Fetal metals

Shukla R. Bomschein RL, Dietrich KN, et al. 1987. Effects of fetal and early postnatal lead exposure on child s growth in stature—the Cincinnati lead study. In Lindberg SE, Hutchinson TC, eds. International Conference on Heavy Metals in the Environment, Vol. 1. New Orleans, LA, September. Edinburgh, UK CEP Consultants, Ltd., 210-212. 

Grossly elevated concentrations of dissolved copper produce teratogenicity in fish embryos. A significant number of malformed fish larvae came from eggs treated with 500 pg Cu/L (Birge and Black 1979). In studies with laboratory animals and elevated concentrations of copper salts, copper penetrates the placental barrier into the fetus intramuscular injection of 4 mg Cu/kg BW early in pregnancy adversely affects fetal central nervous system development (Aaseth and Norseth 1986). In humans, no definitive data are available on whether copper can cause birth defects however, incubation of human spermatozoa with metallic copper results in loss of sperm motility (Aaseth and Norseth 1986). 

Copper deficiency in humans and other mammals is characterized by slow growth, hair loss, anemia, weight loss, emaciation, edema, altered ratios of dietary copper to molybdenum and other metals, impaired immune response, decreased cytochrome oxidase activity, central nervous system histopathology, decreased phospholipid synthesis, fetal absorption, and eventually death (NAS 1977 Gallagher 1979 Kirchgessner et al. 1979 USEPA 1980 ATSDR 1990 Percival 1995). 

Iodides should not be used alone since the normal gland will escape from iodide blockade in 2-8 weeks. Chronic use in pregnancy is not recommended because it crosses placenta and cause fetal goitre. Iodide treatment results in high intrathyroidal iodide content that can delay the onset of thioamide therapy or delay the use for radioactive iodine therapy for weeks if not months. Adverse effects include Hodism which is rare and reversible. The clinical symptoms are acneiform rash, sialadenitis, mucous membrane ulceration, conjuctivitis, rhinor-rhoea, metallic taste and rarely anaphylactoid reaction. 

Developmental Effects. Based on the existing information, it is not known whether silver causes developmental toxicity in humans. No studies were found concerning developmental effects in humans after exposure to silver. However, a human study by Robkin et al. (1973) did investigate the possibility of a relationship between the concentration of this heavy metal in the tissue of fetuses and the occurrence of developmental abnormalities. These authors reported that the concentration of silver in the fetal liver of 12 anencephalic human fetuses was higher (0.75 0.15 mg/kg) than the values from 12 fetuses obtained either through therapeutic abortions (0.23 0.05 mg/kg), or in 14 spontaneously aborted fetuses (0.21 0.05 mg/kg). The concentration in 9 premature infants was 0.68 0.22 mg/kg. The authors could not determine if the higher concentrations of silver in anencephalic fetuses were associated with the malformation, or with fetal age. 

Robkin MA, Swanson DR, Shepard TH. 1973. Trace metal concentrations in human fetal livers. 

Exposure, Intake, and Effects of Toxic and Essential Elements Assessment of steroid hormone disruption in placenta as indicator tissue for monitoring fetal and maternal environment. Biomonitoring of metals is included with evaluation of dietary metal intake (European Commission 2004). 

Wide M. 1984. Effect of short-term exposure to five industrial metals on the embryonic and fetal development of the mouse. Environ Res 33 47-53. 

Several studies indicate that different methods cause adverse effects to embryonic and fetal tissues and eventually lead to the development of teratogenic effects. Metals are omnipresent in the living environment. A variety of anthropogenic activities (e.g., smelting metallic ore, industrial and metal fabrication, commercial application, burning of fossil fuels) have caused adverse effects to the developing fetus. In fact, notorious elements, such as cadmium, lead, and mercury, have been associated with injury and malformation to the growing embryo and fetus of animals and humans.65... 

The metal composition of native MTs depends on the natural source and/or on the previous exposure of the organism to metals. The inducible MT-1 and MT-2 isoforms isolated from adult and fetal human livers contain mainly zinc, while those isolated from adult human kidney contain mainly cadmium with some copper or zinc. It may be noted that in higher organisms MTs are the sole proteins in which cadmium accumulates naturally. Both mammalian tissue specific forms MT-3 and MT-4 contain zinc and copper. In contrast to MTs from mammalian sources, in which zinc, cadmium, and copper can be simultaneously bound, yeast (53 aa) and fungal (25 aa) MTs contain exclusively copper. Specific binding of cadmium or copper to different tissue specific MT forms in vivo has been encoimtered in the snail Helix pomatia. ... 

Heavy metals are routinely used in various manufacturing processes and are contained within many products commonly used by humans. Acts of terrorism have the potential to increase the environmental exposure of humans and animals to heavy metals by targeting industrial complexes and sewage treatment facilities. Because a number of heavy metals have the potential to affect different stages of reproductive function by different mechanisms of action, the adverse effects of metals on male and female reproduction and embryonic and fetal development will be discussed separately. 

Figure 4, A tightly packed, piled-up normal Syrian hamster fetal cell colony. Treatment with some of the metal carcinogens induced a higher incidence of these tightly packed/piled up normal colonies. This type of colony was also present in untreated cultures.

Cultures of secondary Syrian hamster fetal cells were prepared with 10 cells per 35-mm plates. Following a 24-hr period of attachment the monolayer was treated two times for two days with various concentrations of the metal compounds as shown in the figure. The metal compounds were then removed by washing the mono-layer extensively with saline A and the cultures were incubated for 18-21 days with fresh Dulbecco s medium supplemented with 10% fetal bovine serum. The cultures were refed two times per week. The plates were then fixed and stained as described in Methods. Acetone was used to sterilize the metal compound. The number of transformed foci was determined per plate. Each point shown in the mean SEM for at least six plates. 

Syrian hamster fetal cells were treated with the various metal compounds shown in the table for 8-8 days. The compounds were removed by washing the cells with saline A. The cells were trypsinized and 10,000 ceUs were replated with fresh inedia into 35-mm plates and allowed to proliferate for two weeks. The plates containing... 

Binding Component in Human Fetal Liver. Its Identification as Metal-lothionein, /. Biol. Chem. (1978) 253, 519-524. 

Very many chemicals are recognized teratogens in animals a significantly smaller subset of these is known or suspected to be developmental neurotoxicants in humans. Some of the more significant of the latter group include ethanol, which causes a constellation of effects ranging from fetal alcohol syndrome to alcohol-related neurodevelopmental disorder maternal smoking of tobacco (fetal tobacco syndrome) excess vitamins A and D heavy metals, particularly... 

Metallic Mercury. No association was demonstrated between inhalation exposure of the father and increased rates of major fetal malformations or serious childhood illnesses in a retrospective cohort study of workers at a U.S. DOE plant (Alcser et al. 1989). 

Absorbed metallic mercury crosses the placenta, and the fetal blood may concentrate mercury to levels 10 or more times the levels found in the maternal blood. Therefore, the developing fetal nervous system may be quite sensitive to maternal exposures to mercury vapors. 

Developmental Toxicity. Occupational exposure to metallic mercury in males did not result in statistically significant effects on malformations or the number of children bom (Alcser et al. 1989 Lauwerys et al. 1985). The results from an inhalation developmental rat study (Baranski and Szymczyk 1973) suggest that metallic mercury vapors may cause a higher incidence of fetal malformations, resorptions, and deaths. Dermal studies on metallic mercury in humans and animals were not available. Additional well-conducted inhalation and dermal studies on metallic mercury in animals are needed to evaluate the potential for adverse developmental effects to humans from mercury. 

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