Every year the Environmental Working Group puts out a list of the cleanest and dirtiest produce items to help shoppers make healthier decisions at the grocery store. I love this list! It is a great list to keep handy on your phone as a guide when you are in the grocery store. If you are trying to add organic foods to your diet but feel overwhelmed, this is a great way to start.
The Dirty 12 are the items which contain the highest levels of pesticides and contaminants. These should be bought organic and washed thoroughly.
The Clean 15 are the items which contain the lowest levels of pesticides and contaminants. These can be bought conventional if organic is not available.
The ewg.org website is a wealth of information, check it out for more info on the clean 15 & dirty 12 as well as contaminant info on almost any products you use from household cleaners to makeup. They have a great app as well to use on the go.