only one issue the brown website says that food wrap is ok - i thought it was unsafe as it has little holes in it
i believe food wrap and cling film are different compounds. Food wrap cannot contain polyvinyl chloride (it can transmit to foodstuffs and is carcenogenic).
this is what i found about 'plastic wrap', the US term for cling film (not foodwrap)
A variety of standard tests exist to ensure that plastic wrap is effective. The most important are tests for permeability, impact resistance, and tear strength.
Water vapor permeability is measured by filling a dish with calcium chloride, a highly water-absorbent substance. It is covered with a sample of plastic wrap and weighed. The dish is then placed in a chamber with a controlled temperature and humidity. After a measured amount of time the dish is weighed again. The increase in weight shows how much water vapor has passed through the plastic. This test can also be done by filling the dish with water instead of calcium chloride and measuring the decrease in weight to see how much water vapor has escaped. These tests are performed at 73°F (23°C) with a relative humidity of 50%, at 90°F (32°C) with a relative humidity of 50%, and at 100°F (38°C) with a relative humidity of 90%.