Monitoring Pesticides in Our Food

Next time you walk up and down the aisles of your favorite supermarket, think about this—on average 35 percent to 40 percent of all food and fiber crops grown around the world are lost to pests and disease every year. As food safety and risk management professionals, we can all readily appreciate the importance of pesticides in preventing potential food shortages or worse. In fact, pest control dates back to the first person to swat a bug. More methodical methods soon followed. The Sumerians used a sulfur compound to drive off insects. The Egyptians had over 800 recipes for pesticides, while the Chinese used arsenic and mercury compounds to control plant diseases and fend off pests.

The Ubiquity of Pesticides

Though often misunderstood to refer only to insecticides, the term pesticide also applies to herbicides, fungicides, and various other substances used to control pests. Today, more than 5.5 billion pounds of these chemicals are applied to seasonal crops around the world each year. The U.S. agricultural industry alone uses over half a billion pounds of pesticides a year to treat just 21 selected crops, including corn, soybeans, and wheat. According to USDA, about 76 percent of those pesticides are herbicides, 17 percent are soil fumigants, desiccants, and plant growth regulators, while insecticides account for the remaining 7 percent.

With all of those chemicals ending up on global crops, it should come as no surprise to learn that trace amounts of those chemicals end up in the food supply. Remember your mom always telling you to wash that fruit or vegetable before eating it? Turns out she was right. Residual pesticides are found in 52 percent of fruits and over 30 percent of vegetables. But even mom’s advice does not often help, since washing foods does not always remove all of the chemicals. Beyond those that cling to the skin of fruits, vegetables, and grains, some are actually absorbed into the food itself. Despite all of the preventive measures in place, consumers are still eating pesticides on a daily basis.

Even more disturbing is the potential accumulative effects of longtime exposure to these chemicals. The possible implications of exposure to multiple pesticides on food are also of growing concern. It is not uncommon, for instance, to treat crops several times with different pesticides depending upon treatment needs, including insects, rodents, fungi, and soil enhancers. One recent study linked multiple myeloma to certain agricultural exposures, including pesticides, in men throughout North America. Another recent ruling in California will soon require a cancer warning to appear on glyphosate, the world’s most popular weed killing pesticide.

Preventive Measures Abound

In most countries pesticides are highly regulated and designed to dissipate by harvest time, leaving behind only trace amounts of compounds that are measured in the parts per million and billion (ppm and ppb) levels. Government regulators note that those levels are below the legal tolerance limits set by food safety agencies from around the developed world, and are thus safe for human consumption. In every instance, these tolerance levels already factor in an added safety margin that considers their potential impact on children, who consume more food by body weight, as well as people with higher sensitivities.

In order to verify these tolerance standards, farmers, food manufacturers, processors, packagers, and some larger grocery chains now conduct their own testing to make sure every ingredient is within the established tolerance limit. In states like California, which has the strictest standards for pesticide use, testers are mandated by law to fully describe or reference the preparation process and methodologies used as well as provide validation data and all analytical reports upon request.

Testing Methodologies

What do most testing laboratories use to detect, identify, and quantify pesticides in food? While there are multiple methods to measure pesticides at environmentally relevant concentrations, the industry gold standard is chromatography. Both gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) meet the analytical requirements to detect pesticides in food, especially in fruits and vegetables.