The bioaccumulation and fate of a branched 14C-p-nonylphenol isomer in Lymnaea stagnalis L

A single branched isomer of p-nonylphenol, 4(3',6'-dimethyl-3'-heptyl)-phenol, previously identified by gas chromatography-mass spectrometry as one of the major constituent isomers in p-nonylphenol (constituting approximately 10% of all its isomers), was synthesized and used in studies of its bioaccumulation and excretion in the hermophroditic pond snail Lymnaea stagnalis L. Branched isomers of nonylphenol are perceived to have more estrogenlike toxicity than the straight-chain isomers in addition to being more resistant to biodegradation in the environment. With an average static exposure concentration of 104 microg/L (range: 92-116 microg/L) in water at 19 degrees C for 8 d, the uptake of the compound was found to be fairly rapid, reaching a peak concentration of 23,548 microg/kg of whole tissue wet weight after 5 d and a peak bioaccumulation factor (BAFw) of 242 (5,562, based on lipid weight) after 3 d. The uptake data fitted into a logarithmic expression C(t) = 5,231 ln(t) + 11,956, where C(t) is the amount of residues accumulated in whole tissue in micrograms per kilogram tissue wet weight after a period of time, t, and t is the period of exposure in days. By determination of the excretion of 14C-residues released in water and in feces, an average loss of 96% of the accumulated residues was achieved after 22 d of continuous exposure to clean water. By first-order kinetics analysis of the excretion data, an average half-life of excretion of 4.9 d was obtained. By high-performance liquid chromatography and gas-liquid chromatography-mass spectrometry, a catechol metabolite, 4(3',6'-dimethyl-3'-heptyl)-catechol, was detected in tissue extracts (after hydrolysis with beta-glucuronidase) and in feces, in addition to the parent isomer, suggesting that the isomer may have been metabolized by glucuronic acid conjugation and hydroxylation at the ortho position of its phenolic ring.     

Controlled release experiments with nonylphenol in aquatic microcosms

A method of controlled release of technical nonylphenol (tNP) was developed to simulate realistic exposure in ecotoxicological studies on aquatic organisms. The direct addition of tNP from an aqueous stock solution into 50 ml of water led to a concentration decrease of 80 to 90% weight/volume (w/v) from nominal values within 48 h. The inclusion of tNP in semipermeable low-density polyethylene (LDPE) lay-flat tubing (controlled-release devices [CRDs]) of different length allowed a continuous release into pure water at a rate of about 30 microg/cm2/d. Using CRDs in aquaria containing 15 L of 63-microm-filtered lake water, eight different concentrations with maxima between 38.1 and 326.7 microg/L were maintained for 11 d. During a second experiment in 15-L aquaria, five replicates of three concentrations were maintained using CRDs of the same length. Concentrations after 38 d varied between 0.1 and 6.7, 26.1 and 41.9, and 49.9 and 76.0 microg/L. In aquatic microcosms containing 230 L of lake water, a natural plankton community, 50 L of sediment, and macrophytes, seven different tNP concentrations (maxima 11-120.1 microg/L) were maintained over 45 d using CRDs of different length. They were replaced after 14 and 25 d because release of tNP was slower than predicted from laboratory experiments. Concentrations in the top 1-cm sediment layer were on average 19 times higher during the dosing period than concentrations in the water at the same time. In the sediments, different levels of applications led to concentrations that differed less distinctly than in the water. This method is suitable for exposing aquatic organisms continuously to constant, ecologically relevant concentrations of NP and represents an improvement over previous dosing methods in which exposure varied.     

Gene expression in the liver of Long-Evans cinnamon rats during the development of hepatitis

The Long-Evans cinnamon (LEC) rat, an authentic model for Wilson disease, is characterized by a mutation in the Atp7b gene leading to a defective copper excretion and, as a consequence, to an accumulation of the metal in the liver and copper-associated hepatotoxicity. In the present communication expression profiles of genes in the liver from wild-type Long-Evans agouti (LEA) and LEC rats at different stages of copper accumulation and liver disease were investigated. Disease states were defined according to serum aspartate aminotransferase activity and bilirubin levels in serum and from histopathology of the liver. Gene expression was determined with the Affymetrix RTU34 oligonucleotide array covering 1031 genes. Compared to the LEA rat, the nondiseased LEC rat with already increased hepatic copper level showed an enhanced expression of genes, particularly related to oxidative stress and DNA damage. During the progression of the liver disease, in particular genes related to oxidative stress, DNA damage, apoptosis and inflammation with acute-phase reaction were upregulated.Electronic Supplementary Material Supplementary material is available in the online version of this article at     

Temporal changes in blood lead levels of children in east Germany

This analysis investigates the temporal changes in blood lead levels (BLL) in repeated cross-sectional surveys of 5-7 year old children conducted in 1992-93, 1995-96 and 1998-99 and in a prospective cohort from a smelter town and an agricultural control region in east Germany. The region of Hettstedt has a long history of mining and smelting resulting in high levels of heavy metal pollution whereas the region of Zerbst has no known industrial sources of heavy metals. In the region of Hettstedt lead content in ambient dust fall declined since the early 1990s due to the closure of many factories, whilst in Zerbst lead in ambient dust fall was constantly low in the 1990s. Blood lead levels decreased during the observation period both in children from the smelter town and in children from the agricultural control region. From 1992-93 to 1998-99 the mean BLLs of school entrants fell by 20% (41.6 to 33.3 micrograms/l) in Hettstedt and by 30% (34.2 to 23.8 micrograms/l) in Zerbst. In the same observation period mean BLLs of cohort children declined by 35% (41.9 to 27.3 micrograms/l) in Hettstedt and by 39% (32.3 to 19.8 micrograms/l) in Zerbst. At the beginning of the observation period cohort children were 5-7 years of age and were followed up to the age of 11-14. Adjustment for sociodemographic factors, city area and environmental uptake of lead did not influence the percentage changes in BLL of school-entrants. It seems that the decline in ambient lead fall had an impact on the body burden of lead, but the overall decrease in BLL in these two regions is caused by the overall decrease of lead in gasoline and thus in food.     

Levels of Toxic Metals in Multisectoral Samples from Winam Gulf of Lake Victoria

In this study, the distribution and sources of inputs of trace metals including Cd, Cu, Zn and Pb from various sources as well as Fe which is widely used in the construction industry, into Winam Gulf of Lake Victoria were investigated. The sampling sites were located up streams and down streams of four rivers (Sio, Nyamasaria, Nyando and Sondu-Miriu), in four beaches along the lake (Port Victoria, Kisumu Car Wash, Dunga and Hippo point beaches) and in three estates (Nyamasaria, Migosi and Nyawita) in Kisumu city, covering potential agrochemical and industrial sources and drinking water points, respectively. The concentrations (in μg/L) of trace metals analysed in the lake and river waters ranged from <1.79 (Cd), <3.83 (Pb), <1.53–3.86 (Cu), 4.37–11.6 (Zn), 11.8–2,440 (Fe). The sediment concentrations (in μg/kg × 10³) ranged from 0.19 to 1.91 (Cd), 6.86–138 (Pb), 18–100 (Cu), 36.2–443 (Zn) and 960–73,200 (Fe), with highest concentrations of all metals being recorded at Kisumu Car Wash area. The study confirmed that the concentrations of the metals accumulate downstream in the rivers both in water and sediment and these rivers are major sources of the heavy metal load into Winam Gulf of Lake Victoria.