CC - Agendas - City Council - REGULAR - 8/14/2018

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8.C.e Regulatory History Human Health Assessment Diquat dibromide is the common name for 6,7-dihydrodipyrido (1,2- a:2',1'-c) pyrazinediium dibromide. The manufacture of diquat dibromide may result in the formation of ethylene dibromide (EDB) as a process impurity. EDB is considered a carcinogen, and all pesticide uses have been cancelled. EPA assessed the potential exposure risks of diquat dibromide and concluded in June 1986 that the presence of EDB does not pose a significant dietary risk, based on worst case assumptions. In addition, the registrant certified an upper limit of 10 parts per billion for EDB in diquat dibromide, and demonstrated that EDB does not persist and will slowly dissipate over time in diquat dibromide. EPA issued a Registration Standard for diquat dibromide in June 1986 (NTIS #PB87-105490). A 1991 Data Call -In required additional toxicology, ecological effects, environmental fate, and residue chemistry data. Currently, 43 products containing the active ingredient diquat dibromide are registered and marketed under the trade name Diquat. Toxicity In studies using laboratory animals, diquat dibromide has been shown generally to be of moderate toxicity. It can cause slight to severe eye irritation and has been placed in Toxicity Category II (the second highest of four categories) for acute dermal and eye irritation effects. It is slightly acutely toxic by the oral and inhalation routes and has been placed in Toxicity Category III for these effects. Diquat dibromide causes slight dermal irritation and has been placed in Toxicity Category IV for this effect. It is not a skin sensitizer. A supplemental subchronic dermal toxicity study using rabbits indicated that diquat dibromide is toxic via repeated dermal exposure. A second dermal study using rats resulted in high mortality, decreased food consumption and weight gain, congestion in the lungs, liver and kidneys, and dermal irritation at the application site. An inhalation study using rats resulted in increases in lung weight, lung/body weight and lung/brain weight, lung lesions, and mottling and reddening of the lungs in females; however, all effects except the latter were reversible. A second inhalation study using rats showed no effects on any of the parameters examined. A chronic feeding/carcinogenicity study using rats resulted in eye effects including lens opacity and severe cataracts. A feeding study using beagle dogs showed some incidence of cataracts, and decreased adrenal and epididymide weights in males. Another chronic feeding/cancer study using rats resulted in evidence of bone tumors. The Agency's Health Effects Division Reference Dose/Peer Review Committee evaluated the carcinogenic potential of diquat dibromide in March 1994 and classified it as a Group E carcinogen --a chemical for which there is evidence of non -carcinogenicity for humans --based on a lack of Attachment: EPA Facts (2109 : Dukes Root Control) 2 Packet Pg. 56