The University of Minnesota study will add to the level of public concern about the food the eat. It also serves as a warning to food processors that they need to be vigilant when sourcing their vegetables.
The processing industry is under regulatory and consumer pressure to ensure the safety of their food products. Regular breakdowns in food safety and reports on contamination have raised consumer awareness about the problem.
The study, published in the Journal of Environmental Quality, indicates that processors will have to be careful when sourcing their vegetables, whether non-organic or organic. The contaminationthreat is due to the US laws allowing farmers to use animal manure as fertilizer in both conventional and organic agriculture.
In the study, University of Minnesota researchers found that corn, cabbage, and green onions absorbed chlortetracycline from manure fertilizer obtained from pigs that were given the antibiotic.
Chlortetracycline is a member of the tetracycline class of antibiotics that are used in human medicine to treat upper respiratory tract infections and other illnesses. Tetracyclines and otherantibiotics also are used as feed additives in poultry, hogs and beef cattle.
Feed additives are not used to treat disease, but to promote slightly faster growth and to compensate for overcrowded and unsanitary conditions on industrial-scale farms.
When the antibiotics are ingested by a human they can spur the bacteria naturally present in the intestinal tract, including types of bacteria that can cause serious disease, to becomedrug-resistant, the researchers stated.
"Vegetarians may think the huge overuse of antibiotics in livestock and poultry will not affect them, but that's not true for two reasons," stated Margaret Mellon, the director ofthe Union of Concerned Scientists' Food and Environment Program. "Consumers eating vegetables grown on soil fertilized with manure may be unknowingly ingesting antibiotics. Even moreimportantly, resistant bacteria that are created on the farm can contaminate air, water and soil that can travel significant distances."
While raw and composted manure may be used with little restriction in conventional agriculture, the US Department of Agriculture's rules requires that manure used in organic farming be composted orbe applied at least 90 days before harvest. In the study, the crops were harvested within only 42 days, so the findings may not apply to organic vegetables, the researchers stated.
Demand for organic foods has increased by almost 17 per cent over the past year, according to a report this week by Whole Foods Market. The latest survey commissioned by leading organic supermarketreveals that about two-thirds of the US' consumers bought organic goods in 2005, compared to just over half in both 2003 and 2004.
According to the Organic Trade Association's 2004 manufacturers' survey, the organic foods industry had $10.8 billion in revenues in 2003 and has grown at an average rate of 19.5 per cent per yearsince 1997.
Market researcher Euromonitor predicts that sales of packaged organic foods alone will be worth $8.6 billion at retail by 2009 - up from 5.1 billion in 2003.
Most of the participants said they opt for organic goods in order to avoid pesticides, for their freshness, for their nutritional benefits and in an effort to avoid genetically modified foods.
A majority of consumers also felt organic products were of better quality, as well as being better for the health and the environment.