National Drinking Water Database
Diquat in Arkansas
Diquat is a non-selective herbicide and dessicant used extensively for control of crop and aquatic weeds; it may cause cataracts. [read more]
Diquat is an herbicide that has been used extensively in the United States since the late 1950s to control both crop and aquatic weeds. It is nonselective, meaning that it does not spare 'nontarget' plants from its herbicidal effects. Diquat acts as a desiccant because it causes a leaf or an entire plant to dry out quickly (Extension Toxicology Network (EXTOXNET) 1993a). It is used on potatoes; as an aid in harvesting cotton, rapeseed and other oil seed crops; to wilt and dry out silage and hay for storage; a plant growth regulator and sugar cane-flowering suppressant. Diquat contaminates drinking water through runoff from agricultural applications (USEPA 2009b).
Typical symptoms of diquat poisoning in people include gastrointestinal tract ulcer, paralytic ilieus, shock, kidney failure, respiratory problems, seizures and coma (Schmidt 1999; Jones and Vale 2000). Thirteen of thirty people poisoned with diquat between 1968 and 1999 have died (Jones and Vale 2000).
The toxic effect found at the lowest dose in laboratory animals is cataracts. In the key study, 100 percent of rats had cataracts at the end of a two-year exposure at the highest dose tested (reviewed in Pirie 1969). Recently, scientists have discovered that diquat decreases growth of human brain cells (Slaughter 2002). In people, exposure to large amounts of diquat induces acute and persistent parkinsonism (Ellenhorn 1997).
The Most Polluted Communities in Arkansas
1 water utilities reported detecting Diquat in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies
Ranked by highest average Diquat level
|Rank||System||Population Served||Positive test results of total reported tests||Average Level|
|11,000||1 of 5||0.02 ppb|
(0 to 0.1 ppb)
Health Based Limits for Diquat
|California Public Health Goals||Defined by the State of California Office of Environmental Health Hazard Assessment (OEHHA) as the level of contaminant that is allowed in drinking water. For acutely toxic substances, levels are set at which scientific evidence indicates that no known or anticipated adverse effects on health will occur, plus an adequate margin-of safety. PHGs for carcinogens or other substances which can cause chronic disease shall be based solely on health effects without regard to cost impacts and shall be set at levels which OEHHA has determined do not pose any significant risk to health.||15 ppb|
|Maximum Contaminant Limit (MCL)||The enforceable standard which defines the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to health-based limits (Maximum Contaminant Level Goals, or MCLGs) as feasible using the best available analytical and treatment technologies and taking cost into consideration. Source: U.S. Environmental Protection Agency.||20 ppb|
|Maximum Contaminant Limit Goal (MCLG)||A non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.||20 ppb|
|Drinking Water Equivalent Level||A lifetime exposure concentration protective of adverse, noncarcinogenic health effects, that assumes all of the exposure to a contaminant is from drinking water. Source: U.S. Environmental Protection Agency.||20 ppb|
Violation Summary for Diquat in Arkansas
There are no violations reported for this contaminant in Arkansas