On the 3rd May 2016 The European Food Safety Authority (EFSA) reported on the risks for human health from the use of MCPD as a food ingredient. EFSA concluded that cancer producing esters were, among the various oils available in chocolate manufacturing, found at the highest levels in palm oil.  Structurally altered palm oil is used in Cadbury's chocolate. Another major user of cancerous palm oil is Nutella. The reason palm oil, and not a safer oil such as rapeseed, is used is purely due to it being cheaper. As Reuters reported: "Any move away from palm oil would also have economic implications as it is the cheapest vegetable oil, costing around $800 a tonne, compared with $845 for sunflower oil and $920 for rapeseed oil, another possible substitute." A simple calculation will tell you that cancerous agents are being used in Cadbury's chocolate just to save $45 a tonne if, for example, the safer sunflower oil were to be used.

EFSA report: https://www.efsa.europa.eu/en/efsajournal/pub/4426

Reuters article: http://www.reuters.com/article/us-italy-ferrero-nutella-insight-idUSKBN14V0MK