The association between prenatal exposure to organochlorine pesticides and thyroid hormone levels in newborns in Yancheng, China.

Organochlorine pesticides can interfere with the thyroid hormones that play an important role in early neurodevelopment. Although organochlorine pesticides have been banned in China since 1983, their residues are still detectable in the environment. However, few studies have investigated the adverse health effects of prenatal exposure to organochlorine pesticide residues on newborns in China. The present study, conducted in Yancheng City, Jiangsu Province, China, aimed to examine the association between the levels of organochlorine pesticides in maternal and cord sera and to assess the impact of prenatal exposure to organochlorine pesticides on thyroid hormone levels in cord serum. Eleven organochlorine pesticides in maternal and cord sera were measured in 247 mother-infant pairs recruited from Yancheng City between February 2010 and June 2010. The concentration of the thyroid hormones free triiodothyronine (FT3), free thyroxine (FT4), and thyrotropin (TSH) were determined in cord serum. Among the 11 tested organochlorine pesticides, the detectable levels of hexachlorobenzene (HCB), ß-hexachlorocycolohexane (ß-HCH) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) in both maternal and cord sera were above 50%. The levels of ß-HCH and p,p'-DDE in maternal sera were positively associated with the levels in cord sera (r=0.421, P<0.01; r=0.288, P<0.01). After adjusting for confounders, the TSH level in cord serum samples was negatively associated with the HCB level (OR=0.535, 95% CI=(0.304-0.941)). Our data demonstrated that DDT, ß-HCH and HCB residues bioconcentrate in maternal and cord sera. Moreover, the correlation analysis suggested that organochlorine pesticides in maternal blood can transfer through the placenta and affect newborn thyroid hormone levels.

[Low-temperature preparation of TiO2/PS/Fe3O4, and its photocatalytic activity and magnetic recovery].

This study reports the fabrication of magnetically responsive titania catalyst, which consisted of a magnetic core surrounded by a titania shell. The magnetic core (oleic acid-modified Fe3O4 nanoparticles) was modified with polystyrene as inert isolating layer. The magnetic photocatalyst was prepared at low temperature (90 degrees C) and a neutral pH (about 7). The phase composition, morphology, surface properties and magnetic properties of the composite particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier infrared photometer (FT-IR) and vibrating sample magnetometer (VSM). The photocatalytic activity of the samples were determined by degradation of phenol and their recovery characteristics were determined by a self-regulating magnetic recycling equipment. The results illustrated that the mean diameter of anatase titanium dioxide synthesized at low temperature was 2-5 nm, the catalyst TiO2/PS/Fe3O4 [the molar ratio of the magnetic photocatalyst was n(TiO2): n(St): n(Fe3O4) = 60:2.5:1] had the structural integrity of shell/shell/core, and titanium dioxide was loaded firmly on the PS/FeO4 surface. The photocatalytic degradation of phenol followed first-order reaction kinetics and the reaction rate constant K of the TiO2/PS/Fe3O4 [n(TiO2): n(St): n (Fe3O4) = 60:2.5:1] was 0.0258, which was close to that of pure TiO2 (K = 0.0262). After 5 times recycling, the K value reduced only by 0.0034. The catalyst had a strong magnetic induction, and the average recovery rate reached 92%. The magnetic TiO2 photocatalyst prepared by this low-temperature hydrolysis method has a good application prospect.