Acetaminophen: Soaked Up By Our Finned Friends

Reference: Choi E, Alsop A, & Wilson JY. (2018). The effects of chronic acetaminophen exposure on the kidney, gill and liver in rainbow trout (Oncorhynchus mykiss). Aquatic Toxicology, 198, 20-29. https://doi.org/10.1016/j.aquatox.2018.02.007

Got a headache? Fever? Back pain? You can’t be slowed down! You have too many things on your “To Do List”!

At this point, you grab the bottle of Tylenol (a.k.a acetaminophen) and take a couple pills to alleviate the pain. Within an hour, you are feeling better and continue on with your day. We could end the story there, but what happens next?

Not all of the acetaminophen that you take is used in the process of providing you pain relief. A portion is excreted with your urine and ultimately released into the nearest body of water (i.e. lake, river) where it can have an effect on our finned friends. Because acetaminophen is one of the most commonly used pain killers today, considerable quantities can be frequently detected in surface waters and wastewater effluent discharged into the environment.

What does acetaminophen do to fish???

Choi and colleagues took on the challenge of understanding the effects of acetaminophen on the structure and function of three very important fish organs: liver, kidney and gills.

A brief review:

• The liver breaks down nutrients such as fats and carbohydrates into forms that can be easily used by the body for energy. In addition, the liver breaks down toxicants into less harmful pieces that can be quickly excreted.
• The kidney helps ensure a delicate balance is maintained between the amount of minerals and energy molecules retained by and released from the body. Too little or too much of either could be problematic.
• The gills are responsible for the uptake of oxygen and help fish to excrete toxins or take in minerals to maintain appropriate levels.

How do you determine if acetaminophen has an effect on fish?

Choi and his team evaluated the effects of acetaminophen on fish by conducting two separate experiments to determine if the structure and function of rainbow trout liver, kidneys and gills were altered due to duration and/or magnitude of exposure.

The first experiment had two groups of rainbow trout immersed in different concentrations of acetaminophen in water (0 and 10 ug/L) for up to a 6-week period. Every two weeks fish were taken from each group, euthanized, and organs were dissected out for examination. This allowed them to observe changes in organ structure from each group at three different time points.

The second experiment had three groups of rainbow trout each immersed in a different concentration of acetaminophen in water (0, 10 or 30 ug/L). After 4 weeks, the fish from each group underwent different tests to measure:

• Swim performance
• Efficiency of oxygen uptake
• Activities of enzymes that assist in moving minerals in and out of the body
• Amount of urine excreted
• Quantities of minerals, proteins, sugars and toxins in tissues, blood and urine

These tests provided the needed information to determine if function of the liver, kidney and gills were hindered after exposure.

Did it have any effect on the trout??

Short answer: Yes.

Slightly longer answer:

Rainbow trout exposed to acetaminophen showed signs of altered cellular structure in their liver, kidney and gills within 2 weeks. The severity of these alterations in the kidney and gills increased with exposure time.

The effects on organ function:

• Several minerals, sugars and proteins were found in the urine of fish exposed to acetaminophen. This indicated the kidneys suffered damage, which hindered their ability to resorb these nutrients back into the body.
• Acetaminophen reduced the fish’s ability to reach and sustain higher swim speeds. Essentially, these fish were slower and fatigued more quickly. Choi suggested the structural changes in the gill tissue decreased the trout’s ability to absorb oxygen efficiently from the water thus effecting their swim performance.
• Rainbow trout exposed to acetaminophen also showed reduced energy stores in the liver suggesting that there was a metabolic cost associated with this exposure.

Despite all these problems, not a single mortality occurred among the fish due to acetaminophen exposure.

If the trout didn’t die then there is no real problem, right?

Perhaps. The rainbow trout in this study demonstrated that they can compensate for tissue damage associated with acetaminophen exposure and still stay alive in a laboratory. It is a big bad world out there with more than a single chemical to stress them out. They have to deal with water quality fluctuations, temperature changes, acquiring food, avoiding predators, seducing a mate, producing offspring and migrating. Acetaminophen exposure may put them at a disadvantage by reducing their capacity to swim fast and maintain nutrient levels they require to successfully complete these activities.  Consequently, this could impede their growth, reproduction and their survival in the wild.

What can you do to help?

Safe disposal of unused or expired prescription drugs, over-the counter medications and natural health products is a great step towards reducing the environmental impact of these chemicals. Please bring them to your local pharmacist for proper disposal; please don’t flush them down the toilet or sink!

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