Heather Kindberg, Contributing writer

Organic food has risen to become a major market over the past quarter century.

According to industry-standard surveys completed by the Organic Trade Association, 2008 organic food sales in the U.S. totaled nearly $23 billion. Although this accounts for only 3.5 percent of all U.S. food sales, it was a 15.8 percent increase from 2007, while the entire U.S. food sales averaged only a 4.9 percent increase.

Supporters say there are two major benefits to eating organic food. First, it's a socially and environmentally-conscious choice: Organic food supports sustainable agriculture rather than destroying the land and contaminating the environment, and it often better supports smaller local growers. Second, it's healthier to eat products that do not have toxins in them than to eat those that do.

In the scientific community, synthetic pesticides, herbicides and hormones are highly suspected of or have proven to be contributors to many illnesses. Researchers at the Harvard School of Public Health found that "individuals reporting exposure to pesticides had a 70 percent higher incidence of Parkinson's disease than those not reporting exposure." Another study printed in the Archives of Neurology in July 2009 found "elevated levels of organochlorine pesticides in postmortem Parkinson's disease brains."

Organochlorines have been attributed to causing cancer, birth defects and nervous system damage, among other health issues. They contain known toxins such as chlorine and carbon, and these pesticides accumulate in plants, animals and in the ground. This accumulation becomes more concentrated as it progresses up the food chain. Many organochlorines have been banned for use in the U.S. and around the world, while others are still commonly used in agriculture today.

Organic food is often more expensive to purchase than food grown by the 20th century's so-called conventional means. It is much more time-, cost- and labor-intensive for farmers to deal with weed and pest control without synthetic herbicides and pesticides. Organic farmers also do not over-farm their land, so they must rotate their crops and allow time for land to lie fallow. Organic feed for livestock is more expensive than conventional feed, and without using synthetic growth hormones and steroids, organic livestock does not have the benefit of accelerated growth.

Yet, even with the higher cost of organic food, there are certain foods that present the biggest health benefits and are well worth the extra money.

Beth Ardapple is a longtime organic farmer and organic agriculture activist who serves as the development director on the Arkansas Public Policy Panel. Ardapple named some organic foods with the greatest benefit.

Baby Food -- Switching to organic baby food is a critical change because infants are so susceptible to toxins, she says. In a study done by the Environmental Working Group, 16 different pesticides were found, in various quantities, in baby food made by the three major baby food producers.

Kids' favorites -- In their developmental years, children are at high risk when toxins are introduced to their systems. Kids also tend to eat fewer varieties of food, so they are subjected to the same pesticides more frequently. Her tip is to replace the foods that kids eat with the most regularity with organics.

Fresh Fruit -- Conventional fruit can remain contaminated by pesticides even after washing and peeling, and even in those with skins as thick as bananas and cantaloupe. Vegetables are also a big concern, but fruits were found to hold more contamination as a group.

You can buy in-season produce to find lower prices.

Products Containing Animal Fats

Since chemicals ingested by animals become concentrated in their fat tissues, switching to organic butter, milk and cheese will eliminate a major source of genetically engineered hormones, along with herbicide and pesticide contamination.

The labeling requirements of the National Organic Program under the USDA are specific. Purchasing foods labeled "100 percent organic" is the ideal. For complete distinctions of labeling terms, read the National Organic Program Organic Labeling and Marketing Information pages.