Volatile organic compounds from building products-Results from six round robin tests with emission test chambers conducted between 2008 and 2018.

Emission testing of volatile organic compounds (VOC) from materials and products is commonly based on emission test chamber measurements. To ensure the comparability of results from different testing laboratories, their measurement performance must be verified. For this purpose, Bundesanstalt für Materialforschung und -prüfung (BAM) organizes an international proficiency test (round robin test, RRT) every two years using well-characterized test materials (one sealant, one furniture board, and four times a lacquer) with defined VOC emissions. The materials fulfilled the requirements of homogeneity, reproducibility, and stability. Altogether, 36 VOCs were included of which 33 gave test chamber air concentrations between 13 and 83 µg/m3 . This is the typical concentration range to be expected and to be quantified when performing chamber tests. Three compounds had higher concentrations between 326 and 1105 µg/m3 . In this paper, the relative standard deviations (RSD) of BAM round robin tests since 2008 are compared and the improvement of the comparability of the emission chamber testing is shown by the decrease of the mean RSD down to 28% in 2018. In contrast, the first large European interlaboratory comparison in 1999 showed a mean RSD of 51%.

Natural Building Materials for Interior Fitting and Refurbishment-What about Indoor Emissions?

Indoor air quality can be adversely affected by emissions from building materials, consequently having a negative impact on human health and well-being. In this study, more than 30 natural building materials (earth dry boards and plasters, bio-based insulation materials, and boards made of wood, flax, reed, straw, etc.) used for interior works were investigated as to their emissions of (semi-)volatile organic compounds ((S)VOC), formaldehyde, and radon. The study focused on the emissions from complete wall build-ups as they can be used for internal partition walls and the internal insulation of external walls. Test chambers were designed, allowing the compounds to release only from the surface of the material facing indoors under testing parameters that were chosen to simulate model room conditions. The emission test results were evaluated using the AgBB evaluation scheme, a procedure for the health-related evaluation of construction products and currently applied for the approval of specific groups of building materials in Germany. Seventeen out of 19 sample build-ups tested in this study would have passed this scheme since they generally proved to be low-emitting and although the combined emissions of multiple materials were tested, 50% of the measurements could be terminated before half of the total testing time.

Robustness validation of a test procedure for the determination of the radon-222 exhalation rate from construction products in VOC emission test chambers.

This study investigated the adaptation of the state-of-the-art test procedure for the determination of emissions of volatile organic compounds (VOC) from materials into indoor air to test for the radon exhalation from stony construction products. A complete robustness validation including all relevant parameters showed that the procedure can be well applied by testing institutes already holding available the required VOC testing infrastructure that solely needs to be complemented by calibrated commercial radon measurement instrumentation. When measurements of the radon exhalation from construction materials become mandatory by law, test capacity can easily be applied. This work can serve as a recommendation for the European standardisation that still is on hold in this point.

Determination of recovery rates of adsorbents for sampling very volatile organic compounds (C1C6) in dry and humid air in the sub-ppb range by use of thermal desorption gas chromatography-mass spectrometry.

The reliable measurement of very volatile organic compounds (VVOC) in indoor air by use of thermal desorption gas chromatography (TD-GC) in order to include them into evaluation schemes for building products even nowadays is a great challenge. For capturing these small molecules with carbon numbers ranging from C1C6, strong adsorbents are needed. In the present study, recovery rates of nine suitable adsorbents of the groups of porous polymers, graphitised carbon blacks (GCB) and carbon molecular sieves (CMS) are tested against a complex test gas standard containing 29 VVOC. By consideration of the recovery and the relative humidity (50% RH), combinations of the GCB Carbograph 5TD, the two CMS Carboxen 1003 and Carbosieve SII as well as the porous polymer Tenax® GR were identified to be potentially suitable for sampling the majority of the VVOC out of the gas mix. The results reveal a better performance of the adsorbents in combination than being used alone, particularly under humid sampling conditions. The recovery rates of the chosen compounds on each adsorbent should be in the range of 80-120%.

Development of a multi-VOC reference material for quality assurance in materials emission testing.

Emission test chamber measurement is necessary to proof building materials as sources of volatile organic compounds (VOCs). The results of such measurements are used to evaluate materials and label them according to their potential to emit harmful substances, polluting indoor air. If only labelled materials were installed indoors, this would improve indoor air quality and prevent negative impacts on human health. Because of the complex testing procedure, reference materials for the quality assurance are mandatory. Currently, there is a lack of such materials because most building products show a broad variation of emissions even within one batch. A previous study indicates lacquers, mixed with volatile organic pollutants, as reproducible emission source for a wide range of substances. In the present study, the curing of the lacquer-VOC mixture inside micro-chambers was optimised. Therefore, the humidity and the chamber flow were varied. Typical indoor air pollutants with a wide range of volatilities, for example, styrene, n-hexadecane, dimethyl and dibutyl phthalate were selected. It turned out that, under optimised curing parameters inside the micro-chamber, their emission can be reproduced with variations of less than 10 %. With this, a next important step towards a reference material for emission testing was achieved.

Investigations on the emissions of biocides and PCBs under low volume conditions.

The aim of this study was the development of a low volume air sampling strategy for biocides and polychlorinated biphenyls (PCB) at low air change rates in modern, air-tight showcases as they are present in museums. Lindane, pentachlorophenol, dichlofluanid, tolyfluanid, isodrin, p,p-dichlorodiphenyl trichloroethane and permethrin were the biocides and PCB28 and PCB153 were the PCBs studied, all of which are semi volatile organic compounds (SVOC). Their occurrences in the museum environment originate from various sources e.g. preventive treatment of organic exhibits or organic building materials. Exhibits are long-term exposed to these pollutants due to storing in showcases or other storage equipment at low air change rates. To achieve air sampling under the aforementioned conditions the influences of temperature, air circulation, air change rate and relative humidity on the emission behavior of the selected biocides and PCBs had to be determined. This was carried out with pre-soaked wood samples in low volume air sampling experiments using 27L test showcases and 23L and 24L emission test chambers and also diffusive sampling with glass as the sampling material.

Adaptive evolution of Toll-like receptor 5 in domesticated mammals.

BACKGROUND: Previous studies have proposed that mammalian toll like receptors (TLRs) have evolved under diversifying selection due to their role in pathogen detection. To determine if this is the case, we examined the extent of adaptive evolution in the TLR5 gene in both individual species and defined clades of the mammalia. RESULTS: In support of previous studies, we find evidence of adaptive evolution of mammalian TLR5. However, we also show that TLR5 genes of domestic livestock have a concentration of single nucleotide polymorphisms suggesting a specific signature of adaptation. Using codon models of evolution we have identified a concentration of rapidly evolving codons within the TLR5 extracellular domain a site of interaction between host and the bacterial surface protein flagellin. CONCLUSIONS: The results suggest that interactions between pathogen and host may be driving adaptive change in TLR5 by competition between species. In support of this, we have identified single nucleotide polymorphisms (SNP) in sheep and cattle TLR5 genes that are co-localised and co-incident with the predicted adaptive codons suggesting that adaptation in this region of the TLR5 gene is on-going in domestic species.

Genes controlling vaccine responses and disease resistance to respiratory viral pathogens in cattle.

Farm animals remain at risk of endemic, exotic and newly emerging viruses. Vaccination is often promoted as the best possible solution, and yet for many pathogens, either there are no appropriate vaccines or those that are available are far from ideal. A complementary approach to disease control may be to identify genes and chromosomal regions that underlie genetic variation in disease resistance and response to vaccination. However, identification of the causal polymorphisms is not straightforward as it generally requires large numbers of animals with linked phenotypes and genotypes. Investigation of genes underlying complex traits such as resistance or response to viral pathogens requires several genetic approaches including candidate genes deduced from knowledge about the cellular pathways leading to protection or pathology, or unbiased whole genome scans using markers spread across the genome. Evidence for host genetic variation exists for a number of viral diseases in cattle including bovine respiratory disease and anecdotally, foot and mouth disease virus (FMDV). We immunised and vaccinated a cattle cross herd with a 40-mer peptide derived from FMDV and a vaccine against bovine respiratory syncytial virus (BRSV). Genetic variation has been quantified. A candidate gene approach has grouped high and low antibody and T cell responders by common motifs in the peptide binding pockets of the bovine major histocompatibility complex (BoLA) DRB3 gene. This suggests that vaccines with a minimal number of epitopes that are recognised by most cattle could be designed. Whole genome scans using microsatellite and single nucleotide polymorphism (SNP) markers has revealed many novel quantitative trait loci (QTL) and SNP markers controlling both humoral and cell-mediated immunity, some of which are in genes of known immunological relevance including the toll-like receptors (TLRs). The sequencing, assembly and annotation of livestock genomes and is continuing apace. In addition, provision of high-density SNP chips should make it possible to link phenotypes with genotypes in field populations without the need for structured populations or pedigree information. This will hopefully enable fine mapping of QTL and ultimate identification of the causal gene(s). The research could lead to selection of animals that are more resistant to disease and new ways to improve vaccine efficacy.

XRF-analysis of fine and ultrafine particles emitted from laser printing devices.

In this work, the elemental composition of fine and ultrafine particles emitted by ten different laser printing devices (LPD) is examined. The particle number concentration time series was measured as well as the particle size distributions. In parallel, emitted particles were size-selectively sampled with a cascade impactor and subsequently analyzed by the means of XRF. In order to identify potential sources for the aerosol's elemental composition, materials involved in the printing process such as toner, paper, and structural components of the printer were also analyzed. While the majority of particle emissions from laser printers are known to consist of recondensated semi volatile organic compounds, elemental analysis identifies Si, S, Cl, Ca, Ti, Cr, and Fe as well as traces of Ni and Zn in different size fractions of the aerosols. These elements can mainly be assigned to contributions from toner and paper. The detection of elements that are likely to be present in inorganic compounds is in good agreement with the measurement of nonvolatile particles. Quantitative measurements of solid particles at 400 °C resulted in residues of 1.6 × 10(9) and 1.5 × 10(10) particles per print job, representing fractions of 0.2% and 1.9% of the total number of emitted particles at room temperature. In combination with the XRF results it is concluded that solid inorganic particles contribute to LPD emissions in measurable quantities. Furthermore, for the first time Br was detected in significant concentrations in the aerosol emitted from two LPD. The analysis of several possible sources identified the plastic housings of the fuser units as main sources due to substantial Br concentrations related to brominated flame retardants.

Comparative genomics of Toll-like receptor signalling in five species.

BACKGROUND: Over the last decade, several studies have identified quantitative trait loci (QTL) affecting variation of immune related traits in mammals. Recent studies in humans and mice suggest that part of this variation may be caused by polymorphisms in genes involved in Toll-like receptor (TLR) signalling. In this project, we used a comparative approach to investigate the importance of TLR-related genes in comparison with other immunologically relevant genes for resistance traits in five species by associating their genomic location with previously published immune-related QTL regions. RESULTS: We report the genomic localisation of TLR1-10 and ten associated signalling molecules in sheep and pig using in-silico and/or radiation hybrid (RH) mapping techniques and compare their positions with their annotated homologues in the human, cattle and mouse whole genome sequences. We also report medium-density RH maps for porcine chromosomes 8 and 13. A comparative analysis of the positions of previously published relevant QTLs allowed the identification of homologous regions that are associated with similar health traits in several species and which contain TLR related and other immunologically relevant genes. Additional evidence was gathered by examining relevant gene expression and association studies. CONCLUSION: This comparative genomic approach identified eight genes as potentially causative genes for variations of health related traits. These include susceptibility to clinical mastitis in dairy cattle, general disease resistance in sheep, cattle, humans and mice, and tolerance to protozoan infection in cattle and mice. Four TLR-related genes (TLR1, 6, MyD88, IRF3) appear to be the most likely candidate genes underlying QTL regions which control the resistance to the same or similar pathogens in several species. Further studies are required to investigate the potential role of polymorphisms within these genes.

Variation matters: TLR structure and species-specific pathogen recognition.

Toll-like receptors (TLRs) are a family of pattern recognition receptors that are an important link between innate and adaptive immunity. Many vaccines incorporate ligands for TLRs as an adjuvant and are developed in rodent models, with the resulting data transferred to other species. Vaccine features can be improved markedly by emphasizing the biological relevance when evaluating other animal models for host-pathogen interaction and by taking greater advantage of the unique experimental opportunities that are offered by large animal, non-rodent models. Here, we aim to summarize our current knowledge of species-specific TLR responses and briefly discuss that vaccine efficacy in relevant host species might be improved by considering the species-specific TLR responses.

Molecular cloning and characterization of Toll-like receptors 1-10 in sheep.

Toll-like receptors (TLRs) are pattern-recognition receptors that trigger innate immune responses and stimulate adaptive immunity. Currently, only partial information is available for sheep TLR genes. The aims of this study were to clone and sequence the coding regions of all 10 ovine TLR genes and compare the sequences with those of other mammalian species. The coding sequences for ovine TLRs 1-10 and the 3'-untranslated sequences for ovine TLR1, 6 and 10 have been obtained. Ovine TLR6 exhibited a distinctive 3'-end sequence that resembled a rare splice variant of bovine TLR6, but appeared to represent the major TLR6 transcript in the sheep. qRT-PCR confirmed the presence of TLR transcripts in blood mononuclear cells, alveolar macrophages, keratinocytes and lymph node tissues. Comparative sequence analysis showed that the sheep TLRs share high sequence similarity with the respective cattle, pig, human and mouse genes and are likely derived from the same ancestral sequence.

Molecular evolution of bovine Toll-like receptor 2 suggests substitutions of functional relevance.

BACKGROUND: There is accumulating evidence that polymorphism in Toll-like receptor (TLR) genes might be associated with disease resistance or susceptibility traits in livestock. Polymorphic sites affecting TLR function should exhibit signatures of positive selection, identified as a high ratio of non-synonymous to synonymous nucleotide substitutions (omega). Phylogeny based models of codon substitution based on estimates of omega for each amino acid position can therefore offer a valuable tool to predict sites of functional relevance. We have used this approach to identify such polymorphic sites within the bovine TLR2 genes from ten Bos indicus and Bos taurus cattle breeds. By analysing TLR2 gene phylogeny in a set of mammalian species and a subset of ruminant species we have estimated the selective pressure on individual sites and domains and identified polymorphisms at sites of putative functional importance. RESULTS: The omega were highest in the mammalian TLR2 domains thought to be responsible for ligand binding and lowest in regions responsible for heterodimerisation with other TLR-related molecules. Several positively-selected sites were detected in or around ligand-binding domains. However a comparison of the ruminant subset of TLR2 sequences with the whole mammalian set of sequences revealed that there has been less selective pressure among ruminants than in mammals as a whole. This suggests that there have been functional changes during ruminant evolution. Twenty newly-discovered non-synonymous polymorphic sites were identified in cattle. Three of them were localised at positions shaped by positive selection in the ruminant dataset (Leu227Phe, His305Pro, His326Gln) and in domains involved in the recognition of ligands. His326Gln is of particular interest as it consists of an exchange of differentially-charged amino acids at a position which has previously been shown to be crucial for ligand binding in human TLR2. CONCLUSION: Within bovine TLR2, polymorphisms at amino acid positions 227, 305 and 326 map to functionally important sites of TLR2 and should be considered as candidate SNPs for immune related traits in cattle. A final proof of their functional relevance requires further studies to determine their functional effect on the immune response after stimulation with relevant ligands and/or their association with immune related traits in animals.

A physical map of the bovine genome.

BACKGROUND: Cattle are important agriculturally and relevant as a model organism. Previously described genetic and radiation hybrid (RH) maps of the bovine genome have been used to identify genomic regions and genes affecting specific traits. Application of these maps to identify influential genetic polymorphisms will be enhanced by integration with each other and with bacterial artificial chromosome (BAC) libraries. The BAC libraries and clone maps are essential for the hybrid clone-by-clone/whole-genome shotgun sequencing approach taken by the bovine genome sequencing project. RESULTS: A bovine BAC map was constructed with HindIII restriction digest fragments of 290,797 BAC clones from animals of three different breeds. Comparative mapping of 422,522 BAC end sequences assisted with BAC map ordering and assembly. Genotypes and pedigree from two genetic maps and marker scores from three whole-genome RH panels were consolidated on a 17,254-marker composite map. Sequence similarity allowed integrating the BAC and composite maps with the bovine draft assembly (Btau3.1), establishing a comprehensive resource describing the bovine genome. Agreement between the marker and BAC maps and the draft assembly is high, although discrepancies exist. The composite and BAC maps are more similar than either is to the draft assembly. CONCLUSION: Further refinement of the maps and greater integration into the genome assembly process may contribute to a high quality assembly. The maps provide resources to associate phenotypic variation with underlying genomic variation, and are crucial resources for understanding the biology underpinning this important ruminant species so closely associated with humans.

A second generation radiation hybrid map to aid the assembly of the bovine genome sequence.

BACKGROUND: Several approaches can be used to determine the order of loci on chromosomes and hence develop maps of the genome. However, all mapping approaches are prone to errors either arising from technical deficiencies or lack of statistical support to distinguish between alternative orders of loci. The accuracy of the genome maps could be improved, in principle, if information from different sources was combined to produce integrated maps. The publicly available bovine genomic sequence assembly with 6x coverage (Btau_2.0) is based on whole genome shotgun sequence data and limited mapping data however, it is recognised that this assembly is a draft that contains errors. Correcting the sequence assembly requires extensive additional mapping information to improve the reliability of the ordering of sequence scaffolds on chromosomes. The radiation hybrid (RH) map described here has been contributed to the international sequencing project to aid this process. RESULTS: An RH map for the 30 bovine chromosomes is presented. The map was built using the Roslin 3000-rad RH panel (BovGen RH map) and contains 3966 markers including 2473 new loci in addition to 262 amplified fragment-length polymorphisms (AFLP) and 1231 markers previously published with the first generation RH map. Sequences of the mapped loci were aligned with published bovine genome maps to identify inconsistencies. In addition to differences in the order of loci, several cases were observed where the chromosomal assignment of loci differed between maps. All the chromosome maps were aligned with the current 6x bovine assembly (Btau_2.0) and 2898 loci were unambiguously located in the bovine sequence. The order of loci on the RH map for BTA 5, 7, 16, 22, 25 and 29 differed substantially from the assembled bovine sequence. From the 2898 loci unambiguously identified in the bovine sequence assembly, 131 mapped to different chromosomes in the BovGen RH map. CONCLUSION: Alignment of the BovGen RH map with other published RH and genetic maps showed higher consistency in marker order and chromosome assignment than with the current 6x sequence assembly. This suggests that the bovine sequence assembly could be significantly improved by incorporating additional independent mapping information.

Genetic diversity, introgression and relationships among West/Central African cattle breeds.

Genetic diversity, introgression and relationships were studied in 521 individuals from 9 African Bos indicus and 3 Bos taurus cattle breeds in Cameroon and Nigeria using genotype information on 28 markers (16 microsatellite, 7 milk protein and 5 blood protein markers). The genotypes of 13 of the 16 microsatellite markers studied on three European (German Angus, German Simmental and German Yellow) and two Indian (Nelore and Ongole) breeds were used to assess the relationships between them and the African breeds. Diversity levels at microsatellite loci were higher in the zebu than in the taurine breeds and were generally similar for protein loci in the breeds in each group. Microsatellite allelic distribution displayed groups of alleles specific to the Indian zebu, African taurine and European taurine. The level of the Indian zebu genetic admixture proportions in the African zebus was higher than the African taurine and European taurine admixture proportions, and ranged from 58.1% to 74.0%. The African taurine breed, Muturu was free of Indian zebu genes while its counter Namchi was highly introgressed (30.2%). Phylogenic reconstruction and principal component analysis indicate close relationships among the zebu breeds in Cameroon and Nigeria and a large genetic divergence between the main cattle groups--African taurine, European taurine and Indian zebu, and a central position for the African zebus. The study presents the first comprehensive information on the hybrid composition of the individual cattle breeds of Cameroon and Nigeria and the genetic relationships existing among them and other breeds outside of Africa. Strong evidence supporting separate domestication events for the Bos species is also provided.

High polymorphism in the kappa-casein (CSN3) gene from wild and domestic caprine species revealed by DNA sequencing.

We assessed polymorphisms in exon IV of the kappa-casein gene (CSN3) in ten different breeds of domestic goat (Capra hircus) from three continents and in three related wild caprine taxa (Capra ibex, Capra sibirica and Capra aegagrus). Thirty-five DNA samples were sequenced within a 558 bp fragment of exon IV. Nine polymorphic sites were identified in domestic goat, including four new polymorphisms. In addition to four previously described polymorphic positions, a total of 13 polymorphisms allowed the identification of 13 DNA variants, corresponding to 10 protein variants. Because of conflicting nomenclature of these variants, we propose a standardized allele designation. CSN3*A, CSN3*B, and CSN3*D were found as widely distributed alleles in European goat breeds. Within Capra ibex we identified three variants and showed that the sequence of Capra aegagrus is identical to the most common Capra hircus variant, consistent with Capra aegagrus being the wild progenitor of domestic goats. A dendrogram was drawn to represent the molecular network between the caprine CSN3 variants.

Geographic distribution of haplotype diversity at the bovine casein locus.

The genetic diversity of the casein locus in cattle was studied on the basis of haplotype analysis. Consideration of recently described genetic variants of the casein genes which to date have not been the subject of diversity studies, allowed the identification of new haplotypes. Genotyping of 30 cattle breeds from four continents revealed a geographically associated distribution of haplotypes, mainly defined by frequencies of alleles at CSN1S1 and CSN3. The genetic diversity within taurine breeds in Europe was found to decrease significantly from the south to the north and from the east to the west. Such geographic patterns of cattle genetic variation at the casein locus may be a result of the domestication process of modern cattle as well as geographically differentiated natural or artificial selection. The comparison of African Bos taurus and Bos indicus breeds allowed the identification of several Bos indicus specific haplotypes (CSN1S1*C-CSN2*A2-CSN3*AI / CSN3*H) that are not found in pure taurine breeds. The occurrence of such haplotypes in southern European breeds also suggests that an introgression of indicine genes into taurine breeds could have contributed to the distribution of the genetic variation observed.

VOC- and SVOC-emissions from adhesives, floor coverings and complete floor structures.

UNLABELLED: Emissions of volatile organic compounds (VOC) and semivolatile organic compounds (SVOC) from materials for flooring installation (primer, screed, adhesive, floor covering) were measured by means of emission test chambers and cells over a time period of at least 28 days at 23 degrees C, 50% relative humidity and an area specific air flow rate of q = 1.25 m(3)/m(2) h. Single components were tested in comparison to three complete structures (same concrete, primer, screed, adhesive) with different types of floor covering (PVC, carpet, linoleum). Sorption into concrete/screed and different permeability of flooring materials affected the emissions from the complete structures. The complete structures with linoleum and PVC showed the same types of emission and emission rates as the individual floor coverings themselves. Emissions from the carpet-covered structure resulted also from the lower layers. In all cases emissions from the complete structures were lower than the sum of emissions from the single components. For two adhesives the formation of secondary emissions (aldehydes and organic acids) was observed starting after the standard testing time of 28 days. PRACTICAL IMPLICATIONS: This paper gives a survey of possible emissions of VOCs and SVOCs from flooring materials and adhesives. On the example of these materials it is shown that the determination of SVOC-emissions from materials is important because after a few weeks the emission rates for SVOCs might be higher than for VOCs. In the real indoor environment SVOCs will be probably adsorbed to dust but by means of emission test chambers or cells the determination of emission rates from materials is possible. With the knowledge of this "emission potential" it is possible to estimate also the release of SVOCs into the (indoor) environment.

Gene-culture coevolution between cattle milk protein genes and human lactase genes.

Milk from domestic cows has been a valuable food source for over 8,000 years, especially in lactose-tolerant human societies that exploit dairy breeds. We studied geographic patterns of variation in genes encoding the six most important milk proteins in 70 native European cattle breeds. We found substantial geographic coincidence between high diversity in cattle milk genes, locations of the European Neolithic cattle farming sites (>5,000 years ago) and present-day lactose tolerance in Europeans. This suggests a gene-culture coevolution between cattle and humans.