Letter to the Editor

The recent paper by Craan and Haines (1998) sparked myinterest because it provides scarce and greatly needed data onhalf-lives of organochlorines (OCs) in humans. The authorspoint out the steady decline of some, but not all, OCs in milkduring the past 20–25 years. For DDT and TCDD, half-livescan be estimated from these Canadian data, and the results areremarkably similar to clearance times calculated using otherpopulation averages and individual data. Their average concen-trations in breast milk from 1975 forward give a half-life of 6.3years for DDT (bis(4-chlorophenyl)-1,1,1—trichloroethane)residues (based on 6 time-points) and between 6 and 12 yearsfor TCDD (2,3,7,8-tetrachlorodibenzodioxin; based on 2–3time-points). Similar data from adipose tissue levels in theUnited States (Kutzet al. 1991; also plotted in Wolff 1995)provide a half-life estimate of 5.7 years for DDT residues(based on 10 or 11 annual mean values between 1970 and1983). These half-life estimates agree with unpublished datafrom our laboratory on sequential measurements of DDE(bis(4-chlorophenyl)-1,1—dichloroethene, the primary residueof DDT) among approximately 400 individuals in two separatestudies (manuscripts in preparation). Likewise, the TCDDhalf-lives in breast milk determined from the Canadian popula-tion means are consistent with several studies of exposedindividuals, i.e., 7–10 years (Longneckeret al. 1997; Flesch-Janys et al. 1996). Peak DDT levels in Canadian adults,approximately 5000 ng/g lipid in 1967, were predicted byCraan and Haines to decline to 90 ng/g (parts per billion on alipid basis) by the year 2001. The U.S. average in adiposetissue of greater than 10,000 ng/g DDT in 1967 (Kutzet al.1991) should decline to 200 ng/g (ppb) by the next century.

These findings may have public health and regulatory implica-tions and will be useful for epidemiologic studies that aremeasuring DDT.

Mary S. WolffDepartment of Community MedicineEnvironmental and Occupational MedicineBox 1057, 1 Gustave L. Levy PlaceMount Sinai School of MedicineNew York, New York 10029, U.S.A.

References

Craan AG, Haines DA (1998) Twenty-five years of surveillance forcontaminants in human breast milk. Arch Environ ContamToxicol 35:702–710

Flesch-Janys D, Becher H, Gurn P, Jung D, Konietzko J, Manz A,Papke O (1996) Elimination of polychlorinated dibenzo-p-dioxins and dibenzofurans in occupationally exposed persons. JToxicol Environ Health 47:363–378

Longnecker MP, Rogan WJ, Lucier G (1997) The human health effectsof DDT (dichlorodiphenyl-trichloroethane) and PCBs (polychlo-rinated biphenyls) and an overview of organochlorines in publichealth. Annu Rev Publ Health 18:211–244

Kutz FW, Wood PH, Bottimore DP (1991) Organochlorine pesticidesand polychlorinated biphenyls in human adipose tissue. RevEnviron Contam Toxicol 120:1–82

Wolff MS (1995) Pesticides: how research has succeeded and failed ininforming policy: DDT and the link with breast cancer. EnvironHealth Persp 103(Suppl 6):87–91

Arch. Environ. Contam. Toxicol. 36, 504 (1999) A R C H I V E S O F

EnvironmentalContaminationa n d Toxicologyr 1999 Springer-Verlag New York Inc.