Results from Two Interlaboratory Comparison Tests Organized in Germany and at the EU Level for Analysis of Acrylamide in Food

After the publication of high levels of acrylamide (AA) in food, many research activities started all over the world in order to determine the occurrence and the concentration of this substance in various types of food. As no validated methods were available at that time, interlaboratory studies on the determination of AA in food were of the highest priority. Under the boundary conditions of applying well-established evaluation schemes, the results of 2 studies conducted by the Federal Institute for Risk Assessment (BfR) in Germany and by the European Commission's Directorate General Joint Research Center (JRC) exhibited an overall acceptable performance of the participants in these studies. Nevertheless, many laboratories showed problems in determining AA in food with a complex matrix such as cocoa. The results of analysis also showed a broader variation of AA for samples with low AA concentrations and indicated a bias of the results obtained by gas chromatography–mass spectrometry without derivatization. Improvements of the performance of some laboratories appeared to be necessary.

Temporal trends of PCDD, PCDF and PCB levels in muscle meat of herring from different fishing grounds of the Baltic Sea and actual data of different fish species from the Western Baltic Sea

To study the time trend of PCDD, PCDF and dl-PCB levels in the muscle of herring from the Western Baltic Sea, samples were collected in 2006 at the same fishing locations as in 1999. The results demonstrated no obvious change in contamination levels based on content in fat during the last 7 years. The site-dependent increase in WHO-PCDD/F-PCB-TEQ concentrations already found in 1999 in fishing grounds between the Skagerrak and the east of Bornholm could be confirmed by this study. In addition, an overview is given in this study on the actual WHO-TEQ concentrations in cod, eel, herring, sprat and some salmon landed at various fishing ports along the coast of Mecklenburg-Western Pomerania/Germany. All herring samples were found to be below the maximum levels and the concentrations in cod were below 1 ng WHO-TEQ kg(-1) wet weight (ww). The contaminant levels of 28 pooled eel samples varied considerably between 1.35 and 16.75 ng WHO-TEQ kg(-1) ww. The results are discussed in relation to the fat content and to the weight of the eels.

Acrylamide–occurrence in mixed concentrate feed for dairy cows and carry-over into milk

During the preparation of cooked foods acrylamide is formed from asparagine and reducing sugars at high temperatures. By-products of oil, starch and sugar production, which may be found in animal feed, partially result from processing steps using heat treatment that are similarly likely to form acrylamide. Possibly, pelletizing during the processing of mixed concentrates may also be involved in acrylamide formation. Thus the occurrence of acrylamide in animal feed and the potential for carry-over into animal products should be tested. Independently of the feed matrix, 1.5 g per day of acrylamide was fed to a cow for ten days resulting in a mean concentration of 175 microg/kg of acrylamide in the milk. From the data obtained the mean carry-over was found to be 0.24%, and a mean half-life time of 2.8 h was estimated. This means acrylamide was rapidly transformed in the cow. The acrylamide concentrations in three commercial mixed concentrates were respectively 180, 145 and 140 microg/kg feed. To test the possible effect of pelletizing, the peripheral zones were separately analysed. No difference in concentration was observed. Based on the carry-over rate estimated in this study, a maximum concentration of approx. 0.2 microg/kg of acrylamide would be expected in milk from cows fed with such feeds.

Results from two interlaboratory comparison tests organized in Germany and at the EU level for analysis of acrylamide in food

After the publication of high levels of acrylamide (AA) in food, many research activities started all over the world in order to determine the occurrence and the concentration of this substance in various types of food. As no validated methods were available at that time, interlaboratory studies on the determination of AA in food were of the highest priority. Under the boundary conditions of applying well-established evaluation schemes, the results of 2 studies conducted by the Federal Institute for Risk Assessment (BfR) in Germany and by the European Commission's Directorate General Joint Research Center (JRC) exhibited an overall acceptable performance of the participants in these studies. Nevertheless, many laboratories showed problems in determining AA in food with a complex matrix such as cocoa. The results of analysis also showed a broader variation of AA for samples with low AA concentrations and indicated a bias of the results obtained by gas chromatography-mass spectrometry without derivatization. Improvements of the performance of some laboratories appeared to be necessary.

Effect of low dose mono-ortho 2,3',4,4',5 pentachlorobiphenyl on thyroid hormone status and EROD activity in rat offspring: consequences for risk assessment

Toxic equivalency factor (TEF) has been proposed to estimate the risk of polychlorinated biphenyl (PCB) congeners. However, ortho chlorine substitution in the two phenyl rings gives each PCB its own pattern of toxicity which is different from the mechanism of action of 2,3,7,8-tetrachlorodibenzo-p-dioxin. The present study evaluated the effect of prenatal and postnatal exposure to a low dose of the mono-ortho pentachlorobiphenyl PCB 118 on thyroid hormone concentrations and EROD activity in rats. Moreover, the tissue distribution of PCB 118 following one oral dose was evaluated. Sprague-Dawley rats were treated by gavage on GD 6 with 375 microg of PCB 118/kg b.w. Decreases in thyroxine and TSH levels were observed in dams at the end of lactation. Perinatal exposure to a low dose of PCB 118 permanently disrupted the hypothalamo-pituitary-thyroid (HPT) axis leading to a significant increase in thyroxine levels in offspring, as a 'thyroid resistance syndrome'. It is noteworthy that no changes in hepatic EROD activity were detected in dams at the end of lactation, even in the presence of high amounts of PCB in liver. Based on hepatic EROD activity (as a biomarker for aryl hydrocarbon receptor (AhR) induction), the mechanism of thyroid homeostasis disruption seems to be AhR-independent. Additionally, the 'thyroid resistance syndrome' observed in our study indicates the need for further detailed investigations on the HPT axis. We conclude that not only TEF, but also AhR-independent responses should be taken into account for risk assessment of mono-ortho PCB congeners.

PCDDs, PCDFs, PCBs, and other organochlorine compounds in human milk from Rio de Janeiro, Brazil

The levels of polychlorinated dibenzo-p-dioxins (PCDDs) and -furans (PCDFs), polychlorinated biphenyls (PCBs), and other organochlorine compounds were determined in a pooled sample of breast milk from 40 mothers (first lactation: 33; second lactation: 7, age: 15-38 years) living in the urban area of Rio de Janeiro County, Brazil, in 1992. Mothers were breastfeeding only one infant and milk was collected between 4 and 6 weeks after delivery. The results showed a dioxin equivalent concentration of 8.1 pg I-TEq/g milk fat. The levels of other chlorinated compounds (micrograms per gram of milk fat) were as follows: PCBs (total), 0.15; alpha-HCH, 0.001; beta-HCH, 0.27;gamma-HCH, 0.005; HCB, 0.012; DDT (total), 1.7; dieldrin, 0.023, and cis-heptachlor epoxide, 0.008. These results suggest that human background contamination by PCDD/Fs, PCBs, and HCB in Rio de Janeiro is lower than that generally found in industrialized countries.

Custom-made cast titanium implants produced with CAD/CAM for the reconstruction of cranium defects

Titanium implants for the reconstruction of bony skull defects, using data from three-dimensional spiral computer tomography, have been described by other authors. Instead of milling the implants from a titanium block, an advanced method of rapid prototyping for a fine casting process is presented. Casting vs milling offers several advantages. It is possible to form very thinly tapered structures and to obtain more complex geometrical structures with smaller diameters. Many geometrical forms, which cannot be milled for technical reasons, can be produced using this technique.

Reproductive toxicity and tissue concentrations of 3,3',4,4'-tetrachlorobiphenyl (PCB 77) in male adult rats

1 The aim of this study was to ascertain the reproductive effects of PCB 77 on adult male rats and to determine its concentration in the liver and testis. Adult male rats (n = 15/group) were treated subcutaneously with a single dose of 18 mg/kg bw (PC18) or with 60 mg/kg bw (PC60). The substance was dissolved in a 10 ml volume of peanut oil/kg. Control rats received the same volume of the vehicle. The reproductive effects as well as the concentration of PCB 77 in the liver and testis were investigated 1, 4 and 8 weeks after treatment. 2 In both groups, the daily sperm production (DSP; x10(6)) remained permanently reduced in the PC18 as well as in the PC60 groups throughout the entire investigation period (DSP week 8: control: 31 +/- 7; PC18: 22 +/- 5; PC60: 20 +/- 7). The sperm number (x10(6)) per cauda epididymis was affected only at the 1st and 4th week after treatment (control week 1: 211 +/- 67; PC18 week 1: 135 +/- 62; PC60 week 1: 142 +/- 49). Moreover, a significant increase in the percentage of abnormal sperm was observed 4 weeks following treatment in the PC18 and PC60 groups and 8 weeks after treatment in the PC60 group. Abnormal tails were the most frequent changes observed. 3 The relative testicular and prostata weights (g) were slightly increased in the PC60 group at the 1st and 4th week following treatment (testis weight: control/I: 0.46 +/- 0.02; PC60/I: 0.51 +/- 0.03). 4 The serum testosterone concentrations and effects on testis morphology were not reported. 5 The maximum concentration of PCB 77 was detected in the liver and testis 1 week after treatment. The concentration declined 4 weeks after treatment in both organs, but still a significant amount of PCB 77 was detectable in the liver as well as in the testis 8 weeks after treatment. 6 The results demonstrate that PCB 77 affects sperm variables when applied to adult rats and that the elimination of PCB 77 in the testis parallels that of the liver.

Tissue distribution, toxicokinetics and induction of hepatic drug metabolizing enzymes in male rats after a single s.c. dose of 3,4,3',4'-tetrachlorobiphenyl (PCB-77)

The tissue distribution and toxicokinetics of PCB-77 after a single s.c. dose of 6 mg/kg body weight was investigated in male adult rats as well as the concurrent induction of hepatic drug-metabolizing enzymes. During five days after treatment, the PCB-77 concentrations on fat weight basis in testis and in whole blood were found to be about in the same range as the concentrations in adipose tissue, whereas in liver fat PCB-77 accumulated. EROD and MROD activities were induced by about 8 and 4 times, respectively, during a period of two weeks after treatment. Concentrations in adipose tissue and in liver as well as the hepatic enzyme activities rapidly declined during the investigation period of eight weeks. An elimination half-life for PCB-77 of approximately 7-9 days was estimated.

PCDD and PCDF exposure and levels in humans in Germany

For nonoccupationally exposed persons, the daily intake via food consumption has been calculated to be 0.35 pg/kg body weight per day for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 2.3 pg/kg body weight per day for TCDD equivalents (TEqs). As compared to food, other sources and pathways are of minor importance. Food of animal origin contributes most, although human exposure begins with atmospheric emissions depositing these compounds on plant surfaces. In the meantime, a possible additional body burden from cardboard containers for cow's milk and coffee filters has been practically excluded. Of the 210 existing PCDDs and PCDFs, only 15 2,3,7,8-substituted isomers with a characteristic congener pattern can be found in samples of human origin. In adipose tissue and milk samples, mean levels for 2,3,7,8-TCDD of 7.2 and 3.6 pg/g fat, respectively, and of 56 (range 18-122) and 30 (range 10-72) pg TEqs/g fat, respectively, were determined. Human data revealed a dependency of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/PCDF) levels on age. In human milk, levels became reduced with the number of children born to mothers and duration of breast-feeding period. The average daily intake for a breast-fed child has been calculated to be 17 pg 2,3,7,8-TCDD/kg body weight per day and 142 pg TEqs/kg body weight per day, respectively. Levels in adipose tissue of infants, even if breast fed, were distinctly lower compared to human milk. In human milk, adipose tissue, and whole blood, PCDD/PCDF concentrations have been found to be equal on a fat-weight basis. Liver fat accumulated PCDD/PCDF with an alteration in the congener distribution pattern, whereas brain, even on a fat-weight basis, showed the lowest concentrations. Elevated or even high levels were found in occupationally exposed persons working in special chemical plants or involved in specific processes. There are limited data suggesting slightly elevated PCDD/PCDF levels are due to long-term consumption of a large share of food produced near point sources with a heavy emission or ingestion of soil or dust from such areas.

Isomer-specific determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin and related compounds in human fat and food

An analytical procedure for the isomer-specific quantification of polychlorinated dibenzo-p-dioxins and dibenzofurans in samples of human and animal origin is described. It consists of a large-scale clean-up including various kinds of column chromatography and high-resolution gas chromatographic/mass spectrometric quantification referring to internal 13C-labelled standards. By additional application of gel-permeation chromatography and the use of a retention gap, detection limits in the low ppq range (10(-15) were achieved.