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

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8.C.e Environmental Assessment for commercial uses, and is limiting residential use to spot treatments with label directions warning these users not to touch treated plants until sprays have dried. Environmental Fate Diquat dibromide's primary route of environmental dissipation is strong adsorption to soil particles. Diquat does not hydrolyse or photodegrade and is resistant to microbial degradation under aerobic and anaerobic conditions. No major degradates have been isolated. When used as an aquatic herbicide, diquat dibromide is removed from the water column by adsorption to soil sediments, aquatic vegetation, and organic matter. Adsorbed diquat dibromide is persistent and immobile, and is not expected to be a ground- water contaminant. Ecological Effects Diquat dibromide is moderately toxic to birds in acute studies, and is slightly to moderately toxic on a subacute dietary basis. It is practically non- toxic to bees. In acute studies, diquat dibromide is slightly to moderately toxic to both cold and warm water fish. In fish early life stage studies, it ranges in toxicity from slightly to moderately toxic. It is slightly to highly toxic to both aquatic invertebrates and estuarine species. Additional studies are required to determine diquat dibromide's toxicity to nontarget aquatic and terrestrial plants. Ecological Effects Risk Assessment High acute risk to birds is not expected from use of diquat dibromide. However, the turf use exceeds EPA's level of concern for restricted use, and for endangered bird species feeding on short grass. Regarding chronic effects, birds feeding on diquat dibromide-contaminated food items may experience reproductive problems. Diquat dibromide will pose only a low overall risk to mammals. Effects, if they occur, should not result in significant ecological damage. However, the Agency is only moderately certain that nonendangered mammals are not at acute risk from diquat dibromide, which exceeds the restricted use level of concern for all uses except cantaloupes. The level of concern for endangered species is exceeded for all use patterns. Chronic risks to mammals are believed to be low. Diquat dibromide may pose acute or chronic risk to aquatic organisms, but the probability that exposure will occur is relatively low. It is therefore expected to pose only a minimal risk to aquatic organisms from exposure to runoff. Diquat dibromide does not cause adverse effects to freshwater fish. Freshwater invertebrates are not likely to be adversely affected by its use in the short term, but their reproductive success may be adversely effected. Drift from aerial spraying of diquat dibromide is likely to result in adverse effects to plants. The possibility of risk to non -target aquatic and terrestrial plants from aerial application from all sites is relatively high. Attachment: EPA Facts (2109 : Dukes Root Control) 5 Packet Pg. 59