Ryan Van Velzer

The Republic | azcentral.com

Trace amounts of antibiotics have shown up in seafood that would have landed on grocery-store shelves in Arizona and California, according to an Arizona State University study published in Journal of Hazardous Materials.

Wild shrimp and farmed tilapia, trout, salmon and even farmed salmon marketed as antibiotic-free tested for detectable levels of antibiotics, said Hansa Done, the report's lead author and a graduate student at ASU's Biodesign Institute.

The levels of antibiotic residues found in the fish are well within the Food and Drug Administration's regulations for safe consumption, some 100 to 1,000 times lower than the limit, Done said.

But just because it's safe to eat, doesn't make it sustainable, she said.

These farms often rely on antibiotics to combat diseases created in aquaculture environments, according to the report.

Done is concerned that the use of antibiotics in fish farms will increase the likelihood of antibiotic-resistant bacteria that could end up in food and make people sick, she said.

"This is part of a larger issue with animals that are farmed for human consumption. This is more known with swine, poultry and cattle," Done said.

"If you are feeding them the same antibiotics used to treat the same diseases that humans get, well then, these antibiotics won't work anymore."

The report states that a review of scientific literature found that even trace amounts of antibiotics can promote resistance in micro-organisms.

The FDA agrees the use of any antibiotic can contribute to bacterial resistance in humans, animals or plants, said Lauren Sucher, an FDA spokeswoman.

"The FDA believes it's important to use medically important antibiotics judiciously so we can preserve their effectiveness when needed to treat human disease," she said.

In the study, Done and fellow researchers tested for the presence of 47 antibiotics in some of the most commonly consumed seafood including shrimp, salmon, tilapia, trout and catfish.

After testing 27 samples donated from the National Oceanic and Atmospheric Administration — the government agency responsible for seafood imported in to the U.S. — Done found traces of human and veterinary antibiotics that treat infections such as chlamydia, psittacosis, pneumonia and dermatitis.

Researchers detected five antibiotics:

- Oxytetracycline - in wild shrimp, farmed tilapia, farmed salmon and farmed tout with spinal deformities.

- Epioxytetracycline - in farmed salmon.

- Sulfadimethoxine - in farmed shrimp.

- Ormetoprim - in farmed salmon.

- Virginiamycin – in farmed salmon marketed as antibiotic free.

The seafood used in the testing came from 11 countries, Done said.

In fact, The U.S. imports more than than 90 percent of its seafood supply and about half of that comes from fish farms, according to the U.S. Food and Drug Administration.

Although all seafood imports go through the NOAA, the FDA has a targeted inspection program, called import alerts, that allows it to detain goods that don't meet FDA standards.

In 2013, the FDA began a plan to phase out the use of what they deem "medically important antimicrobials" in animals for food production, Sucher said. Working with veterinarians and drug manufacturers, the FDA hopes to provide more veterinary oversight while limiting the use of antibiotics that could be used to treat human infections, she said.

The ASU report notes that although the sample size was limited, it represents the largest study of its kind on U.S. seafood and proves that low levels of antibiotics residues exist in seafood for human consumption.