Antibiotic use in crop production is more widespread than expected

The overuse of antibiotics and the risk of bacterial resistance is widely documented. But now, new research is calling attention to a lesser known role of antibiotics in crop production. According to the study, antibiotics are being used much more frequently and for a greater variety of crops than previously realized. 

Antibiotics have been used for decades to control plant diseases on crops like apples and pears. The drugs have been effective in controlling some bacterial diseases, but not much is known about the extent of their use worldwide.

The investigation, which included experts at the World Health Organization and the Food and Agriculture Organization, revealed that few countries are currently monitoring the use of antibiotics in crop production. Out of 158 countries, only three percent had any kind of regular assessment of the types and amounts of antibiotic use on crops.   

The lack of data on the use of antibiotics in agriculture makes it seem that the amounts being used are insignificant. 

After analyzing more than 436,000 records from Plantwise plant clinics in 32 countries, the experts discovered that antibiotics are being recommended for use on over 100 crops and often in large quantities.

The researchers estimate that 63 tons of streptomycin and 7 tons of tetracycline – drugs that are considered critically important for human medicine – are annually sprayed on the rice crop in Southeast Asia alone. 

According to the study, antibiotics are being predominantly used against bacterial diseases. However, the team also found an alarming level of recommendations for antibiotics against crop issues that are not known to be effectively treated by these drugs. 

“There is a considerable proportion of crop advisors recommending antibiotics against insect pests, either the advisors are unaware that they will have no impact on insect pests or they are recommending antibiotics as a preventative measure against bacterial diseases,” said study lead author Dr. Philip Taylor.

The researchers found that 11 different antibiotics are being recommended for use on crops grown in the Americas, Eastern Mediterranean, Southeast Asia, and the Pacific rim countries. 

The quantities used for crop production are small compared to medical and veterinary use, but there is still concern about bacterial resistance.

Previous studies have shown that when antibiotics are mixed with other agro chemicals, bacteria can develop resistance to the antibiotic up to 100,000 times faster. The consumption of raw food may also provide an avenue for the development of resistant bacteria.

“Further research into the scale of antibiotic use in crop protection is warranted as the potential for interactions with other crop protection products that might promote cross-resistance or co-selection for antibiotic resistance is considerable,” said study co-author Dr. Rob Reeder.

“There is considerable attention paid to the medical and veterinary use of antibiotics, but there is a paucity of data on their use in global crop production. The only well documented use of antibiotics on crops is that on top fruit in the USA. These data appear to indicate that the use of antibiotics in crop production is more extensive than most of the literature would suggest.”

Dr. Taylor noted that there is evidence to suggest that crops are a potential vehicle for resistant bacteria to enter the human gut, and this is an area where further research is needed.

On the other hand, people who are in support of antibiotic use in crop production argue that there is no proven evidence of resistance having spread from plant pathogenic bacteria to human or animal pathogens.

“It is hoped that the data presented in this paper will increase the debate regarding the use of antibiotics against crop pathogens and that crop production will be included under the one health umbrella.”

The study is published in the journal CABI Agriculture and Bioscience.

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By Chrissy Sexton, Earth.com Staff Writer