Cadmium placenta

The total body burden of cadmium is less than 1 pg at birth, which gradually increases with age, up to 50 years. At this age, one who has essentially been unexposed to cadmium may accumulate 20-30 mg of cadmium in the body (Medeiros et al., 1997). The biological half-time has been estimated to be 15-30 years in human beings (Piscator, 1982). The placenta acts only as a partial barrier against the fetal exposure. Before the formation of the placenta, cadmium reaches the embryo. Later, cadmium is deposited in the placenta, and there is limited passage of cadmium into the fetus. Moreover, there is only minimal cadmium excretion in breast milk (Gerhardsson and Skerfving, 1996). 

Roels HA, Hubermont G, Buchet J-P, et al. 1978. Placental transfer of lead, mercury, cadmium, and carbon monoxide in women III. Factors influencing the accumulation of heavy metals in the placenta and the relationship between metal concentration in the placenta and in maternal and cord blood. 

Tabacova, S., Baird, D.D., Balabaeva, I., Lolova, D., Petrove, I. (1994). Placental arsenic and cadmium in relation to lipid peroxides and glutathione levels in maternal-infant pairs from a copper smelter area. Placenta 15 873-81. 

Cadmium does not readily pass the blood-brain barrier, the blood-testis barrier or the placental barrier, but it accumulates in the placenta of animals and humans [14]. In humans, placental transfer of Cd seems to be very low and Cd is found to accumulate in the placenta [15,16]. 

Lagerkvist BJson, Sandberg S, Freeh W, Jin T, Nordberg GF. Is placenta a good indicator of cadmium and lead exposure Arch Environ Health 1996 112 151 -156. 

Goyer RA, Cherian MG. Role of metallothionein in human placenta and rats with cadmium exposure. In Cadmium in the human environment toxicity and carcinogenicity. Nordberg G, Herber R,Alessio E (editors). International Agency for Research on Cancer (lARC) Scientific Publications, Vol 118, Eyon 1992 p. 239-247. 

Cadmium is a classic cumulative poison that accumulates in the kidneys over a lifetime. It is transported in the blood by erythrocytes and by albumin, and it is stored mainly in the liver and kidneys as metallothionein (50-75% of the body burden). Cadmium binds to many proteins at the sulfate and carbonyl sites. The half-life of cadmium in these two organs may be as long as 30 years. The correlation between years of exposure and blood levels does not appear to be significant. Cadmium also accumulates in the bones and the placenta of pregnant women. 

Metallothionein in the gastrointestinal mucosa plays a role in the gastrointestinal transport of cadmium. Its presence in cells of the placenta impairs the transport of cadmium from maternal to fetal blood and across blood-brain barriers, but only when the concentration of cadmium is low. Newborns are virtually cadmium free, whereas zinc and copper are readily supplied to the fetus. Rapid renal concentration occurs mainly during the early years of life. 

Eisenmann CJ, Miller RK. 1994. The placental transfer and toxicity of selenite relative to cadmium in the human term perfused placenta. Placenta 15 883-985. 

Schramel P, Hasse S and Ovcar-Pavlu J (1988) Selenium, cadmium, lead, and mercury concentrations in human breast milk, in placenta, maternal blood, and the blood of the newborn. Biol Trace Elem Res 15 111-124. 

Herber, R.F.M., Roelofsen A.M., Hazelhoff Roelfzema, W., and Copius Peereboom-Stege-man, J.H.J. (1985). Direct determination of cadmium in placenta. Comparison with a destruction atomic absorption spectrometric method. Fresenius Z. Anal. Chem. 322 743-746. 

The full-term placenta samples collected at maternity hospitals in four regions of different environmental pollutants and traffic density in Slovakia were examined for cadmium (and lead) contents. The average cadmium concentrations from these regions were in range 0.0120-0.0221 mg/kg and placental contamination with... 

Bursa (1996) studied the population consisted of 40 pregnant women (living in the Silesia district over 10 years and non-professionally exposed to heavy metals) and their 40 newborns, who had perinatal period problems (mainly respiratory effort). The concentrations of cadmium in whole maternal blood and in cord blood of their newborns with different birth weight (BW) are shown in Table 20. The author concluded, that the placenta barrier between mothers and babies exist only in relation to cadmium transfer, independently of birth weight. 

Baranowska (1995) measured the concentrations of lead and cadmium in human placenta and in maternal and neonatal (cord) blood with the aim to assess the influence of the strongly polluted environment on the content of metals in tissues and on permeability of placenta to cadmium (and lead). The author found the following mean concentrations of cadmium 4.90 p.g/1 in venous blood, 0.11 mg/kg in human placenta, 1.13 p.g/1 in cord blood, and concluded, that the placenta is a better barrier for cadmium than for lead. 

Baranowska, 1., 199.3. Lead and cadmium in human placentas and maternal and neonatal blood (in heavily polluted area) measured by graphite furnace atomic absorption spectrometry. Occup. Environ. Med. 52, 229-232. 

Cadmium residue in placenta tissue and umbilical cord blood... 

Keywords Cadmium Placenta Umbilical cord blood Aerosediment... 

The occurrence of elevated cadmium concentrations in air determined by analysis of aerosediments (settlings from air) in the Kikinda and Novi Sad areas, and literature data on toxicological properties of cadmium have prompted the authors to monitor cadmium concentration in umbilical cord blood of newborn children and in placentas of puerperae residing in the Kikinda and Novi Sad areas before and during their pregnancy. 

Fig. 1 compares the cadmium concentration in placentas of puerperae from the Kikinda area in the period 1996-1997 with the mean cadmium concentration given by the World Health Organization (Environmental Health Criteria 134, Cadmium) of 0.0125 pg/g (WHO, 1992). Cadmium concentration in placentas of puerperae from the Kikinda Maternity Hospital ranged from 0.006 to 0.124 pg/g, the mean level being 0.061 pg/g. In one sample, the cadmium concentration was below the mean cadmium levels according to WHO. 

Figure i. Cadmium concentration in placenta samples from the Kikinda area. 

Based on the mean cadmium concentration in placentas of puerperae, a statistically significantly higher cadmium concentration in placentas of puerperae from Novi Sad in comparison with those from Kikinda can be seen (t — 2.76, P = 0.0075), which is illustrated in Fig. 3. 

Figs. 1 and 2 compare the cadmium concentration in placentas of puerperae who smoked before and during their pregnancy and those who did not smoke, with mean levels given in EHC-134 according to WHO. The mean cadmium concentration in... 

Comparing the results of cadmium concentration in placentas and blood of newborn children from the Kikinda area with those from the Novi Sad area, the reverse relationship is noticed (Figs. 3 and 6). In order to find an explanation for this, and based on knowledge from the literature that there is metabolic antagonism between cadmium and zinc at tissue level, and that zinc has an antitoxic affect in relation to cadmium. 

The results show that the mean annual concentrations of cadmium and zinc in air in the Kikinda area were considerably higher in the period than those in the Novi Sad area. The elevated levels of cadmium and zinc in air in the Kikinda area were reflected in cadmium and zinc concentrations in placenta and umbilical cord blood of newborn children from Kikinda this is shown in Table 2, which compares the cadmium and zinc concentrations in placenta and umbilical cord blood of newborn children from... 

Novi Sad. Such a relationship of cadmium concentration in placenta and umbilical cord blood of newborn children can be explained by the influence of zinc on the permeability of cadmium through the placenta (Forstner, 1980 Kagi and Hapke, 1984 Fergusson, 1990 Sandstead, 1997). 

Copius-Peereboom, J.W., de Voogt, P., van Hattum, B., van der Velde, W., Copius-Peereboom-Stegman, J.H.J., 1979. The use of the human placenta as a biological indicator for cadmium exposure. In International Conference on Management and Control of Heavy Metals in the Environment, London. CEP Consultants, Edinburgh, pp. 8-10. 

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