COMPARABILITY OF LARGE-SCALE STUDIES OF AGRICULTURAL CHEMICAL CONTAMINATION OF RURAL PRIVATE WELLS

Detection of agricultural chemicals in ground water has prompted numer ous studies. Federal. state, and regional studies were conducted in th e last 10 fears in order to assess the occurrence of agricultural chem icals in ground water. The results of the studies present the number o r percentage of samples with agricultural chemicals above the drinking water standard or health advisory levels as well as samples with dete ctions of one or more compounds, Data comparison from one state or reg ion to another are frequently referred to by regulatory and agency per sonnel involved in water quality and agriculture issues. Unless the hi story of pesticide use. method of chemical analyses, detection limits, statistical design of the sampling plan, well type, well depth, geolo gy of the formation material, and typical land use around the wellhead are known, such comparisons can be misleading. Reporting the limitati ons or presenting a disclaimer should be a key element for a study so that ''apples and oranges'' are not compared.