Median Percentage Detection concen- Maximum Human Percentage Agricultural of wells threshold tration of concen- health of wells pesticide Trade with MDL or MRL1 detections tration criteria2 over health usage Compound name detections (ug/L) (ug/L) (ug/L) (ug/L) criteria rank3 -------- ----- ---------- ---------- ---------- ------- -------- ----------- ------------ HERBICIDES Atrazine AAtrex 45 0.001 0.017 0.97 3 (mcl) 0 28 Simazine Princep 12 0.005 0.008 0.011 4 (mcl) 0 47 Metribuzin Lexone, Sencor 10 0.004 0.013 0.028 200 (ha) 0 12 Metolachlor Dual 10 0.002 0.003 0.009 100 (ha) 0 25 Alachlor Lasso 6 0.002 0.006 0.008 2 (mcl) 0 17 EPTC Eptam, Eradicane 6 0.002 0.006 0.012 -- -- 5 2,4-D several 4 0.035 0.275 0.54 70 (mcl) 0 16 Diuron Karmex, Direx 2 0.02 -- 2.0 10 (ha) 0 20 Bromacil4 Hyvar, Urox B 2 0.035 -- 1.8 90 (ha) 0 -- Ethalfluralin Sonolan 2 0.004 -- 0.09 -- -- 53 2,4-DB none 2 0.035 -- 0.06 -- -- 40 Bentazon Basagran 2 0.014 -- 0.07 20 (ha) 0 26 Prometon4 Pramitol 2 0.018 -- 0.005 100 (ha) 0 -- Linuron Lorox, Linex 2 0.002 -- 0.001 -- -- 30 INSECTICIDES Dieldrin Panoram D-31 4 0.001 0.01 0.013 0.002 (rsd) 4 discontinued DEGRADATION PRODUCTS Desethylatrazine none 37 0.002 0.007 0.12 -- -- NA 2,6-diethylanaline none 4 0.003 0.004 0.008 -- -- NA p,p'-DDE none 2 0.006 -- 0.001 0.1 (rsd) 0 NA FUMIGANTS AND ASSOCIATED COMPOUNDS 1,2-dichloropropane5,6 none 12 0.2 0.25 0.5 5 (mcl) 0 discontinued 1,2,2-trichloropropane5,7 none 8 0.2 0.26 0.55 -- -- NA EDB8 Bromofume 7 0.04 0.31 1.1 0.05 (mcl) 5 discontinued 1,2,3-trichloropropane5 none 6 0.2 0.5 1.0 -- -- NA 1,3-dichloropropane5 none 2 0.2 -- 0.5 -- -- NA Bromoform none 2 0.2 -- 0.12 -- -- NA1The MDL is reported for the herbicides, insecticides, and degradation products; the MRL is reported for the fumigants. 2Human health criteria are either the maximum contaminant level (MCL), set by the EPA to be the maximum concentration allowed in drinking water, the lifetime health advisory level (HA), which is the maximum concentration in drinking water that would not cause adverse human health effects, excluding cancer (based on a 150-pound adult consuming about 2 quarts of water per day for 70 years), or the risk-specific dose (RSD), which is the concentration that corresponds to an increase of a 1 in one million chance of developing cancer. 3Calculated from the amount of pesticide applied to irrigated row crops in the study area in tons per year out of 103 pesticides 4Nonagricultural herbicide 5Many of the chlorinated propanes are by-products of manufacturing 1,3-dichloropropene and may be present in 1,3-dichloropropene- based formulations such as Telone II and D-D 92. 61,2-dichloropropane was an active ingredient in some nematocide formulations (Telone, Shell D-D) until it was discontinued in 1976. 7Values for this compound are estimated. 8EDB(1,2-dibromoethane) was analyzed for in 41 wells.
Any use of trade names is for descriptive purposes only and does not imply endorsement by the U.S. Government.