Hmm, most low cost fruit juices sold in tetra packs or similar throughout the world are derived from a concentrate. Those that aren't are generally only sold in chilled cabinets.
So what does concentrate mean? Well, basically it means that the juice obtained from the fruit is boiled near source to reduce the water it contains. The water is emitted as steam. The more viscous juice that results is then generally frozen and shipped to the country of sale. At the processing plant within that country, water is added to the thawed concentrate until the specific gravity returns to that of the juice when pressed in the country of origin. Such a product has to legally declare that it is "from concentrate" in most countries nowadays.
If you are correct that juice from China or Argentina contains arsenic, then the processing outlined above will not remove the arsenic. The quantity however is likely to be extremely small although without further information, I cannot provide more accurate figures on toxicity.