[The concept of the MPEL: pro and con].

A conception, some principles of determination and limits of maximum concentration limit (MCL) of chemical compounds in environment are considered. The experimental results confirming the threshold character of pollution influence upon plants and animals are discussed. It is shown that the MCL conception has a scanty applicability and doesn't defend the man from environmental pollutions. A conclusion about the necessity of alternative approaches to the determination of limiting load on ecosystems is made.