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Antibiotics in Fish

Story at-a-glance -

  • In the last two decades, aquaculture production has nearly tripled, and with the rise has come a significant increase in the use of antibiotics.
  • Researchers detected five different antibiotics in shrimp, salmon, tilapia, and trout (including one brand labeled antibiotic-free)
  • Some of the antibiotics detected also showed up in wild-caught seafood, likely due to wastewater treatment plant runoff
  • Pesticides used to treat sea lice on fish farms are being detected in the environment at levels that threaten shellfish and other marine wildlife

Understand That There Are Antibiotics in Your Fish

November 05, 2014 | 50,502 views

By Dr. Mercola

Animals raised in confined animal feeding operations (CAFOs), such as cattle and chickens, are often fed antibiotics at low doses for growth promotion, and those antibiotics are transferred to you via meat, and even via the manure used as crop fertilizer.

The same problems that are occurring on land are now, tragically, also occurring in the sea, with farmed fish becoming another major outlet for antibiotic usage.

Unlike in land animals, fish are not fed the antibiotics for growth promotion but rather for disease prevention. Industrial fish farming, or aquaculture, is the fastest growing form of food production in the world.1 About half of the world's seafood now comes from fish farms, including in the US, and this is expected to increase.

The close quarters where farmed fish are raised (combined with their unnatural diets) means disease occurs often and can spread quickly. On fish farms, which are basically "CAFOs of the sea," antibiotics are dispersed into the water, and sometimes injected directly into the fish.

Unfortunately, farmed fish are often raised in pens in the ocean, which means not only that pathogens can spread like wildfire and contaminate any wild fish swimming past – but the antibiotics can also spread to wild fish (via aquaculture and wastewater runoff) – and that's exactly what recent research revealed.

Multiple Antibiotics Detected in Shrimp, Salmon, Tilapia, and Trout

In the last two decades, aquaculture production has nearly tripled, and with the rise has come a significant increase in the use of antibiotics. In the largest study of antibiotics in US seafood to date, researchers detected five different antibiotics in shrimp, salmon, tilapia, and trout.2

Some of the antibiotics detected are also used to treat human diseases and showed up in wild-caught seafood as well, likely due to wastewater treatment plant runoff.3 Further, even a variety of farm-raised salmon that was labeled as antibiotic-free was found to contain antibiotic residues.

Even though the levels detected were low, and within legal limits, the threat of antibiotic resistance still remains. In fact, the researchers noted that publications reporting antibiotic resistance in aquaculture have increased 8-fold over three decades.4

"Antibiotics present at levels well below regulatory limits still can promote the emergence of drug resistant microorganisms," they noted.5

Pesticides Used on Fish Farms Threaten Wild Shellfish

Sea lice, a type of crustacean that is easily incubated by captive fish on farms, have become a significant problem and have been blamed for declining numbers of wild pink salmon, as well as the species that eat them (bears, eagles, orcas, and others).

To control the sea lice, fish farms use numerous pesticides, including diflubenzuron, teflubenzuron, emamectin benzoate, cypermethrin, and delta-methrin. These chemicals are now showing up in dangerous levels in the water, seabed sediment and various marine organisms near Norwegian fish farms.

According to a study by the Norwegian Institute for Water Research, levels of the pesticide teflubenzuron in sediment exceeded environmental quality standards (EQS) in 67 percent of the samples, while levels of the pesticide diflubenzuron exceeded EQS in 40 percent of the samples tested.6

The levels were so high that shellfish and other marine wildlife in the area may be threatened. The researchers said:7

"A crude assessment of the concentrations [of pesticides] detected in the shrimp collected from one location and the levels at which chronic effects are seen in shrimp would suggest that there is a potential risk to shrimp. It would also be reasonable to extrapolate this to any species that undergoes moulting during its life cycle."

The extensive use of these chemicals in aquaculture could easily have devastating ramifications, especially considering how far they travel in the water and how long they persist. One study found a drug used to kill sea lice also kills other marine invertebrates, can travel up to half a mile and persists in the water for hours…8

And, as we often see when chemicals are freely dispersed into the environment… nature often finds a way around them. Sea lice are now becoming resistant to the commonly used pesticides, representing a serious challenge. As reported by the Institute of Marine Research in Norway:9

"Pesticide resistance represents a global challenge to food production. Specifically for the Atlantic salmon aquaculture industry, salmon lice and their developing resistance to delousing chemicals, for example emamectin benzoate, represents a challenge to sustainability."

Antibiotics May Contribute to the Spread of Salmonella

Agricultural uses of antibiotics account for about 80 percent of all antibiotic use in the US.10 It's beneficial for farmers because continuous, low-dose administration can increase the rate of weight gain in livestock for a relatively low cost to the farmer.

Unfortunately, this practice is also contributing to the alarming spread of antibiotic-resistant disease – and may also be promoting the spread of Salmonella bacteria among infected animals, according to new research.

It's known that certain animals may act as "superspreaders" of disease, in which they shed large amounts of bacteria in their feces that may make other animals sick, yet the superspreaders have no symptoms themselves.

The animal study showed that some Salmonella-infected mice given the antibiotic streptomycin began to shed large quantities of the bacteria in their feces, essentially becoming superspreaders (except in this case the animals also became ill).11

In other words, instead of reducing the risk of infection, the antibiotic treatment had the opposite effect and instead increased infection risk. And the results held true with another antibiotic, neomycin. The study's lead researcher noted:12

"If this holds true for livestock as well, and I think it will, it would have obvious public health implications. We need to think about the possibility that we're not only selecting for antibiotic-resistant microbes, but also impairing the health of our livestock and increasing the spread of contagious pathogens among them and us."

Pork Industry Uses Web Marketing to Sugarcoat Agricultural Antibiotics Use

Last month, PBS Frontline ran a program titled "The Trouble with Antibiotics," which detailed the growing crisis of antibiotic resistance in the US. According to a 2013 report by the US Centers for Disease Control and Prevention (CDC) on antibiotic-resistant threats,13 antibiotics in the American food supply pose "a serious threat" to public health and "should be phased out."

The World Health Organization (WHO) has also warned that we are headed for a "post-antibiotic era" where we will see common infections turning deadly. After years of prodding, the US Food and Drug Administration (FDA) finally issued updated guidance on agricultural antibiotics on December 11, 2013.

However, all they really did was ask drug companies to voluntarily restrict the use of antibiotics that are important in human medicine by excluding "growth promotion in animals" as a listed use on the drug label.

The President's Council of Advisors on Science and Technology has also stepped in, recently announcing a five-year plan to address antibiotic resistance. Unfortunately, a five-year plan is simply too little, too late. We don't have that kind of time to waste. For each year we delay action, tens of thousands of Americans die, and the resistance problem keeps growing unfettered.

According to CDC statistics, 2 million Americans are infected with antibiotic-resistant bacteria each year, and at least 23,000 of them die as a result of those infections.14 Meanwhile, you have a 50/50 chance of buying meat tainted with drug-resistant bacteria when shopping at your local grocery store.15

The issue is becoming widely known, and the National Pork Board anticipated a flurry of Web activity related to Frontline's antibiotics program, which directly asked whether "decades of antibiotics in our farm animals" might be related to the rise of antibiotic-resistant bacteria.16 And so, they took matters into their own hands, using paid search engine optimization to ensure that their pro-antibiotics industry Web site had a prominent spot in Web search results. Jarrod Sutton, vice president for social responsibility at the National Pork Board, said in the email seen by Reuters:17

"The industry will tie any consumer searches for 'PBS Frontline' and 'Antibiotics' to the U.S. Farmers and Ranchers Alliance site, Food Source … Included in these searches will be the terms 'pork, antibiotics and Frontline.' In those cases, users will be directed to the National Pork Board and [National Pork Producers Council] NPPC site PorkCares.org."

It's not the first time the pork industry has used PR campaigns to sugarcoat the realities of CAFO operations. In 2012, the Pork Producers Council released a video that made CAFOs look like idyllic family farms, when in reality these factories are among the most cruel, most polluting and most disease-ridden facilities on the planet.

Are You Interested in Clean Eating?

So-called "clean eating" is seeking out whole foods that are free of toxic chemicals and additives, including those widely used in industrial farming on both land and sea. Despite evidence showing that agricultural antibiotics are a driving factor in environmental pollution and the spread of antibiotic-resistant disease, very little is actually being done to curtail the situation. The agricultural industry and the aquaculture industry are also dragging their feet, despite mounting evidence that they are promoting a massive health-care and environmental crisis. My suggestion to you is: don't wait for CAFOs and fish farms to voluntarily do the right thing.

Don't wait for the government to implement an action agenda. Instead, take decisive action for yourself and your own family. Seek out trusted sources of food that do not use antibiotics and pesticides. Many small farmers use organic principles even if they have not been able to afford organic certification, so your local farmer or farmer's market is a good place to start. Some grocery chains also offer 100% grass-fed meats; if not, ask them to start carrying it. As for seafood, avoid fish and shellfish raised in aquaculture environments and choose only seafood that is wild-caught, in non-polluted waters, and is certified by the Marine Stewardship Council (MSC), which means it came from fisheries that support sustainable fishing practices.

From a health and environmental perspective, the best choices for seafood include wild-caught sardines, anchovies, and Alaskan salmon.

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