Prenatal exposure to organochlorine compounds and neonatal thyroid stimulating hormone levels.

It has been suggested that prenatal exposure to some organochlorine compounds (OCs) may adversely affect thyroid function and may, therefore, impair neurodevelopment. The main aim of this study was to examine the relationship of cord serum levels of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (4,4'-DDT), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (4,4'-DDE), ß-hexachlorocyclohexane (ß-HCH), hexachlorobenzene (HCB), four individual polychlorobiphenyl (PCB) congeners (118, 138, 153, and 180), and their sum, with neonatal thyroid stimulating hormone (TSH) levels in blood samples in a mother-infant cohort in Valencia, Spain. This study included 453 infants born between 2004 and 2006. We measured OC concentrations in umbilical cord serum and TSH in blood of newborns shortly after birth. Associations between neonatal TSH levels and prenatal OC exposure adjusted for covariates were assessed using multivariate linear regression analyses. Neonatal TSH levels tended to be higher in newborns with ß-HCH levels in umbilical cord above 90th percentile (104 ng/g lipid) than in those with levels below the median (34 ng/g lipid), with an adjusted increment in neonatal TSH levels of 21% (95% confidence interval=-3, 51; P=0.09). No statistically significant association was found between the remaining OCs and TSH at birth. Prenatal exposure to ß-HCH may affect neonatal thyroid hormone status and its function in neurological development.

[Analysis of PCB- and PCT-methylsulfones in the blood in yusho patients].

Polychlorinated biphenyl (PCB)- and terphenyl (PCT)-methylsulfones were isolated from the blood of yusho patients sampled in 1987 and characterized by gas chromatography with mass spectrometry (GC/MS), electron capture detection (GC/ECD) and flame photometric detection (GC/FPD). GC/MS analysis for PCB-methylsulfones showed that all the blood tested (nine samples) contained the tri- and tetrachloro congeners. The concentrations of PCB-methylsulfones were estimated to be 15-120 ppb. PCT-methylsulfones detected in the same fraction, which were confirmed by GC/MS comparison with authentic samples as well as by GC/ECD and GC/FPD, consisted of tetra-, penta- and hexachloroterphenyl methylsulfone congeners. The levels of PCT-methylsulfones in six samples detected were preliminarily estimated to be 10-270 ppb, on the basis of a PCB-methylsulfone standard. Their origins and biological effects are unclear at present.

Polychlorinated terphenyls as an environmental pollutant in Japan.

This paper summarizes the results of the studies made by our group and other investigators in Japan on the residue levels of polychlorinated terphenyls (PCTs) in a variety of items in the environment including the human body. In contrast to widespread distribution of PCBs in the environment, PCT residues were seldom found in samples from aquatic environments such as water and sludge and waterfowl and fish, and, if found, the levels of PCTs were so low as to be practically negligible. Similarly, no significant levels of PCTs were detectable in foodstuffs such as edible oils, vegetables, dairy products and meat and in prepared diets. These findings may be explained by the fact that PCTs are much less volatile and soluble than PCBs and the total industrial output of PCTs was as small as 2700 tonnes which is 1/20 of PCBs produced in Japan. However, the levels of PCTs in human fat and blood were shown to be almost equivalent to PCBs, despite a negligible amount of PCTs being found in food. No clear explanation of human contamination by PCTs has been proposed so far.