Check the FAO/WHO and EU websites.

http://www.fao.org/home/en/

http://www.who.int/en/

Check the table for maximum daily tolerable limits for human intake

http://www.occeweb.com/og/metals-limits.pdf

http://www.foodstandards.gov.au/publications/documents/20thATDS_SUPPL_Part1a.pdf

Soil quality guidlines for the protection on environment and human health

http://st-ts.ccme.ca/en/index.html

Thank you for kind responses! They are very helpful!

As dear Prof C.A. (Kees) Kan mentioned please follow the WHO / FAO and EU standards .

If it can help please read my articles about mushrooms !

Ziarati, P., Rabizadeh, H., Mousavi, Z, Asgarpanah, J., Azariun, A. 2013. The Effect of Cooking method in Potassium, Lead and Cadmium Contents in Commonly Consumed Packaged mushroom (Agaricus bisporus) in Iran. IJFAS Journal, 2, pp. 728-733.

1 Parisa Ziarati, 2 Seyedeh- Shima Ghasemynezhad-Shanderman MINERAL CONTENTS IN PLEUROTUS (OYSTER MUSHROOM): ASSOCIATION OF COOKING METHOD .

Best regards

It's available at FAO/WHO website

http://www.occeweb.com/og/metals-limits.pdf

Thank you so much! I will go to your articles.

Thank you for all of kind responses!