It's six of one and half a dozen of the other really! The plastic that food comes in is of the very low dioxin transference type - as is the cling film we can buy as long as it says suitable for use in the microwave. It's when the plastic is heated that causes the problem, and especially if it comes into contact with fatty foods - so if using cling film in the microwave, don't let it touch the food. anyway, back to your point, you take it out of the packaging it came in, what would you cover it with? Even in the fridge, it needs covering - the rule is, the bigger the lump of meat, the longer it lasts, so cold meats should really be used the same day if bought at a deli, but if it's pre-packed it's fine until the use-by date. I leave large joints in the bottom of the fridge covered in greaseproof and a new 'J' cloth - but no longer than overnight.
Warning: - Don't leave 'PET' water or pop bottles on warm window ledges or in the car so they get warm, they do release dioxins into the drink.