title: Consumption of pesticide-treated wheat seed by a rural population in Malawi.
abstract: An outbreak of typhoid fever in rural Malawi triggered an investigation by the Malawi Ministry of Health and the Centers for Disease Control and Prevention in July 2009. During the investigation, villagers were directly consuming washed, donated, pesticide-treated wheat seed meant for planting. The objective of this study was to evaluate the potential for pesticide exposure and health risk in the outbreak community. A sample of unwashed (1430 g) and washed (759 g) wheat seed donated for planting, but which would have been directly consumed, was tested for 365 pesticides. Results were compared with each other (percentage change), the US Environmental Protection Agency's (EPA) health guidance values and estimated daily exposures were compared with their Reference dose (RfD). Unwashed and washed seed samples contained, respectively: carboxin, 244 and 57 p.p.m.; pirimiphos methyl, 8.18 and 8.56 p.p.m.; total permethrin, 3.62 and 3.27 p.p.m.; and carbaryl, 0.057 and 0.025 p.p.m.. Percentage change calculations (unwashed to washed) were as follows: carboxin, -76.6%; pirimiphos methyl, +4.6%; total permethrin, -9.7%; and carbaryl -56.1%. Only carboxin and total permethrin concentration among washed seed samples exceeded US EPA health guidance values (285 × and seven times, respectively). Adult estimated exposure scenarios (1 kg seed) exceeded the RfD for carboxin (8 × ) and pirimiphos methyl (12 × ). Adult villagers weighing 70 kg would have to consume 0.123, 0.082, 1.06, and 280 kg of washed seed daily to exceed the RfD for carboxin, pirimiphos methyl, permethrins, and carbaryl, respectively. Carboxin, pirimiphos methyl, permethrins, and carbaryl were detected in both unwashed and washed samples of seed. Carboxin, total permethrin, and carbaryl concentration were partially reduced by washing. Health risks from chronic exposure to carboxin and pirimiphos methyl in these amounts are unclear. The extent of this practice among food insecure communities receiving relief seeds and resultant health impact needs further study.
authors.affiliation: Division of Environmental Hazards and Health Effects, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia 30341, USA. jschier@cdc.gov
authors.forename: Joshua G
authors.initials: JG
authors.lastname: Schier
authors.forename: James J
authors.initials: JJ
authors.lastname: Sejvar
authors.forename: Emily
authors.initials: E
authors.lastname: Lutterloh
authors.forename: Andrew
authors.initials: A
authors.lastname: Likaka
authors.forename: Eugenia
authors.initials: E
authors.lastname: Katsoudas
authors.forename: Yelena D
authors.initials: YD
authors.lastname: Karaseva
authors.forename: Beth
authors.initials: B
authors.lastname: Tippett Barr
authors.forename: Yanique
authors.initials: Y
authors.lastname: Redwood
authors.forename: Stephan
authors.initials: S
authors.lastname: Monroe
mesh_terms: D004781:Environmental Exposure; D008295:Malawi; D010575:Pesticides / Q000633:toxicity*; D012424:Rural Population; D012639:Seeds; D014908:Triticum / Q000196:embryology*; D014481:United States; D014484:United States Environmental Protection Agency
chemical_list: D010575:Pesticides