DDT Spraying for Malaria Control and Reproductive Function in Mexican Men
Bibliographic record
Abstract
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). FIGURE 1: Correlations between p,p ′-DDE concentration in serum lipids and (A) serum concentration of sex-hormone binding globulin, (B) bioavailable to total testosterone ratio in serum, (C) semen volume, and (D) total sperm count. Data are for 21 (A, B) and 24 (C, D) young men from the state of Chiapas (Mexico).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. Pierre Ayotte Sylvie Giroux Éric Dewailly Mauricio Hernández Avila Paulina Farias Rogelio Danis Carlos Villanueva Díaz
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".