligrams per kilogram or parts per million (ppm). For a bird the low observed adverse effect of selenium is at 0.53 ppm, while the low observed adverse effect of arsenic is 8.51 ppm. Selenium has a more toxic effect on birds than arsenic does. Marine mammals also have a low TRV for both selenium and arsenic.

But remember now, EPA is examining the condition of the fish and what the toxic impacts are on the birds, mammals and fish that are eating them, not at what level a particular wildlife species starts having toxic effects. They had to calculate what amount of a contaminant in a fish would pose a risk to birds, marine mammals, and marine fish. So they got their fish tissue NOAEL and LOAEL for the toxic impacts by taking the TRV for wildlife species, multiplying it by the general body weight and dividing it by the general amount of fish ingested. Yes they really did this. I know it sounds complicated and frankly the whole process makes my head hurt, but they came up with some figures they could screen fish for and say whether they were in good, fair or poor condition.

Here are the selenium numbers EPA developed for their report:

 

Contaminant	Bird		Marine Mammal		Marine Fish
	Fish Tissue		Fish Tissue		Fish Tissue
	NOAEL	LOAEL	NOAEL	LOAEL	NOAEL	LOAEL
Selenium	0.29	0.57	259.68	428.48	11244.05	15016.72

These figures are again in milligrams per kilogram. Marine mammals like dolphins and seals and marine fish like tuna, shark and swordfish have larger body weights than birds so they can eat fish with a lot more selenium in them before they begin to have toxic effects. Birds also have a greater ingestion rate – they eat more just to keep their body weight up. I guess it takes more calories to fly than to swim around or walk.

So there you have it. EPA established their screening criteria for what constituted fair and poor fish quality based on the consumption of fish by birds.