Polychlorinated dioxins, furans (PCDD/Fs), and polychlorinated biphenyls (PCBs) and their trends in Canadian human milk from 1992 to 2005

• Published in: Chemosphere (Oxford) 2014-05, Vol.102, p.76-86
• Main Authors: Ryan, John Jake, Rawn, Dorothea F.K.
• Format: Article
• Language: English
• Subjects: Adult; Animals; Benzofurans - analysis; Biological and medical sciences; Delivery. Postpartum. Lactation; Dibenzofurans, Polychlorinated; Dioxins - analysis; Environment. Living conditions; Female; Furans - analysis; Gynecology. Andrology. Obstetrics; Human milk; Humans; Lipids - chemistry; Maternal, fetal and perinatal monitoring; Medical sciences; Milk, Human - chemistry; Ontario; PCBs; PCDD/PCDFs; Polychlorinated Biphenyls - analysis; Polychlorinated Dibenzodioxins - analogs & derivatives; Polychlorinated Dibenzodioxins - analysis; Public health. Hygiene; Public health. Hygiene-occupational medicine; Quebec; Time Factors; Trends; WHO2005-TEQ; World Health Organization
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2013.12.065

•PCDDs, PCDFs, and PCBs were measured in more than 300 Canadian human milk collected from 1992 to 2005.•All concentrations decreased temporarily by a factor of greater than two.•Going back to 1981, all concentrations have decreased by a factor of four.•Variation in levels of POPs within Canada and between Canada and the USA was less than a factor of two. More than 300 samples of human milk were collected from individuals residing in various regions across Canada in the years 1992 to 2005. The milks were taken from the main populated areas east to west in southern Canada as well as from the region of Nunavik in northern Quebec and analysed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs). The concentrations, expressed in ngkg−1 milk lipid, show an overall decrease of virtually all compounds examined including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), World Health Organization 2005 toxic equivalents (WHO2005-TEQ) PCDD/PCDFs, WHO2005-TEQ dioxin-like PCBs (dl-PCBs), and total PCBs. Median values of 2,3,7,8-TCDD changed from about 1.5ngkg−1 milk lipid in 1992 to 0.8ngkg−1 in 2005 while the median WHO2005-TEQ PCDD/F fell from about 14–7ngkg−1 milk lipid in the same period. The concentrations of PCDD/Fs and PCBs in samples from Nunavik, which is in Arctic Quebec, were higher than those observed in milk from southern Quebec although this difference was not large. Over two time periods, milk samples from Hamilton, Ontario showed slightly higher levels of PCBs than Austin, Texas, USA – a North American city of similar size and development but with more than twice the PBDE exposure. When compared with earlier human milk data going back to the early 1980s, this large data set shows a steady decline of human exposure to POPs in Canada by a factor of about four times.