title: Evaluation of potential human health effects associated with the agricultural uses of 1,3-D: Spatial and temporal stochastic risk analysis.
abstract: Dow AgroSciences (DAS) markets and sells 1,3-Dichloropropene (1,3-D), the active ingredient in Telone®, which is used as a pre-plant soil fumigant nematicide in economically important crops in California. 1,3-D has been regulated as a "probable human carcinogen" and the California Department of Pesticide Regulation limits use of 1,3-D based on human health risk assessments for bystanders. This paper presents a risk characterization for bystanders based on advances in the assessment of both exposure and hazard. The revised bystander risk assessment incorporates significant advances: 1) new data on residency duration and mobility in communities where 1,3-D is in high demand; 2) new information on spatial and temporal concentrations of 1,3-D in air based on multi-year modeling using a validated model; and 3) a new stochastic spatial and temporal model of long-term exposures. Predicted distributions of long-term, chronic exposures indicate that current, and anticipated uses of 1,3-D would result in lifetime average daily doses lower than 0.002mg/kg/d, a dose associated with theoretical lifetime excess cancer risk of <10(-5) to >95% of the local population based on a non-threshold risk assessment approach. Additionally, examination of 1,3-D toxicity studies including new chronic toxicity data and mechanism of action supports the use of a non-linear, threshold based risk assessment approach. The estimated maximum annual average daily dose of <0.0016mg/kg/d derived from the updated exposure assessment was then compared with a threshold point of departure. The calculated margin of exposure is >1000-fold, a clear indication of acceptable risk for human health. In summary, the best available science supports 1,3-D's threshold nature of hazard and the revised exposure assessment supports that current agricultural uses of 1,3-D are associated with reasonable certainty of no harm, i.e., estimated long-term exposures pose insignificant health risks to bystanders even when the non-threshold approach is assumed.
authors.affiliation: risksciences.net, LLC, 10009 Wisakon Trail, Manassas, VA 20111, USA. Electronic address: jeff@risksciences.net.
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Driver
authors.affiliation: The Dow Chemical Company, 1803 Building, Midland, MI 48674, USA.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Price
authors.affiliation: Dow AgroSciences, LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA.
authors.forename: Ian
authors.initials: I
authors.lastname: Van Wesenbeeck
authors.affiliation: risksciences.net, LLC, 5150 Fair Oaks Blvd., Ste. 101-370, Carmichael, CA 95608, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Ross
authors.affiliation: Dow AgroSciences, LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Gehen
authors.affiliation: Larry R. Holden, Statistical Consulting, 1403 Post Oak Circle, College Station, TX, USA.
authors.forename: Larry R
authors.initials: LR
authors.lastname: Holden
authors.affiliation: The Dow Chemical Company, 1803 Building, Midland, MI 48674, USA.
authors.forename: Bryce
authors.initials: B
authors.lastname: Landenberger
authors.affiliation: Dow AgroSciences, LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA.
authors.forename: Kerry
authors.initials: K
authors.lastname: Hastings
authors.affiliation: Dow AgroSciences, LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA.
authors.forename: Zhongyu June
authors.initials: ZJ
authors.lastname: Yan
authors.affiliation: Dow AgroSciences, LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Rasoulpour
mesh_terms: D000383:Agriculture; D000498:Allyl Compounds / Q000633:toxicity*; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000633:toxicity*; D007306:Insecticides / Q000633:toxicity*; D018570:Risk Assessment; D013269:Stochastic Processes
chemical_list: D000498:Allyl Compounds; D006843:Hydrocarbons, Chlorinated; D007306:Insecticides; C023891:1,3-dichloro-1-propene
keywords: 1,3-dichloropropene; Exposure assessment; Population mobility; Probabilistic model; Residency duration