Skip to main content
NCBI home page
Occupational and Environmental Medicine logoLink to Occupational and Environmental Medicine
. 2002 Jul;59(7):434–441. doi: 10.1136/oem.59.7.434

A clinical neurological, neurophysiological, and neuropsychological study of sheep farmers and dippers exposed to organophosphate pesticides

G Jamal 1, S Hansen 1, A Pilkington 1, D Buchanan 1, R Gillham 1, M Abdel-Azis 1, P Julu 1, S Al-Rawas 1, F Hurley 1, J Ballantyne 1
PMCID: PMC1740317  PMID: 12107290

Abstract

Objectives: To classify clinical diseases of the subjects with abnormal indices of peripheral neuropathy identified in field studies of sheep farmers and dippers exposed to organophosphate pesticides. To explore what neuropsychological profiles, if any, may be associated with neurophysiological damage in these subjects.

Methods: A case-control study (79 subjects) nested within the cross sectional study (685 subjects) of sheep farmers from the field study. Three groups with no, possible, and probable or definite neuropathy according to field studies were recruited. Investigations comprised symptoms of neuropathy, neurologial signs, motor and sensory nerve conduction, electromyography, quantitative sensory testing, and neuropsychological tests.

Results: The incidence of clinical neuropathy increased from 7% in the no neuropathy group to 52% in the probable or definite neuropathy group based on nerve conduction measurements or presence of neurological signs. Sensory abnormalities were found more often than motor deficits. Small diameter nerve fibres were also affected more than large fibres.

Conclusions: The neuropathy is predominantly sensory and is characteristic of distal, chronic neuropathy with no acute features. Small fibre populations are affected more than large fibre populations. Increasing severity of neuropathy was associated with anxiety and depression as measured in the neuropsychological tests.

Full Text

The Full Text of this article is available as a PDF (124.3 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Ames R. G., Steenland K., Jenkins B., Chrislip D., Russo J. Chronic neurologic sequelae to cholinesterase inhibition among agricultural pesticide applicators. Arch Environ Health. 1995 Nov-Dec;50(6):440–444. doi: 10.1080/00039896.1995.9935980. [DOI] [PubMed] [Google Scholar]
  2. Beach J. R., Spurgeon A., Stephens R., Heafield T., Calvert I. A., Levy L. S., Harrington J. M. Abnormalities on neurological examination among sheep farmers exposed to organophosphorous pesticides. Occup Environ Med. 1996 Aug;53(8):520–525. doi: 10.1136/oem.53.8.520. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Buchanan D., Jamal G. A., Pilkington A., Hansen S. Clinical validation of methods of diagnosis of neuropathy in a field study of United Kingdom sheep dippers. Occup Environ Med. 2002 Jul;59(7):442–446. doi: 10.1136/oem.59.7.442. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. De Rojas T. C., Goldstein B. D. Lack of evidence for the size principle of selective vulnerability of axons in toxic neuropathies. I. The effects of subcutaneous injections of 2,5-hexanedione on behavior and muscle spindle function. Toxicol Appl Pharmacol. 1990 Jun 1;104(1):47–58. doi: 10.1016/0041-008x(90)90281-x. [DOI] [PubMed] [Google Scholar]
  5. Dyck P. J., Karnes J. L., Daube J., O'Brien P., Service F. J. Clinical and neuropathological criteria for the diagnosis and staging of diabetic polyneuropathy. Brain. 1985 Dec;108(Pt 4):861–880. doi: 10.1093/brain/108.4.861. [DOI] [PubMed] [Google Scholar]
  6. Fiedler N., Kipen H., Kelly-McNeil K., Fenske R. Long-term use of organophosphates and neuropsychological performance. Am J Ind Med. 1997 Nov;32(5):487–496. doi: 10.1002/(sici)1097-0274(199711)32:5<487::aid-ajim8>3.0.co;2-p. [DOI] [PubMed] [Google Scholar]
  7. Goldberg D. P., Hillier V. F. A scaled version of the General Health Questionnaire. Psychol Med. 1979 Feb;9(1):139–145. doi: 10.1017/s0033291700021644. [DOI] [PubMed] [Google Scholar]
  8. Hansen S., Jamal G. A., Weir A. I., Ballantyne J. P., Bissessar E. A. An instrument for measurement of thermal thresholds in man. Biosensors. 1987;3(6):391–401. doi: 10.1016/0265-928x(87)80020-2. [DOI] [PubMed] [Google Scholar]
  9. Jamal G. A., Hansen S., Weir A. I., Ballantyne J. P. An improved automated method for the measurement of thermal thresholds. 1. Normal subjects. J Neurol Neurosurg Psychiatry. 1985 Apr;48(4):354–360. doi: 10.1136/jnnp.48.4.354. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Jamal G. A., Hansen S., Weir A. I., Ballantyne J. P. The neurophysiologic investigation of small fiber neuropathies. Muscle Nerve. 1987 Jul-Aug;10(6):537–545. doi: 10.1002/mus.880100608. [DOI] [PubMed] [Google Scholar]
  11. Jamal G. A. Neurological syndromes of organophosphorus compounds. Adverse Drug React Toxicol Rev. 1997 Aug;16(3):133–170. [PubMed] [Google Scholar]
  12. Jamal G. A., Weir A. I., Hansen S., Ballantyne J. P. An improved automated method for the measurement of thermal thresholds. 2. Patients with peripheral neuropathy. J Neurol Neurosurg Psychiatry. 1985 Apr;48(4):361–366. doi: 10.1136/jnnp.48.4.361. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Lotti M., Becker C. E., Aminoff M. J. Organophosphate polyneuropathy: pathogenesis and prevention. Neurology. 1984 May;34(5):658–662. doi: 10.1212/wnl.34.5.658. [DOI] [PubMed] [Google Scholar]
  14. McConnell R., Keifer M., Rosenstock L. Elevated quantitative vibrotactile threshold among workers previously poisoned with methamidophos and other organophosphate pesticides. Am J Ind Med. 1994 Mar;25(3):325–334. doi: 10.1002/ajim.4700250303. [DOI] [PubMed] [Google Scholar]
  15. Pilkington A., Buchanan D., Jamal G. A., Gillham R., Hansen S., Kidd M., Hurley J. F., Soutar C. A. An epidemiological study of the relations between exposure to organophosphate pesticides and indices of chronic peripheral neuropathy and neuropsychological abnormalities in sheep farmers and dippers. Occup Environ Med. 2001 Nov;58(11):702–710. doi: 10.1136/oem.58.11.702. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Rosenstock L., Keifer M., Daniell W. E., McConnell R., Claypoole K. Chronic central nervous system effects of acute organophosphate pesticide intoxication. The Pesticide Health Effects Study Group. Lancet. 1991 Jul 27;338(8761):223–227. doi: 10.1016/0140-6736(91)90356-t. [DOI] [PubMed] [Google Scholar]
  17. Savage E. P., Keefe T. J., Mounce L. M., Heaton R. K., Lewis J. A., Burcar P. J. Chronic neurological sequelae of acute organophosphate pesticide poisoning. Arch Environ Health. 1988 Jan-Feb;43(1):38–45. doi: 10.1080/00039896.1988.9934372. [DOI] [PubMed] [Google Scholar]
  18. Steenland K., Jenkins B., Ames R. G., O'Malley M., Chrislip D., Russo J. Chronic neurological sequelae to organophosphate pesticide poisoning. Am J Public Health. 1994 May;84(5):731–736. doi: 10.2105/ajph.84.5.731. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Stephens R., Spurgeon A., Calvert I. A., Beach J., Levy L. S., Berry H., Harrington J. M. Neuropsychological effects of long-term exposure to organophosphates in sheep dip. Lancet. 1995 May 6;345(8958):1135–1139. doi: 10.1016/s0140-6736(95)90976-1. [DOI] [PubMed] [Google Scholar]
  20. Stokes L., Stark A., Marshall E., Narang A. Neurotoxicity among pesticide applicators exposed to organophosphates. Occup Environ Med. 1995 Oct;52(10):648–653. doi: 10.1136/oem.52.10.648. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Zigmond A. S., Snaith R. P. The hospital anxiety and depression scale. Acta Psychiatr Scand. 1983 Jun;67(6):361–370. doi: 10.1111/j.1600-0447.1983.tb09716.x. [DOI] [PubMed] [Google Scholar]

Articles from Occupational and Environmental Medicine are provided here courtesy of BMJ Publishing Group

RESOURCES