"RCO Economic Effectiveness The economic effectiveness of each Risk Control Option (RCO) is evaluated based upon: a) the Net Present Value (NPV) cost of its implementation and operation (incl. maintenance) through its lifetime (ΔC) and b) its risk reduction (ΔR) over the same period. Depending on the nature of risks addressed, the RCO acceptance and prioritization is weighed against the Implied Cost of Averting a Fatality (ICAF) or the Cost of Averting a Tonne of oil Spilled (CATS). Although many proposals exist for appropriate optimum values of ICAF no universally accepted values are currently established. However, the value of $ 3 million as suggested for use by IMO continues to be a valid proposal . Furthermore, , and presented an environmental criterion equivalent to ICAF which assesses the RCO's economic effectiveness towards the prevention of accidental releases of oil to the marine environment. This criterion was named CATS and its suggested threshold value was $ 60,000 per ton. A specific RCO for reducing environmental risk should be recommended for adoption provided its ΔC/ΔR value is below that of CATS, otherwise that particular RCO should not be recommended ."