title: Longitudinal assessment of chlorpyrifos exposure and self-reported neurological symptoms in adolescent pesticide applicators.
abstract: OBJECTIVE
  Occupational exposure of organophosphorus pesticides, such as chlorpyrifos (CPF), in adolescents is of particular concern because of the potential vulnerability of the developing neurological system. The objectives of this study were to examine how neurological symptoms reported over the application season vary across time, whether these effects are reversible postapplication and if there are associations between CPF biomarkers and neurological symptoms in an adolescent study population.
  
  
  METHODS
  The longitudinal study was conducted in two agricultural districts of Menoufia Governorate, Egypt between April 2010 and January 2011.
  
  
  METHODS
  Male adolescent participants, including CPF applicators (n=57) and non-applicators (n=38), were recruited.
  
  
  METHODS
  Self-reported data for 25 neurological symptoms were collected at 32 time points over the 8-month period before, during and after the application season. Additionally, urine and blood samples were collected to measure urine trichloro-2-pyridinol (TCPy), a CPF-specific biomarker and blood cholinesterase activity.
  
  
  RESULTS
  Applicators and non-applicators report the highest numbers of symptoms during the application season, followed by a reduction in symptoms after the application ended. Applicators reported a greater percentage of neurological symptoms, relative to baseline, than non-applicators after accounting for potential covariates. Among the applicators, cumulative TCPy was positively and significantly associated with the average percentage of symptoms (B=4.56, 95% CI 3.29 to 5.84; p<0.001). Significant associations (p=0.03-0.07) between the change in butyrylcholinesterase activity from the preapplication to the postapplication season and several domains of neurological symptoms were also found, even after adjusting for potential covariates.
  
  
  CONCLUSIONS
  These observations demonstrate changes in the reporting of symptoms across the application season, showing an increase in symptom reporting during application and recovery following the end of pesticide application. These findings reinforce the growing concern regarding the neurotoxic health effects of CPF in adolescent applicators in developing countries and the need for developing and implementing intervention programmes.
authors.affiliation: Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa, USA.
authors.forename: Khalid
authors.initials: K
authors.lastname: Khan
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Ismail
authors.forename: Gaafar
authors.initials: G
authors.lastname: Abdel Rasoul
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Bonner
authors.forename: Michael R
authors.initials: MR
authors.lastname: Lasarev
authors.forename: Olfat
authors.initials: O
authors.lastname: Hendy
authors.forename: Manal
authors.initials: M
authors.lastname: Al-Batanony
authors.forename: Alice L
authors.initials: AL
authors.lastname: Crane
authors.forename: Steven T
authors.initials: ST
authors.lastname: Singleton
authors.forename: James R
authors.initials: JR
authors.lastname: Olson
authors.forename: Diane S
authors.initials: DS
authors.lastname: Rohlman
mesh_terms: D000293:Adolescent; D000328:Adult; D000383:Agriculture; D015415:Biomarkers / Q000097:blood / Q000652:urine; D002091:Butyrylcholinesterase / Q000097:blood; D002648:Child; D004390:Chlorpyrifos / Q000009:adverse effects*; D003906:Developing Countries; D004534:Egypt; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009422:Nervous System Diseases / Q000097:blood / Q000139:chemically induced*; D009784:Occupational Diseases / Q000097:blood / Q000139:chemically induced / Q000652:urine; D016273:Occupational Exposure / Q000009:adverse effects*; D010575:Pesticides / Q000009:adverse effects*; D011728:Pyridones / Q000652:urine; D057566:Self Report; D014937:Work; D055815:Young Adult
chemical_list: D015415:Biomarkers; D010575:Pesticides; D011728:Pyridones; C012587:3,5,6-trichloro-2-pyridinol; D002091:Butyrylcholinesterase; D004390:Chlorpyrifos