Food processing can itself produce contaminants due to chemical reactions. One group of process contaminants is the chloropropanols, of which 3-MCPD is the most commonly occurring and well known. 3-MCPD is a potential carcinogen and so its presence in food is regulated, in EU legislation EC 1881/2006 with a maximum level of 20 μg/kg in foods. There is also a advised tolerable daily intake of 2 μg/kg body weight.
3-MCPD (3-monochloropropane-1,2-diol) was first detected in hydrolysed vegetable protein (HVP - a seasoning ingredient), soy sauce and similar foods in 1978. It is formed as a reaction product of hydrochloric acid with triacylglycerols, phospholipids and glycerol from the residual vegetable oil.
EFSA has established a tolerable daily intake (TDI) for 3-MCPD which has been calculated as 0.8 micrograms per kilogram of body weight per day (μg/kg bw/day) for 3-MCPD and its fatty acid esters based on evidence linking this substance to organ damage in animal tests