Organic food starts to prove its worth

At the supermarket, there are usually two sections in the produce aisle. In one, all the fruits and vegetables, from apples to zucchini, are labeled “organic.” Often these products cost more than ones that look the same but don’t have the organic label.
The big price tag can lead people to assume organic food is better than conventionally grown food. But, in the United States, the label simply means that the food has met guidelines set out by the U.S. Department of Agriculture.
For instance, organic fruits, vegetables and other crops must not have been treated with synthetic fertilizers, certain pesticides or sewage sludge. Meat, eggs and milk must come from animals that have been raised according to specific health and welfare standards. Also, farmers may not treat these animals with antibiotics or growth hormones and must raise them on organic feed. Products with multiple ingredients must contain 95 percent or more organic content.
What benefits the organic label might signify, though, has not always been clear.
For years, scientists have been trying to tease out whether organic foods are themselves different than those grown conventionally. Research is beginning to show organic foods can be better — and not only for the people who eat it. Growing foods organically also can help the environment, new data show.

Pesticides are good travelers

On a farm, pests and weeds can destroy a crop. So most U.S. farmers apply chemicals called pesticides to limit the damage.

A farmer in U.S. Midwest uses a crop sprayer to prepare a field for planting. Research finds the chemicals used in conventional agriculture sometimes can end up contaminating areas far from farms.

Aubrey Bunch/USGS

Conventional farmers can apply any pesticide approved for use in the United States. Organic farmers cannot use all of those same chemicals. That doesn’t mean organic farmers allow insect pests and weeds to live peacefully among their crops. They too can use pesticides and weed killers. They just have a smaller list from which to choose.

But none of these chemicals will necessarily stay put. Some share of them will tend to move off through the soil, air or water. Eventually, these pesticides end up in streams where they can mix, creating a mystery soup.
Scientists have been studying how far and how fast pesticides can move through the environment. These data may then point out which animals are at risk of being exposed to the pollutants.
For instance, researchers recently looked at pesticides commonly used on California farms. They found the pesticides in Pacific chorus frogs living in national parks, forests and other locations high in the Sierra Nevada mountains. In some cases, the frogs lived more than 100 kilometers (62 miles) from the nearest farms that had used the chemicals.

A Pacific chorus frog (Pseudacris regilla) in a meadow at Yosemite National Park. Scientists discovered pesticides in the park’s frogs, far from the farms on which the chemicals had been used.

USGS

“This is the first time we've detected many of these compounds, including fungicides, in these remote locations,” says Kelly Smalling. She's the study’s lead author. She's also a hydrologist with the U.S. Geological Survey (USGS) in Lawrenceville, N.J. A hydrologist studies the movement, distribution and quality of water. Her team published its findings in the July 2014 issue of Environmental Toxicology and Chemistry.

Discovering that pesticides contaminate frogs is bad news. Earlier research had found that pesticide exposure could cause problems for the frog’s immune system. And this could alter how the frogs developed. It might even cause male frogs to adopt some female traits.
Smalling and her colleagues think their study supports the idea that pesticides used in conventional agriculture may play some role in the falling numbers of many species of frogs and toads.
But amphibians aren’t the only animals in decline. Honeybees also are in trouble. A problem called colony collapse disorder causes seemingly healthy bees to suddenly abandon their hives. The queen bee remains. Without the worker bees, though, the hive eventually dies.

Honeybees can pick up pesticides as they roam from flower to flower. Some of those chemicals appear able to sicken these important pollinators.

Vicki DeLoach/ Flickr (CC BY-NC-ND 2.0)

A May 2014 study published in the Bulletin of Insectology looked at 18 beehives for almost a year. As they go around collecting pollen, bees may pick up any pesticides that had been sprayed onto the plants they visited.
To probe possible effects of these chemicals, scientists looked at hives whose bees had been exposed to two pesticides: imidacloprid (Ih-MEED-uh-KLOH-prid) and clothianidin (Klo-thee-AN-ih-din). Neither can be used on organic farms. The scientists compared bees in these hives to those in hives free of these chemicals. And they found that even small amounts of the two pesticides triggered a biological change that led to bee deaths.
This suggests the pesticides create unintended problems for growers. Farmers need bees to pollinate many crops, including almonds, cherries and broccoli. If too many bees die, less pollination may occur. And this can shrink farm harvests.
But without using chemicals like these, an influx of pests and diseases also may shrink those harvests. So even organic farms are allowed to use some pesticides. These chemicals just supposed to pose less of a risk to bees and other beneficial wildlife.
Still, those chemicals approved for use on organic farms are not necessarily harmless. One 2010 study in PLOS ONE, for example, looked at organic pesticides applied to soybeans. These chemicals controlled a type of insect known as an aphid. The study found that organic pesticides were more poisonous to the aphid’s natural enemies than conventional pesticides were. That means these organic pesticides may have a worse overall impact on this environment that will conventional ones.

Dirt poor, dirt rich

Pesticides help growers by poisoning some of the farmers’ worst enemies: insects, weeds and disease. But there’s another family of farm chemicals that also help growers: fertilizers. To grow, plants need nutrients, especially the elements nitrogen and phosphorus. And fertilizers add nutrients to the soil.

In this satellite image, coastal water in Lake Erie, near Toledo, Ohio, is colored green by an algal bloom. Such blooms can develop when excess nutrients wash off of farms.

Jeff Schmaltz, Lance/EOSDIS MODIS Rapid Response Team as NASA, GSFC

Organic farmers cannot use these elements if they come from synthetic (human-made) sources, such as ammonia salts. Instead, the farmers need to find natural fertilizers. For instance, they may plant beans. These plants naturally increase nitrogen levels in the soil. Crops that are planted after the beans are gone can now use that nitrogen.

With rich, healthy soil, crops also may need fewer pesticides or fertilizers, farmers are finding. And because they don’t have to use as much of these chemicals, naturally fertilized soils can cut the amount of pollution linked to the frequent overuse of nitrogen and phosphorus.
“Having nitrogen in a plant form, as compared to a liquid form [used] in more conventional agriculture, tends to be less leaky,” notes Meagan Schipanski. As an agronomist at Colorado State University in Fort Collins, she studies soil and crop production. By “leaky,” she means that liquid nitrogen is easily washed out of the soil and carried off the farm. The reason plant-deposited nitrogen tends to stay put is because it “is attached to carbon molecules,” she explains. “There's a molecular bond there” to hold it in place.

Organic farmers often plant cover crops, like these, to promote the growth of beneficial fungi and bacteria in the soil.

Mac Burgess/Courtesy of Meagan Schipanski.

Both nitrogen and phosphorus can build up in nearby waterways. This is called nutrient pollution. Plants and animals need nutrients to thrive. But when large amounts of these elements end up in lakes and oceans, they can cause large growths of algae. Those growths are called algal blooms. They can kill fish and other aquatic life.

The problem can be made worse by unpredictable rains. This may be happening in the Midwest, says Lisa Nowell. As a chemist with the USGS in Davis, Calif., she studies how pesticides and other chemicals affect water quality. In 2012, the Midwest experienced a drought. The following year it rained. A lot. Rivers overflowed their banks. Towns and fields flooded. All that rain risks washing away fertilizers and other chemicals that had collected in the soil, Nowell says.
Indeed, she says: “Preliminary data show really high concentrations of both nutrients and atrazine and other herbicides in the streams. It was kind of phenomenal. And that can cause real problems downstream.” The atrazine (AT-truh-zeen) she mentioned is one of the most common weed killers used in the United States.
Organic farms tend to produce less of that kind of pollution. One reason: These farms often work to build soil that retains more water and that produces less runoff.

This “microarthropod,” here viewed under a microscope, is one of many organisms found in healthy soil.

Rodale Institute

Organic farmers also use compost. This soil-enriching mix is usually made from decomposed plants, food waste and manure. Compost provides nutrients for plants. It also is rich in microscopic life. Research suggests these microbes are important for the health of soils — and plants.

Rick Carr is a compost-production specialist at the Rodale Institute in Kutztown, Pa. He says, “We know that if you have diverse microorganisms in your soil, that's going to lead to better soil health.” Scientists have found evidence that healthy soils help suppress plant diseases. Healthy soils also can help plants take up nutrients and can hold water in the root zone, where plant's most need it.
Carr is researching how microbes in compost can help fight plant diseases. Being full of microbes, “Soil is alive and it's doing things," Carr says. "So we're really relying on the soil. We're taking care of the soil so it can take care of our plants.”

What about us?

Many people buy organic food because they think it's healthier. But whether it is remains an open question — even after years of research and debate. A 2012 study found no real difference between organic and conventional food in terms of nutrition. Its findings appeared in the Annals of Internal Medicine.

There can be big differences in the amount of antioxidants found in conventionally and organically grown nutrient-dense produce, such as tomatoes, a study found.

Chiot’s Run/Flickr (CC-BY-NC 2.0)

More recently, a team of experts in England and elsewhere came to the opposite conclusion. They reviewed all of the research they could find on this question. The team chose 343 studies for its members to analyze. They published their results in the July 2014 British Journal of Nutrition.

Organic crops contain, on average, 17 percent more antioxidants than crops grown conventionally, they found. Antioxidants are compounds in many fruits and vegetables. They are not listed on a product’s Nutrition Facts label. But there is evidence that people who consume foods rich in antioxidants have a lower risk of diseases such as stroke and cancer.
Charles Benbrook is an agricultural economist at Washington State University in Pullman. He also was an author of the British Journal of Nutrition study. And he is quick to point out that his team’s analysis does not mean all organic foods are more nutritious. “Every study reports dozens of results involving different nutrients. For some nutrients, organic might be higher. For other nutrients, conventional might be higher. And for a lot, there are no [real] differences,” Benbrook says

The study did not identify specific  fruits or vegetables where the organic or the conventional variety was more nutritious. However, farming practices can have the biggest impact on nutritionally dense foods, Benbrook notes. “There are only modest differences in the nutrient profile of organic versus conventional cucumbers or lettuce,” he says. But, “there are big differences between conventional and organic berries, apples, tomatoes and other nutrient-dense produce.”

His group’s study also found that conventionally grown farm crops are four times more likely than organic crops to contain pesticide residues. For many people, that's enough reason to buy organic.

Pesticides on foods can be a worry. But a bigger one may be the weed killers sprayed onto lawns.

NadezhdaShour/istockphoto

In 2012, the American Academy of Pediatrics advised parents to reduce their children's exposure to pesticides. Developing fetuses, babies and children are most vulnerable to potential harm, they noted. That’s mainly because their bodies are still developing.

The key concern in the advisory was with direct exposure to pesticides. In places like farms and lawns, people may come into direct contact with these chemicals after they have been sprayed.
What kind of harm might they pose?
Autism is one worry. A2014 study found that when pregnant women lived near fields treated with pesticides, their children were more likely to develop autism. Published in Environmental Health Perspectives, this study surveyed 970 pregnant women. One-third lived less than 1.6 kilometers (1 mile) from a site where pesticides had been applied. Women had a 60-percent higher risk of having a child with an autism spectrum disorder if they had lived closest to sites using insect killing chemicals known as organophosphates (Or-GAN-oh-FOSS-fates). These include diazinon (Dy-AZ-uh-nahn) and chlorpyrifos  (Klor-PY-rih-foss). Neither can be used in organic agriculture.
 Organophosphates work by interfering with the insect brain and nervous system. They may have the same effect on animals, including people, some studies suggest. These chemicals can still be used on many farms.

The American Academy of Pediatrics (AAP) advisory did not make a statement about whether organic food is a better choice for children than is conventionally grown food. The group’s president said that remains an open question.
“Organic foods do have lower levels of pesticides,” said AAP president Thomas McInerny in a statement. Although kids can be more vulnerable to toxic substances, he notes, when it comes to these chemicals “we simply don’t have the scientific evidence to know if the difference will affect a person’s health over a lifetime.”

Diners who want organic benefits but can’t afford to buy only organic foods, might want to consider focusing their purchases on organic foods that will be eaten whole, such as this apple.

SimonQ/ Flickr (CC BY-NC-ND 2.0)

Overall, the AAP emphasized that what’s most important is eating a diet rich in fruits and vegetables — whether they’re organic or not.

What does this all mean when you go the grocery store? There can be benefits for the environment and for the people who grow organic food. There also may be some advantage to people dining on organic foods. For families who can afford them, organic foods might be worth the higher price. Where money is tight, people can buy targeted organic foods. They might choose an organic apple, for instance, since the skin of that fruit will get eaten. But you can buy the conventionally grown avocado since its skin — and any pesticides on it — will be discarded.
But no one should be deterred from buying fruits or vegetables. An apple is always going to be a healthier snack choice than a bag of chips — no matter how the piece of fruit was grown.