The enforcement of environmental laws has led to a new growth industry in real estate, one composed of experts in the field of environmental due diligence. Environmental laws and regulations are a critical part of any real estate transaction , whether ＿＿（13）＿＿ , sale, lease, or financing process. The parties need to know whether the underlying real estate is contaminated and, if so, what effect contamination will have on the economics of the deal. Environmental due diligence has become important for a number of reasons. ＿＿（14）＿＿ , for example, need to determine the costs associated with environmental contamination, such as leakage from an underground fuel tank. ＿＿（15）＿＿ need to know whether contamination will prevent development of the property or make it prohibitively expensive—asbestos abatement costs, for example, can significantly increase the cost of renovation work. In all these cases, the parties need to know whether or not there is contamination and the estimated ＿＿（16）＿＿ cost. Due diligence is not a new concept. For years, cautious purchasers of real estate, governed by the principle ''let the buyer beware,''have undertaken ＿＿（17）＿＿ investigations. But the focus was different in earlier days. State and federal environmental laws enacted in the 1980s changed the focus of this type of investigation. These laws ＿＿（18）＿＿ potential cleanup liability upon owners and operators of property, regardless of whether the parties were involved in causing the contamination.