Volatile metabolites from mold growth on building materials and synthetic media

Mold species which were isolated from damp buildings were grown on sterile building materials and some synthetic media in order to study the microbial volatile organic compounds produced. Patterns of the microbial volatile organic compounds (MVOC) were very media dependent but media which favor terpene biosynthesis may give patterns unique enough for identification of dominant indoor molds.     

Biliary secretion,retention and excretion of five 14C-labelled polychlorinated biphenyls in the rat

Five ¹⁴C-labelled polychlorinated biphenyls: 2,4′,5-trichlorobiphenyl, 2,2′,4,5′-tetrachlorobiphenyl, 2,2′,4,5,5′-pentachlorobiphenyl, 2,2′,3,4,4′-pentachlorobiphenyl and 2,2′,4,4′,5,5′-hexachlorobiphenyl were administered orally to bile-cannulated rats. The activity secreted in the bile, excreted in the feces and the urine was determined. Residues of radioactivity in certain tissues and the carcass were also measured.The trichlorobiphenyl showed the highest absorption (93.8%±5.4) from the gastrointestinal tract and biliary secretion of radioactivity (87.6%±6.1 of the dose). The hexachlorobiphenyl showed the lowest absorption and biliary secretion, 28.2%±1.4 and 18.6%±1.3, respectively. The urinary excretion was low and the radioactive residues in the eviscerated carcasses increased with the chlorine content of the biphenyls.     

Dioxins: WHO's tolerable daily intake (TDI) revisited

In December 1990, the World Health Organization (WHO) established a tolerable daily intake (TDI) of 10 pg/kg b.w. (body weight) for TCDD, based on liver toxicity, reproductive effects and immunotoxicity in experimental animals, and making use of kinetic data in humans and experimental animals. Since then new epidemiological and toxicological data have emerged, in particular with respect to neurodevelopmental and endocrine effects of dioxin. Therefore, the European Centre for Environment and Health of the World Health Organization (WHO-ECEH) and the International Programme on Chemical Safety (IPCS) jointly organized a consultation on the "Assessment of the health risk of dioxins: re-evaluation of the TDI", May 1998, Geneva, Switzerland. The participants discussed the health risks for infants, cancer and non-cancer endpoints in humans and animals, mechanistic aspects, kinetic behaviour, modelling, exposure, and the applicability of the toxic equivalency (TEQ) concept. For the health risk assessment of dioxin-like compounds, the WHO Consultation focused on the most sensitive effects that are considered adverse (hormonal, reproductive and developmental effects) seen at low doses in animal studies (rats and monkeys). Human daily intakes corresponding with body burdens similar to those associated with adverse effects in animals could be estimated to be in the range of 14-37 pg/kg b.w./day. To arrive at a TDI expressed as TEQ, a composite uncertainty factor of 10 was recommended. By applying this uncertainty factor a TDI range of 1-4 pg TEQs/kg body weight was established. An extensive executive summary of the results of this WHO Consultation with all the underlying background documents will be published in Food Additives and Contaminants (in press).     

Metabolism, tissue disposition, and excretion of 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) in male Sprague-Dawley rats

A single oral dose of [14C] 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) was administered to conventional and bile-duct cannulated male Sprague-Dawley rats. Tissue disposition, excretion and metabolism was determined. BTBPE is a low-volume brominated flame retardant used in resins or plastics, and toxicity data in peer-reviewed journals is extremely limited. BTBPE was fairly insoluble in lipophilic solutions, which made dose preparation difficult. The great majority of 14C (>94%) was excreted in the feces of both groups of rats at 72 h, and tissue retention was minimal. Lipophilic tissues contained the highest concentrations of BTBPE, e.g. thymus, adipose tissue, adrenals, lung, and skin. Metabolites were excreted in the urine, bile and feces, but at a very low level. Fecal metabolites were characterized as monohydroxylated, monohydroxylated with debromination, dihydroxylated/debrominated on a single aromatic ring, monohydroxylated on each aromatic ring with accompanying debromination, and cleavage on either side of the ether linkage to yield tribromophenol and tribromophenoxyethanol. Despite a limited quantity of stable metabolites extractable in the feces, non-extractable 14C levels were relatively high (39% of the 0-24 h fecal 14C), which suggested that BTBPE could be metabolically activated in the rat and covalently bound to fecal proteins and/or lipids. It was concluded that limited absorption and metabolism of BTBPE would occur by ingestion in mammals.     

Volatile metabolites from indoor molds grown on media containing wood constituents

Since volatile mold metabolites are used for the detection of mold growth in buildings, it was interesting to determine whether different indoor mold species show different affinity for the major components of wood, a common building material. Growth and volatile metabolites were studied when Aspergillus versicolor, Penicillium chrysogenum, and P. palitans were grown on laboratory substrates containing the major wood constituents cellulose, xylan and lignin. Microbial volatile organic compounds (MVOCs) were characterized by thermal desorption/gas chromatography/mass spectroscopy. Growth and volatile metabolites varied considerably and there appeared to be complementary substrate specificities for P. chrysogenum, and P. palitans grown on cellulose and xylan. The failure of A. versicolor to produce characteristic MVOCs when grown on media containing wood constituents suggests that systems using volatile metabolites to detect microbial growth in buildings may be fundamentally unreliable for the detection of this species.     

Surfactant solubilization of hydrophobic compounds in soil and water

The soil/water partition coefficient (K_d) of hexachlorobenzene (HCB) ranged from 220 1/kg to 1800 1/kg for eight soils having a wide range of physico-chemical properties. K_d normalised to soil organic carbon (K_oc) was found to be 28000 ± 4800 1/kg. Anionic surfactant dodecylsulphate (DS) present at concentrations above the critical micellar concentration (CMC) caused reductions in the apparent soil/water partition coefficient (K_d ^*) in the range of 3–26 times for most soils and up to 36–91 times for sandy soils. Below CMC, at environmentally relevant surfactant concentrations, K_d ^* was reduced by a factor of 1–13. For clay and calcareous soils significant adsorption/complexation/precipitation of DS occurred. At the lowest DS concentration this produced a two-fold increase in K_d ^*. At increasing DS concentrations this effect was shielded by the solubihzing effect from DS. Monomer (K_mn) and micellar (K_mc) surfactant/water partition coefficients for HCB were determined to be, 980 ± 190 1/kg and 21000 ± 1600 1/kg, respectively.     

Convergent development of ecological,genetic, and morphological traits in native supercolonies of the red ant Myrmica rubra

Ant supercolonies (large networks of interconnected nests) represent the most extreme form of multi-queen breeding (polygyny) and have been found across ant lineages, usually in specific long-term stable populations. Many studies on the genetic population structure and demography of ant supercolonies have been done in recent decades, but they have lacked multicolonial control patches with separated colonies headed by a single or few queens so the origin of the supercolonial trait syndrome has remained enigmatic. Here, we set out to compare sympatric supercolonial and multicolonial patches in two natural Danish populations of the common red ant Myrmica rubra. We used DNA microsatellites to reconstruct genetic colony/population structure and obtained morphological and density measurements to estimate life history and ecology covariates. We found that supercolonies in both populations completely dominated their patches whereas colonies in multicolonial patches coexisted with other ant species. Supercolony patches had very low genetic differentiation between nests, negligible relatedness within nests, and lower inbreeding than multicolonial patches, but there were no significant morphological differences. One population also had nests that approached true outbred monogyny with larger workers and males but smaller queens than in the two other social nest types. Our results suggest that once smaller colonies start to adopt additional queens, they also gain the potential to ultimately become supercolonial when the habitat allows rapid expansion through nest budding. This is relevant for understanding obligate polygyny in ants and for appreciating how and why introduced North American populations of M. rubra have recently become invasive.     

Nutrient balance in the ecosystem of the North Western Adriatic Sea

The effects of biological processes on dissolved inorganic nutrients, dissolved organic nitrogen (DON) and phosphorus (DOP) are considered in the north western Adriatic Sea. The budgets of these nutrients, which represent the sum of production and consumption processes in comparison to advection, are discussed with regard to dissolved inorganic nitrogen ( 15 N labelled) uptake, which basically indicates the biological demand of this fraction of nitrogen by phytoplankton community. The presented data show that, although important, the continental input of dissolved inorganic nitrogen (DIN), mainly nitrate, is utilised and recycled within the coastal marine environment (budget of m 15 r µmol-N·dm m 3 ). In fact, during four cruises (June, 1996; February, 1997; June, 1997; February, 1998), phytoplankton production was mainly driven by regenerated nutrients ( f h 0.4). Regarding dissolved inorganic phosphorus (DIP), the negative budgets observed in most cases (down to m 0.4 r µmol-P·dm m 3 ) confirm, above all, its scarce availability in this basin. Recycling processes rather than continental inputs regulate the availability of this nutrient. In addition, the comparison between DIN and DIP budgets indicates that, in this ecosystem, dissolved inorganic phosphorus is recycled faster than nitrogen through the living particulate and dissolved organic pools. As a consequence of biological activities, a strong production of dissolved organic nitrogen (DON) can occur in summer (up to +22 r µmol-N·dm m 3 ) while DOP shows a more independent behaviour both with respect to its accumulation in the environment and to the observed nitrogen variations.     

Functional zoning for air quality

Environmental local agencies have to enforce European directives that impose a land classification, according to air quality status, to distinguish zones needing further actions from those needing only maintenance. This paper presents a land classification in zones featured by different criticality levels of atmospheric pollution, considering pollutant time series as functional data: we call this proposal “Functional Zoning”. Our proposal is articulated in order to also meet two specific requirements: upscaling pollutant concentration data to the municipality scale, since municipalities are the reference territorial administrative units for undertaking actions; aggregating different pollutants in order to provide a multi-pollutant zoning outcome reflecting the air quality status. Specifically, we present three different alternatives to upscale data from a regular grid to the municipality scale. Then, to aggregate by pollutant, we evaluate two strategies summarizing time series: the assessment of an air quality index and the use of the Multivariate Functional Principal Component Analysis (MFPCA). The partition of municipalities is obtained by clustering air quality time series and MFPCA scores. In particular, the proposed functional zoning is carried out for Piemonte (Northern Italy), considering the hourly concentration fields of the main pollutants. We obtain six classifications of the same land and we propose a comparison study of the different strategies’ results, by mapping and analyzing the differences between clusters’ labels. By taking into account the comparison study’s findings, we finally suggest an analysis strategy to environmental agencies and policy makers to obtain an easily interpretable outcome at a very reasonable computational cost.