Chemical stabilization of polymers: Implications for dermal exposure to additives.

Technical benefits of additives in polymers stand in marked contrast to their associated health risks. Here, a multi-analyte method based on gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) was developed to quantify polymer additives in complex matrices such as low-density polyethylene (LDPE) and isolated human skin layers after dermal exposure ex vivo. That way both technical aspects and dermal exposure were investigated. The effects of polymer additivation on the material were studied using the example of LDPE. To this end, a tailor-made polymer was applied in aging studies that had been furnished with two different mixtures of phenol- and diarylamine-based antioxidants, plasticizers and processing aids. Upon accelerated thermo-oxidative aging of the material, the formation of LDPE degradation products was monitored with attenuated total reflectance-Fourier transformed infrared (ATR-FTIR) spectroscopy. Compared to pure LDPE, a protective effect of added antioxidants could be observed on the integrity of the polymer. Further, thermo-oxidative degradation of the additives and its kinetics were investigated using LDPE or squalane as matrix. The half-lives of additives in both matrices revealed significant differences between the tested additives as well as between LDPE and squalane. For instance, 2-tert-butyl-6-[(3-tert-butyl-2-hydroxy-5-methylphenyl)methyl]-4-methylphenol (Antioxidant 2246) showed a half-life 12 times lower when incorporated in LDPE as compared to squalane. As a model for dermal exposure of consumers, human skin was brought into contact with the tailor-made LDPE containing additives ex vivo in static Franz diffusion cells. The skin was then analyzed for additives and decomposition products. This study proved 10 polymer additives of diverse pysicochemical properties and functionalities to migrate out of the polymer and eventually overcome the intact human skin barrier during contact. Moreover, their individual distribution within distinct skin layers was demonstrated. This is exemplified by the penetration of the procarcinogenic antioxidant N-phenylnaphthalen-2-amine (Neozon D) into the viable epidermis and the permeation through the skin of the neurotoxic plasticizer N-butylbenzenesulfonamide (NBBS). In addition, the analyses of additive degradation products in the isolated skin layers revealed the presence of 2-tert-butyl-4-methylphenol in all layers after contact to a polymer with substances of origin like Antioxidant 2246. Thus, attention needs to be paid to absorption of polymer additives together with their degradation products when it comes to dermal exposure assessment.

Skin permeation of polycyclic aromatic hydrocarbons: A solvent-based in vitro approach to assess dermal exposures against benzo[a]pyrene and dibenzopyrenes.

Consumer products with high contents of polycyclic aromatic hydrocarbons (PAHs) were repeatedly identified by market surveillance authorities. Since several of the individual compounds have been identified as genotoxic carcinogens, there might be health risks associated with the usage of these items. It therefore becomes reasonable to argue to reduce PAH contents in consumer products to a level as low as possible. This study presents data on the migration of PAHs from consumer products into aqueous sweat simulant or aqueous ethanol and on its combined migration and penetration into human skin. Product specimens were either submerged in simulant, or placed directly on test skins in Franz cell chambers to simulate dermal contacts. Migration of hexacyclic dibenzopyrenes became detectable by using ethanolic simulant, but not in aqueous sweat simulant. Similarly, migration of the pentacyclic model carcinogen benzo[a]pyrene (B[a]P) into aqueous sweat simulant was significantly lower when compared with human skin or skin models. The results point to a gross underestimation (about two orders of magnitude) when using aqueous sweat simulant instead of human skin for assessing PAH migration. On the other side, the usage of 20% ethanol as simulant revealed good agreement to the actual exposure of human skin against B[a]P migrating out of contaminated products. Our results underline that aqueous sweat simulant is not suitable to study dermal migration of highly lipophilic compounds.

Flow cytometric analysis of platelet membrane antigens during and after continuous-flow plateletpheresis.

BACKGROUND: The influence, extent, and duration of changes in platelet antigen expression caused by blood-biomaterial interaction in plateletpheresis were assessed. STUDY DESIGN AND METHODS: Twenty-two apheresis donors were studied by using two automated continuous-flow apheresis devices. Blood samples were taken before, during, and for 4 days after extracorporeal circulation. The platelet surface expression of glycoproteins CD41a, CD42b, CD62p, and CD63 was analyzed by flow cytometry. RESULTS: Over the course of plateletpheresis, there was a significant increase in mean channel fluorescence intensity (MCFI) of CD62p, from 25.1 +/- 7.9 (mean +/- SD) to 50.4 +/- 28.9, and of CD63, from 22.3 +/- 6.5 to 33.3 +/- 13.2. There was a significant decrease in CD41a expression as measured by the MCFI, from 1129.8 +/- 125.0 to 1066.6 +/- 102.2, and in CD42b MCFI, from 329.6 +/- 49.4 to 321.4 +/- 52.0. The two apheresis devices showed different platelet activation kinetics, but the overall MCFI of CD62p and CD63 did not significantly diverge after 60 minutes of apheresis. CD62p and CD63 expression as measured by the MCFI returned to preapheresis levels during the follow-up period in 25 and 25 of 44 procedures, respectively, within 24 hours; in 10 and 13 of 44 procedures after 48 hours; in 7 and 3 of 44 procedures after 72 hours; and in 2 and 3 of 44 procedures on Day 5. CONCLUSION: The varying kinetics of expression, as measured by the MCFI, of platelet antigens CD62p, CD63, CD41a, and CD42b during extracorporeal circulation may be useful for biocompatibility testing. Activated platelets continue to circulate in donors for several days after cytapheresis, which suggests that a sufficient interval between apheresis procedures is necessary to avoid the collection of activated platelets.

[Uncovered bones on the Baltic Sea beach--human or animal?]. / Knochenfund am Ostseestrand--Mensch oder Tier?

Report of an unusual finding of bones on the shore of the Baltic Sea. Although the morphological findings appeared similar to a human foot skeleton, a quick identification as sea dog bone was possible.

[Prevalence of alcohol in fatalities in forensic medicine]. / Zur Alkoholprävalenz bei Todesfällen in der Rechtsmedizin.

Blood alcohol tests were carried out at the Institute of Forensic Medicine of the University of Hamburg in 1,000 sudden unexpected natural deaths and non-natural deaths (590 males, 410 females) during the first six months of 1989. In 18.6% of the cases (142 males, 44 females) a blood alcohol concentration of more than 0.1% was found. The blood alcohol concentration ranged from 0.1 to 1% in 87 cases; in 99 cases the blood alcohol concentration exceeded 1%; there were 17 fatalities with more than 3%. More than 95% of blood alcohol concentration values exceeding 2.5% were found in the age group of 40-69 years. As expected positive blood alcohol estimations and especially high blood alcohol concentrations were found in non-natural deaths. However, many cases with relevant blood alcohol findings had been classified as "sudden natural death" and were not investigated by autopsy. In 74 cases alcohol blood tests were ordered by the police.

[Prevalence of hepatitis B in fatalities in forensic medicine]. / Zur Hepatitis-B-Prävalenz bei Todesfällen in der Rechtsmedizin.

Serological screening investigations for hepatitis B were carried out on 1000 sudden and unexpected fatalities from natural causes and non-natural deaths at the Institute for Forensic Medicine in Hamburg. The results were compared with the serological tests of the drug deaths from 1983-1989 and the HIV-infected bodies from 1984-1989. It was found that anti-HBc was positive in 19.2% of the unselected cases as compared with 46.1% in drug related deaths and 73% in the HIV-infected group. HBsAg as a marker that expresses infectiosity was present in 15 cases (1.5%) of 1000 unselected cases, 4.4% of the drug related deaths and 15.8% of the HIV-infected group.