Decomposition Rates
paper 2.5 months
orange peel 1-6 months
cigarette butt 5-6 years; chemicals also leach into water and poison wildlife
milk carton (cardboard) 5 years
plastic bag 10-20 years
plastic cup lids, utensils 20-30 years
metal bottle cap 50 years
foamed plastic cups, plates 50 years
disposable diaper 75 years
plastic bottle 100-400 years
tin can 50-100 years
soft drink can 200-500 years
monofilament fishing line 600 years
glass beverage bottle 1 million years
styrofoam never

Sources: Keep America Beautiful, Louisiana Department of Environmental Quality.