Effects of abnormal lead content of water supplies on maternity patients. The use of a simple industrial screening test in ante-natal care in general practice

Potential human developmental toxicants and the role of animal testing in their identification and characterization

Some 50 chemicals have been identified from environmental, occupational, or therapeutic exposure data as being potential developmental toxicants in humans. The toxicity pattern of these chemicals in humans has been characterized and correlated with developmental toxicity end points in laboratory animal models in order to determine the relevance and predictiveness of the results of testing in animals in extrapolation to human data. In general, animal developmental toxicity data closely paralleled human outcomes, and while humans in most cases were more sensitive than animals, the data support the concept that, imperfections aside, studies in animals serve a vital role in the hazard identification process.

Transplacental movement of inorganic lead in early and late gestation in the mouse

203Pb(NO3)2 was administered i.v. to pregnant C57BL mice at different stages, from day 8 to day 18 of gestation. The whole animals or excised uteri were subjected to autoradiography or were autopsied for scintillation counting of excised organs. Lead appeared in embryonic and fetal tissues at all stages of gestation. Early (approx. day 8-11) lead was restricted mainly to the embryonic blood, suggesting that free lead was essentially not transferred to the embryo but may have been incorporated in the embryonic hemoglobin when the erythrocytes were formed in the yolk sac placenta (an extraembryonic membrane). From day 12 and later, an uptake was seen in the liver and the cartilaginous skeleton, and from day 14, a strong accumulation was found in calcified bone. This means that the overall fetal concentration increased successively with gestational age of the conceptus. The uptake in fetal liver may be related to the erythropoiesis taking place in the liver in later gestation. While an accumulation of lead was observed in proximal tubuli of the maternal kidney, no corresponding uptake occurred in the fetal kidney. Although lead is teratogenic, causing among others skeletal defects, no effect of inorganic lead in mM concentration was seen on a chondrogenic cell system in vitro. Due to the predominance of lead in hemoglobin, a mechanism of teratogensis based on inhibition of fetal hemoglobin synthesis or function is discussed.

Placental and stillbirth tissue lead concentrations in occupationally exposed women

The lead values in maternal and infant blood, in placental tissue, and in stillbirth liver, kidney, and rib- and skull-bones have been determined in samples from the Stoke-on-Trent area. The lead values in antenatal blood and placenta increase with occupational exposure; liver and kidney stillbirth lead values are lower than those of much older children and rib-bone lead values from stillbirths were on average three times as high as those from a control group comprised of cot deaths and early infant deaths from accidental causes.

Renal insufficiency associated with excessive lead exposure

Water lead concentrations were measured in 970 households throughout Scotland. Blood lead concentrations were measured in 283 people living in houses with water lead levels of over 0-48 mumol/l (100 mug/l). A highly significant correlation was found between lead concentrations in water and blood. Raised blood lead concentrations were associated with renal insufficiency, reflected in raised serum urea concentrations, and with hyperuricaemia, although there was no evidence of clinical disease in any of the affected people. This is further evidence that excessive lead in domestic water supplies has a harmful effect on the community's health.