To the Editor:
Industrial countries have ceased using dichlorodiphenyl trichloroethane (DDT), but this pesticide is still being employed in agriculture and for malaria control in the developing world. Since the major DDT metabolite, 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (p,p ′-DDE), accumulates in body fat and is a potent androgen receptor antagonist, 1 it has been suggested that exposure to this compound might affect reproductive function in men. 2 We studied relations between p,p ′-DDE body burden, androgen status, and reproductive function in young men from the state of Chiapas (Mexico), where malaria is endemic and DDT is sprayed in houses to control the disease vectors.
We recruited 24 young men (mean age = 21 years; range = 16–28) not occupationnally exposed to DDT. They provided a blood sample for the determination of DDT compounds in serum lipids by high-resolution gas chromatography with electron capture detection. Testosterone (total and bioavailable), sex hormone-binding globulin (SHBG), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) concentrations were also determined in serum using ELISA or RIA assays. In addition, participants provided a semen sample for standard andrological evaluation.
The mean concentration of p,p ′-DDE in serum lipids was 77.9 mg/kg (range = 17.0–177.2), a value some 350-fold greater than that documented by the same laboratory in Canadians exposed to background environmental levels. 3 We found that p,p-DDE concentration was positively correlated to serum SHBG concentration (Fig. 1A; Spearman’s r = 0.41) and negatively correlated to the bioavailable/total testosterone ratio (Fig. 1B; r = −0.47). Moreover, p,p ′-DDE concentration was inversely correlated to both semen volume (Fig. 1C; r = −0.47) and sperm count (Fig. 1D; r = −0.42).
These findings constitute the first evidence that a high p,p ′-DDE body burden may alter androgen status and reproductive function in men. In view of the controversy stirred by the United Nations Environmental Programme initiating negotiations for a global ban on DDT, 4,5 our results emphasize the need to monitor closely populations chronically exposed to high doses of DDT for the occurrence of subtle reproductive effects.
Mauricio Hernández Avila
Carlos Villanueva Díaz
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3. Lebel G, Dodin S, Ayotte P, Marcoux S, Ferron LA, Dewailly É. Organochlorine exposure and the risk of endometriosis. Fertil Steril 1998; 69: 221–228.
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5. Attaran A, Roberts DR, Curtis CF, Kilama WL. Balancing risks on the backs of the poor. Nat Med 2000; 6: 729–731.