| Associations between Plasma DDE Levels and Immunologic Measures in African-American Farmers in North Carolina Glinda S. Cooper,1 Stephen A. Martin,2,3 Matthew P. Longnecker,1 Dale P. Sandler,1 and Dori R. Germolec4 1Epidemiology Branch, National Institute of Environmental Health
Sciences, National Institutes of Health, Department of Health and Human Services,
Research
Triangle Park, North Carolina, USA; 2University of Michigan School
of Public Health, Ann Arbor, Michigan, USA; 3Cook County Department
of Public Health, Chicago, Illinois, USA; 4Laboratory of Molecular
Toxicology, National Institute of Environmental Health Sciences, National Institutes
of Health, Department of Health and Human Services, Research Triangle Park, North
Carolina, USA Abstract
Experimental studies in rodents demonstrate evidence of immunosuppressive effects of dietary exposure to DDT [2,2-bis(p-chlorophenyl) -1,1,1-trichloroethane], but human data pertaining to immunomodulating effects of DDT exposure are limited. In this study we examined the association between the persistent organochlorine breakdown product 1,1-dichloro-2,2,bis(p-chlorophenyl) ethylene (p,p´-DDE) and immunologic measures using blood samples in a relatively highly exposed population of farmers in the United States. Levels of serum immunoglobulin A (IgA) and IgG and the prevalence of antinuclear antibodies in relation to plasma p,p´-DDE levels were evaluated in samples from 137 African-American male farmers (30-88 years of age ; median, 64 years) . Participants were recruited through black churches in four rural counties in eastern North Carolina. Data collection included a telephone interview pertaining to farming practices and health history, and one blood sample was collected from each participant. Linear and logistic regression, adjusting for age, cholesterol, triglycerides, smoking status, and years of any kind of pesticide use, was used to assess the association between immunologic parameters and plasma levels of p,p´-DDE. The median plasma p,p´-DDE concentration was 7.7 µg/L (range, 0.6-77.4 µg/L) . There was no association between p,p´-DDE and IgA in any of the models. IgG levels decreased with increasing p,p´-DDE levels, with a statistically significant decrease of approximately 50% in the highest two categories of exposure ( 6.0 µg/L) compared with values of < 3.0 µg/L. Sixteen (12%) were positive for antinuclear antibodies. The prevalence of antinuclear antibodies was somewhat elevated in the highest category of p,p´-DDE exposure (odds ratio, 1.9 ; 95% confidence interval, 0.32-11.3 ; for 12.0 µg/L compared with < 3.0 µg/L p,p´-DDE) , but this difference was not statistically significant. These analyses provide evidence that p,p´-DDE modulates immune responses in humans. Key words: African American, autoantibodies, DDE, epidemiology, farmers, IgA, IgG, immunotoxicology. Environ Health Perspect 112:1080-1084 (2004) . doi:10.1289/ehp.6892 available via http://dx.doi.org/ [Online 3 May 2004]
Address correspondence to D.R. Germolec, Laboratory of Molecular Toxicology, NIEHS, MD C1-04, PO Box 12233, Research Triangle Park, NC 27709 USA. Telephone: (919) 541-3230. Fax: (919) 541-0870. E--mail: germolec@niehs.nih.gov We thank C. Parks and R. Luebke for thoughtful critique of the manuscript and R. Patterson for invaluable technical assistance. The authors declare they have no competing financial interests. Received 4 December 2003 ; accepted 3 May 2004.
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