The Greek physician Hippocrates told his patients: "Let food be thy medicine and medicine be thy food."

 What is organic food? - "An apple a day keeps the doctor away" - have echoed the notion that fruits and vegetables are the very wellspring of our health. And they are. They're loaded with minerals, nutrients and phyto-nutrients that super-charge our immune systems. They promote good digestion and, among lots of other benefits, they support better brain function and memory. But, today, when we're at the grocery store and we pick up a shiny crimson apple produced by some distant unknown farm, many of us think: Is this good for my kids? Here you will find some videos with baby food recipes.

In recent decades, as the use of chemical pesticides and herbicides has increased in conventional farming, scientists and activists have raised concerns that chemically treated fruits and veggies could be causing serious health problems in our kids. A Harvard School of Public Health study found a higher risk of attention deficit disorder among kids exposed to pesticides, for instance. CNN reported a link between pesticides and autism.

USA Today reported that pesticides "are known to be toxic to the nervous system, cause cancer, disrupt hormones and cause brain damage in children."

Most of us can't afford to feed our kids 100 percent organic diets-or anything close to that. So we wonder: How toxic is chemically treated produce, really? And when it comes to buying organic, what's worth the splurge and what's not?  The D.C.-based organization Environmental Working Group has been tracking and publicizing research about pesticides in produce for decades. Every year they boil down their research into a user-friendly shopping guide known as the "The Dirty Dozen" and "The Clean 15" - lists that show which fruits and veggies have the highest concentration of pesticides, and which have the lowest. To compile this list they sift through Department of Agriculture data and analyze the chemical residues still present in and on produce items after they've been washed and peeled. 

Related: 7 superfoods to eat for healthy, glowing skin

 Of the fourteen fruits and vegetables on their 2013 Dirty Dozen Plus list, five are veggies we commonly feed our kids. They are, in order of contamination levels:

1. Apples
2. Celery
3. Cherry tomatoes
4. Cucumbers
5. Grapes 

EWG's findings have been called into question by critics who say that the pesticide levels on conventional produce are trace, and very rarely exceed government limits. They contend that the worst health impacts of pesticides can only come from extreme, sustained exposure. 

There are problems with this logic. For one thing, kids eat much more fruits and vegetables relative to their physical weight then we do, and their growing bodies and evolving brains are more sensitive to the health impacts of pesticides than those of adults.

EWG's concern, moreover, is not just the amount of pesticide residue on these fruits and veggies, but the variety. On celery, for instance, USDA data shows the use of more than 60 different pesticides.

We - and, for that matter, the government - know scarily little about many of the chemicals that are in commercial use. Just last year, the EPA banned a pesticide known as "AZM" or "guthion" which had been widely used on apples, and also applied to cherries, pears and blueberries. More than 50 years after this chemical had been registered, government officials determined that it was a neurotoxin. Why government officials allow such chemicals to be used before they've more fully researched their potential impacts we will never understand. There is, we're happy to report, some good news. For one thing, not all conventional produce is doused equally. While the Dirty Dozen have the highest concentration of chemicals, there are plenty of other fruits and vegetables like avocado and sweet potatoes that have barely detectable levels. The EWG's Clean 15 include the following, which are also among our kids' faves: 

1. Asparagus
2. Avocado
3. Cantaloupe
4. Sweet corn
5. Mango
6. Mushrooms
7. Onions
8. Pineapple
9. Sweet peas, frozen 
10. Sweet potato 

There's more good news: It's never too late to make the switch to organic. A 2008 Emory University study found that when children shifted from conventionally grown to organically grown fruits and vegetables, the traces of the most concerning pesticides in their urine fell to zero. 

There's no safer, more delicious or more affordable way to eat fruits and vegetables than from your own backyard or rooftop farm. (If you haven't already, check out our Rookie Guide to DIY Farming, a crash course in growing your own organic groceries.) But even those of us with gardens still supplement with store-bought produce.

 When your budget allows for organic purchases, don't waste it on the Clean 15, just hit the Dirty Dozen