The real answer to this question is multifaceted. I could (and might) write an entire book trying to answer this question. I'm going to use an analogy like smoking to communicate why organic food is less harmful than non-organic food and why you should try to eat organic food.
Most people who smoke cigarettes smoke multiple cigarettes per day. It takes more than one cigarette to cause a heart attack or cardiac disease combined with a variety of lifestyle factors that come into play. The damage to the body, from smoking, occurs over a person's lifetime. Theoretically, the same occurs with chemical exposure from food and the environment.
What does smoking have to do with organic food?
Eating non-organic fruits, vegetables and other foods can be similar to smoking. Non-organic food, such as fruits and vegetables, are sprayed with a variety of pesticides (bug killers), herbicides (weed killer) and fungicides (fungus killer) to protect them from bugs, weeds and fungus. By eating non-organic dairy, meat, eggs and poultry, again, you may be exposing yourself to: chemicals that the animals/livestock may have consumed in their feed (hay and grains), residual hormone administered to the animal/livestock and/or medication that has been administered to the animal. By eating non-organic foods, you potentially expose yourself to these chemicals each time you eat or have a snack. Just like smoking, you are unnecessarily exposing your body to a variety of chemicals that may have effects on endocrine (hormones), genetic (DNA) and epigenetics (environmental factors that affect DNA). A couple good books on environmental toxins and their effects on people and animals is Our Stolen Future by Dianne Dumanoski, John Peterson Myers and Theo Colborn and Silent Spring, by Rachel Carson.
How much chemical am I consuming?
That's a great question and an equally difficult one to answer. The short answer is: it depends on how much non-organic food you consume and where it is grown. You are exposed to a variety of chemicals through air, food, water, toiletries, bedding etc; however, you can minimize the quantity of chemicals that reaches your gastrointestinal tract. The USDA uses a system of pesticide regulation called Maximum Residue Limits (MRL). The following information is from the USDA website:
More than 300 fruit, vegetable and nut commodities, as well as more than 270 pesticides approved for use on those commodities by the U.S. Environmental Protection Agency
More than 425 pesticide and veterinary drug residue tolerances in major export markets for hay, feed, grains, oilseeds, poultry, eggs, meat and dairy
But organic food is so d@3* expensive.
Yes. I know. It's really unfortunate that to eat healthier, you often have to spend more money. I look at it like this. Organic food is expensive but a disease process combined with pharmaceutical drugs is expensive (especially without insurance) too. When you compare the financial costs of organic food with the financial, physical, emotional, mental, social, time and spiritual costs of developing a preventable illness there is no comparison of cost. An investment in fresh, organic food is an investment in you on this earth. Eating organic will not help you live forever, but can certainly decrease your exposure to unnecessary chemicals; and with other healthy lifestyle choices, can help to prevent disease. Now, a great alternative to spending that money would be to grow your own garden and harvest your own crops. It's a fair amount of work depending on the size of the garden, but worth it come harvest time.
Bottom Line: You, it's all you really have.
I know. It's not all about you. It's really about other people, but being the best that you can be. Improving your fitness at all levels will help to ensure that you will be a better father, mother, brother, sister, aunt, uncle, grandmother, grandfather, friend, husband, wife, trucker, writer, athlete, engineer etc. Bettering your health is both directly and indirectly bettering the health of those around you.