Article pubs.acs.org/est
Occurrence, Distribution, and Accumulation of Pesticides in Exterior Residential Areas Weiying Jiang,*,†,‡ Jeremy L. Conkle,†,§ Yuzhou Luo,‡ Juying Li,†,∥ Karen Xu,⊥ and Jay Gan† †
Department of Environmental Sciences, University of California, Riverside, Riverside, California 92521, United States California Department of Pesticide Regulation, Sacramento, California 95812, United States § Department of Physical & Environmental Sciences, Texas A&M UniversityCorpus Christi, Corpus Christi, Texas 78412, United States ∥ College of Energy and Environmental Engineering, Shenzhen University, Shenzhen, Guangdong 518060, People’s Republic of China ⊥ Department of Statistics, University of California, Riverside, Riverside, California 92521, United States ‡
S Supporting Information *
ABSTRACT: Pesticides are commonly applied around residential homes, but their occurrence on exterior surfaces (e.g., pavement) has not been thoroughly evaluated. We collected 360 dust samples from curbside gutters, sidewalks, and street surfaces at 40 houses in southern California to evaluate pesticide occurrence on urban paved surfaces as well as their spatial and temporal distributions. Pesticides and select degradates were ubiquitously detected in dust, with the median concentration of total target analytes at 85 μg kg−1. A total of 75% of samples contained at least five pesticides. As a result of recurring pesticide applications, concentrations increased throughout the summer. The pyrethroids bifenthrin and permethrin accounted for 55% of total pesticides detected in the dust. The highest concentrations in dust were found on the sidewalk and in the gutter. Relative to indoor environments, human exposure risk to pesticides on paved surfaces was estimated to be lower, with the highest potential oral and dermal exposure predicted to be 38 ng day−1 for permethrin. The ubiquitous detection of pesticides on residential outdoor surfaces and the fact that the exterior concentrations did not correlate to the indoor areas highlight the necessity to measure pesticides in both indoor and outdoor areas for complete residential pesticide risk assessment.
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INTRODUCTION In 2011, professional applicators in California used 210 500 kg of pyrethroids and fipronil for residential insect control, a 45% increase from 144 794 kg in 2010.1 This large amount is likely an underestimate because it does not account for products sold over the counter to homeowners. Although applied around private residences to control insects, some of these compounds are considered potential human carcinogens and/or endocrine disruptors that can stimulate cancer cell proliferation at 10 μM.2−6 In addition, rainfall and irrigation-induced surface runoff can transfer these pesticides to receiving basins, where some of these pesticides can accumulate at levels toxic to nontarget species of crustaceans, fish, reptiles, and birds.7,8 Numerous studies have documented the presence of pesticides inside private residences.2,9−11 For instance, on residential indoor dust, the pyrethroid permethrin was found in ∼100% samples with maximum concentrations over 10 mg kg−1.9 However, pesticide occurrence outside residential homes is not well-known. Solid particles (i.e., dust) on outdoor paved surfaces may serve as carriers for pesticide uptake by humans through ingestion or dermal sorption and for pesticide transfer to natural waters through water runoff or wind. Outdoor dust is also an important source of dust inside homes.12 Therefore, it is © 2016 American Chemical Society
imperative to survey exterior dust to complete knowledge on residential pesticide contamination and provide information for mitigation. In comparison to the relatively stable climate of indoor areas, pesticides on outdoor surfaces are influenced by variable environmental conditions (e.g., wind, temperature, rain, and solar radiation), which likely affects their persistence and accumulation at a rate different from indoor areas. For example, levels of fipronil on parking spaces (
