[Lead in drinking water-an old problem, a new EU directive]. / Blei im Trinkwasser ­ ein altes Problem, eine neue EU-Richtlinie.

BACKGROUND: Lead pipes have been used in drinking water installations for a long time. Only since 1973 have their use in new buildings been strongly discouraged; nevertheless, they are still found in old buildings. Furthermore, lead-containing alloys are still used today in components such as fittings. This results in an avoidable pollution of drinking water. The health significance of this pollution is acknowledged by a reduction of the currently valid limit value from 10 µg/l to 5 µg/l by the new EU drinking water directive passed in 2020. This directive provides for a transition period of 15 years. OBJECTIVES: The relevance of a stricter limit value for lead in drinking water will be evaluated based by the results of routine analyses, and the necessary public health measures to prevent exposure of vulnerable groups will be formulated. MATERIAL AND METHODS: A retrospective analysis of routine samples from the city of Bonn, which an accredited drinking water laboratory had examined in the years 1997-2019, was performed. RESULTS: Of the 16,060 samples analyzed, 75.36% were below the quantitative limit of quantification. The median of the quantifiable samples was above the future limit for lead in drinking water in each year considered. No effect of the last transition period of 10 years (2003-2013) could be detected. DISCUSSION: Even though no systematic studies on lead pollution in German municipalities are available, the subject is still highly topical. Lead exposure from drinking water installations is a completely avoidable health risk, but it can only be regulated by consistent enforcement of the applicable rules by the health authorities. The health authorities must be adequately equipped in terms of personnel, material, and financial resources.

[Aluminium release of glitter particles in removable orthodontic appliances]. / Freisetzung von Aluminium aus Glitzerpartikeln bei herausnehmbaren kieferorthopädischen Apparaturen.

BACKGROUND AND AIM: In order to support children's compliance with orthodontic treatment, glitter particles containing aluminium (Al) are often embedded in the acrylic of removable appliances. When worn for up to 16 h daily for 2-3 years, it can be assumed that Al ions diffuse into saliva over time. The aim of this study was to investigate the release of Al ions from the acrylic using different orthodontic wires. MATERIALS AND METHOD: Test specimens (surface area 5.65 cm2) were prepared from orthodontic resin and various wires; half contained aluminium glitter particles. The test specimens were placed in Petri dishes containing 50 ml of corrosion medium (pH 2.3) according to DIN EN ISO 10271 at 37 °C for 7 days. Inductively coupled plasma mass spectrometry (ICP-MS) was used to quantify the specific ions in the corrosion solution. RESULTS: Statistical analysis showed a significant difference in the concentration of Al ions between samples with and without glitter particles. Concentrations from samples with glitter reached up to 14,474 µg/l Al ions; samples without glitter contained on average 1260 µg/l. A small proportion of the Al ions may originate from the alloys of the wires. CONCLUSIONS: It should be investigated whether the aluminium concentration can lead to health risks for humans. In view of the findings, orthodontists should not offer appliances containing glitter in order to minimize aluminium uptake with saliva. It needs to be clarified whether the conditions found in the oral cavity lead to the same results as under the abovementioned conditions. Legislation should be developed to limit the release of aluminium from orthodontic products.

In Vitro Ion Release of Wires in Removable Orthodontic Appliances.

Various orthodontic wire compositions and configurations are present on the market for removable appliances; however, there have still been only few studies focusing on the effect of resin color and additives such as glitter on corrosion of metallic wires under different conditions. Thus, the aim of the study was to compare concentrations of released ions (aluminium, chromium, nickel) in a corrosive medium under three different conditions: non-loaded wires, loaded wires, and non-loaded wires treated with Kukis® cleaning tablets. Six different wires made of three types of steel alloy were embedded in PMMA resin leaving one centimetre of each wire emerging from the resin to come into contact with the corrosive medium. Glitter particles were added to half of the produced test specimens. For the unloaded test series, five specimens of each group were covered in a petri dish with 50 mL of corrosive medium (pH 2.3) following EN-ISO 10271 for seven days at 37 °C. The wires for the mechanically loaded test specimens overlapped the resin by 5 cm and were clamped into a time-switched electric drive for a defined period of time before the samples were taken after a testing time of 7 days. In the third group, unloaded test specimens were transferred from their petri dishes into the prepared Kukis® solution every 24 h before being stored in the corrosive medium. Inductively coupled plasma mass spectrometry (ICP-MS) was used to quantify the specific ions in the corrosive solution. Statistical analysis showed that the mechanical loading of all wires could significantly raise the diffusion of ions into the corrosive medium. The colour of the resin did not affect the concentration of the released ions. The Kukis® cleaning tabs could not lower the corrosion of the tested metals, as some of the wires were corroded even more using the brace cleanser. Glitter-containing test specimens showed significantly higher amounts of aluminium. Mechanical loading as well as the presence of glitter particles in the resin significantly affected ion concentrations.

Influence of fish on habitat choice of water birds: a whole system experiment.

It is notoriously difficult to study population interactions among highly mobile animals that cannot be meaningfully confined to experimental plots of limited size. For example, migratory water birds are believed to suffer from competition with resident fish populations for shared food resources. While observational evidence in support of this hypothesis is accumulating, replicated experiments addressing this issue at the proper spatial scale are lacking. Here, we report from a replicated whole-system experiment in which we stocked large (0.07 km2), shallow (< or =2.5 m deep), highly eutrophic ponds in the bird protection area "Ismaninger Speichersee mit Fischteichen" with different densities of carp and assessed the responses of water birds and their food resources during summer over several years. In all years, the biomasses of benthic macroinvertebrates, macroalgae, and macrophytes as well as the densities of herbivorous, carnivorous, and omnivorous water birds were reduced in carp ponds compared to fishless ponds. The negative effects of carp on food resources and on the numbers of water birds feeding in carp ponds increased over the season (May-September) and were stronger at high than at low stocking densities of carp. Consequently, differences in resource densities between ponds with and without carp increased, and the ranking of ponds with respect to resource densities became more predictable over the season. These factors may have contributed to a seasonal improvement of the birds' abilities to track resource densities across ponds, as suggested by tight correlations of bird numbers on ponds with resource densities late, but not early, in the season.