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

Home

8.C.e exposed subgroup, non -nursing infants less than one year old, has an ARC which represents 49% of the RID. Diquat dibromide's chronic dietary risk is therefore considered minimal. Occupational and Residential Exposure Based on current use patterns, workers (mixers, loaders, applicators, and other handlers) may be exposed to diquat dibromide during and after application in agricultural and other settings. During large-scale applications, the highest potential exposure and risks are to mixers and loaders using open systems to support aerial applications (their dermal Margin of Exposure (MOE) is 71, less than the 100-fold margin considered acceptable). Using closed systems, their dermal MOE is 400. EPA therefore is requiring closed mixing/loading of diquat dibromide for aerial applications. For applicators participating in large-scale applications and for all workers (including homeowners) participating in small-scale applications, MOEs are greater than 100. Post -application exposure to diquat dibromide residues on treated foliage is a concern. For uses within the scope of the Worker Protection Standard for Agricultural Pesticides (WPS), EPA is requiring a longer interim Restricted Entry Interval (REI) and more stringent personal protective equipment (PPE) than usual, to reduce potential exposure and risk (see Risk Mitigation below). For uses outside the scope of the WPS, post -application exposure risks also are posed. For example, golf course workers who have substantial physical contact with treated turf have a MOE of 13, 24 hours after application. At four days post -application, the MOE rises to 105. Therefore, a four -day reentry interval is being recommended for these workers. To reduce the potential for post -application residential exposure, spot treatments will be acceptable but broadcast treatments will be prohibited. Swimmers may be exposed to diquat dibromide residues in treated lakes and ponds, however their estimated MOE of 1,250 is acceptable. Human Risk Assessment Diquat dibromide is of moderate acute toxicity causing acute dermal toxicity and primary eye irritation (Toxicity Category II). It is classified as a Group E carcinogen, indicating that it poses no known cancer risk for humans. Diquat dibromide causes developmental and reproductive toxicity at the highest dose levels tested. Human incident data from California and other sources were considered in evaluating diquat dibromide's risks. Although people may be exposed to residues of diquat dibromide through their diets, the chronic dietary risk from such exposure is minimal. EPA is concerned about worker exposure to diquat dibromide during aerial spray operations, and is requiring use of closed systems to mitigate potential risks. The Agency also is concerned about post-application/reentry exposure for uses both within and outside the scope of the WPS. EPA therefore is imposing stringent reentry restrictions and protective clothing requirements Attachment: EPA Facts (2109 : Dukes Root Control) 4 Packet Pg. 58