Dietary and environmental estrogens and antiestrogens and their possible role in human disease

Recent reports have suggested that dietary and environmental estrogens such as organochlorine pollutants may play a role in the increased incidence of breast cancer in women and disorders of the male reproductive tract. For example, elevated levels of DDE and polychlorinated biphenyls (PCB) have been measured in women with breast cancer. However, it should also be noted that numerous environmental and dietary compounds have also been characterized as antiestrogenic and as inhibitors of mammary cancer cell growthin vitro and/orin vivo. Some of these compounds include 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds, polynuclear aromatic hydrocarbons (PAH), other naturally-occurring TCDD receptor agonists, retinoids, phorbol esters, terpenes, fatty acids, and polysaccharides. Thus, it is possible that dietary and environmental estrogens and antiestrogens may be contra-active, and these interactions must be considered in the overall risk assessment of the potential adverse human and environmental health impacts of these chemicals.     

Surfactant solubilization of hydrophobic compounds in soil and water

Reductions in the apparent soil-water partition coefficients (K_d ^*) for 28 polychlorinated biphenyls (PCBs) caused by the surfactant sodium dodecylsulphate (SDS) in the aqueous phase were studied. Above the critical micelle concentration (CMC) of the surfactant, K_d ^* was reduced by 2–3 orders of magnitude, but even far below CMC at environmentally relevant surfactant concentrations significant reductions in K_d ^* were observed. The plot of the soil-water partition coefficient (K_d) divided by K_d ^* versus the concentration of SDS allowed for the calculation of monomer (K_mn ^oc) and micellar (K_mc ^oc) surfactant-water partition coefficients normalized to organic carbon for each PCB congener. K_mn ^oc values were comparable with published values for the partition of PCBs between natural dissolved organic matter and lake water. K_mc ^oc values were up to 30 times higher than K_mn ^oc values and comparable with published octanol-water distribution coefficients. The findings of the present study underline the potential of surfactants at concentrations below their CMC to mobilize otherwise strongly bound hydrophobic compounds in soil-water systems.     

Toxicity testing of highly volatile chemicals with green algae

A gas-tight system for toxicity testing of highly volatile chemicals with the green algaChlamydomonas reinhardtii was developed. The procedure permits maintenance of constant and defined concentrations of the tested compounds in the vessels. To ensure sufficient CO₂-supply, new bipartite test vessels were used. These vessels allowed spatial separation of a HCO₃-/CO ₃ ^2? buffer used for CO₂ supply and the alga culture to avoid growth inhibition due to ionic strength. Several volatile chlorinated hydrocarbons have been tested. Their EC10 values were several orders of magnitude lower than those obtained with open test systems.     

Uptake and metabolism of 2,4,6-trinitrotoluene in higher plants

The fate of the explosive 2,4,6-TNT in plants is of major interest. Therefore, a method was developed to analyse TNT and derivatives in plant tissue. The method was utilized to investigate the uptake and metabolism of TNT inMedicago sativa andAllium schoenoprasum grown in hydroponic cultures containing TNT levels of 0.1 to 10 mg/1. Detectable concentrations of nitrotoluenes were significantly higher inAllium schoenoprasum than inMedicago sativa. The uptake of TNT in plants was directly related to the initial TNT level. The principal nitroaromatic components in roots and shoots of both plant species were identified as 4-ADNT and 2-ADNT in equal amounts, with substantially less TNT.     

Immunoassay monitoring of polychlorinated biphenyls (PCBs) in the Great Lakes

Although polychlorinated biphenyls (PCBs) are no longer manufactured, they are still entering the environment. In some compartments of the environment, PCB concentrations are a serious concern. This is especially true in compartments which accumulate PCBs, and in food items consumed by humans and wildlife. Also, there are situations in which management decisions require rapid, sensitive, accurate measurements, which can be made in real time under field conditions. Methods to use an enzyme-linked immunosorbent assay (ELISA) for PCBs were developed and applied to sediments and fish muscle homogenates collected from the Great Lakes. The extraction methods developed can be applied in the field with non-hazardous solvents, in the absence of sophisticated laboratory equipment. The method detection limit for PCBs in dimethyl sulfoxide (DMSO) extracts of sediment was 0.9 mg/kg. For PCBs in isopropanol extracts of fish tissue, the method detection limit was 0.6 mg/kg. The resolution of the ELISA was 0.83 mg/kg at 1.1 mg/kg and 1.6 mg/kg at 1.7 mg/kg, for sediment and fish tissue, respectively.     

Deposition of semivolatile organic compounds to spruce needles

The deposition of atmospheric tetrachlorobenzene, pentachlorobenzene, hexachlorobenzene, α-HCH, γ-HCH, DDT, DDE and the PCB congeners 52, 101, 138, 153 and 180 to spruce needles (Picea abies) was estimated for a period of 9 months. Accumulation in spruce as a result of dry gaseous deposition, particle bound deposition and wet deposition was calculated on the basis of the corresponding deposition rates and the compounds’ concentrations in the different atmospheric compartments. The comparison of the calculated values with the concentrations of the compounds measured in 9-month-old spruce needles showed that for many compounds each deposition pathway could explain a large part of the concentrations found in the needles.     

Environmental Hazard- Assessment of chemicals and products

Part II: Persistence and Degradability of Organic Chemicals The criteria “Persistence” and “Degradability” are defined and explained, starting from the “functional” definition of the environment. In this definition, theenvironment is the counterpart of thetechnosphere, which consists of all processes controlled by man. A substance is persistent if there are no sinks (degradation processes). It is shown that persistence is the central and most important critérium of environmental hazard assessment of organic chemicals. It follows that all substances released into the environment should be degradable, preferentially into small inorganic molecules (mineralization). As examples for persistent substances, the polychlorinated biphenyls (PCB), the chlorofluorohydrocarbons (CFC), bis (2-ethylhexyl) phthalate (DEHP), and 2,3,7,8-tetrachloro-dibenzo-dioxin (TCDD) are discussed. Finally, an attempt to quantify persistence is made.     

Environmental hazard — Assessment of chemicals and products

Part III: The Limits to Single Compound Assessment The principles and basic assumptions of single compound assessment are briefly reviewed. Limitations to this approach are shown, especially with regard to complex mixtures of similar substances, substitution products, and complicated (final) products containing chemicals and materials produced by the chemical industry. A new thinking in product lines and life cycles is emerging, leading to new assessment methods. In some cases, substitution has not improved the environmental performance of products, since very similar chemicals were used as substitutes.     

Environmental risk assessment of existing chemicals

Most of the existing chemicals of high priority have been released into the environment for many years. Risk assessments for existing chemicals are now conducted within the framework of the German Existing Chemicals Program and by the EC Regulation on Existing Substances. The environmental assessment of a chemical involves:

1. exposure assessment leading to the derivation of a predicted environmental concentration (PEC) of a chemical from releases due to its production, processing, use, and disposal. The calculation of a PEC takes into account the dispersion of a chemical into different environmental compartments, elimination and dilution processes, as well as degradation. Monitoring data are also considered.
2. effects assessment. Data obtained from acute or long-term toxicity tests are used for extrapolation on environmental conditions. In order to calculate the concentration with expectedly no adverse effect on organisms (Predicted No Effect Concentration, PNEC) the effect values are divided by an assessment factor. This assessment factor depends on the quantity and quality of toxicity data available.

In the last step of the initial risk assessment, the measured or estimated PEC is compared with the PNEC. This “risk characterization” is conducted for each compartment separately (water, sediment, soil, and atmosphere). In case PEC > PNEC an attempt should be made to revise data of exposure and/or effects to conduct a refined risk characterization. In case PEC is again larger than PNEC risk reduction measures have to be considered.     

Polychlorinated dibenzo-p-dioxins (PCDDs) and furans (PCDFs) in urban air and deposition in the United Kingdom

Polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) have been monitored in air and deposition at four UK urban sites (London, Cardiff, Manchester and Stevenage) since the beginning of 1991; data from the first 2 years are presented here. Median Σ2,3,7,8-substituted PCDD/F concentrations in air were 3.2, 4.0, 3.5 and 2.6 pg/m³ respectively for London, Cardiff, Manchester and Stevenage. Median Σ2,3,7,8-substituted PCDD/F deposition fluxes were 1.5 ng/m²/day in London, 1.4 ng/m²/day in Cardiff and Manchester and 0.79 ng/m²/day in Stevenage. Seasonal variations in the PCDD/F concentrations were observed at all sites for both air and deposition, with concentrations/fluxes generally elevated during the winter.     

Observations on long-term air-soil exchange of organic contaminants

Evidence for long-term changes in the soil composition of selected organic compounds, brought about by exchanges with the atmosphere, is briefly reviewed. In the case of some compounds — such as benzo(a)pyrene and octachlorodibenzo-p-dioxin, soils may be significant long-term environmental sinks for atmospherically-derived material. In other cases — such as phenanthrene and some of the lighter PCBs, de-gassing or volatilisation from soil back to the air can occur under certain conditions. Hence the soil may act as a “short-term” sink, and a potential source to atmosphere. Indeed, for some ‘semi-volatile’ compounds used in large quantities in the past — such as PCBs, soil outgassing may actually be an extremely important source to contemporary air. Furthermore, soil outgassing from areas of former high use may provide an important driving mechanism for continued “global cycling” of a range of semi-volatile organochlorine compounds.     

Simulation of pesticide runoff at Rosemaund Farm (UK) using the SoilFug model

A validation exercise of the SoilFug model using field runoff data from Rosemaund Farm (UK) is described. A comparison has been made of modelled and measured concentrations of several pesticides in surface water and soil during and after specific rain events following application. The field experiments were designed to obtain data on rainfall, outflows of water, pesticide application rates and concentrations in soil and water. The results were satisfactory for the undissociated pesticides (atrazine, carbofuran, dimethoate, isoproturon, lindane, simazine and trifluralin), whose concentrations in water were mostly predicted within an order of magnitude of measured data. The results for the dissociated pesticides (dichlorprop, MCPA, mecoprop) were less satisfactory, giving generally much higher predicted concentrations in water. The use of the SoilFug model is suggested for the calculation of predicted environmental concentrations (PECs) in water, since it generally produces acceptable results from a relatively small set of input data, most of which is generally available.     

Bioconcentration of superlipophilic persistent chemicals

According to present understanding, persistent superlipophilic chemicals — such as octachlorodibenzo-p-dioxin, octachlorodibenzofuran, Mirex etc — with log K_ow > 6 and cross sections > 9.5 Å, bioconcentrate in aquatic organisms only little from ambient water. The most convincing argument against it is that in bioconcentration experiments with superlipophilic chemicals amounts applied exceeded water solubility by several orders of magnitude. This paper describes various methods for determining bioconcentration factors (BCF) of superlipophilic compounds. As exemplified with octachlorodibenzo-p-dioxin, BCF values evaluated by these methods match well with those calculated by QSARs for fish and mussels based on log K_ow and water solubility. As expected, these BCF values exceed previous values by several orders of magnitude. For BCF evaluation of superlipophilic chemicals in aquatic organisms we recommend:

1. flow-through systems, kinetic method (OECD guideline No. 305 E)
2. ambient concentrations < water solubility
3. during the uptake and especially during the elimination phase no toxic effects of the test organisms should occur.

     

Determination of atrazine in rainfall and surface water by enzyme immunoassay

Rainwater and surface water from four sites in Germany (Bavaria and Lower Saxony) were analyzed for atrazine by enzyme immunoassay from June 1990 until October 1992. The limit of quantification of the immunoassay was 0.02 μg/L with a middle of the test at 0.2 μg/L. About 60 % of the samples contained measurable amounts of atrazine. Seasonal trends were observed, with the highest concentration in the summer months of up to 4 μg/L for rainwater and up to 15 μg/L for surface waters. The highest concentrations were found in agricultural areas, while in the investigated national parks up to 0.56 μg/L could be detected in rain water. This points to long-range atmospheric transport from agricultural areas to pristine national parks. Samples from forest stands usually showed higher atrazine concentrations than samples from open fields. Deposition rates of 10 – 50 μg/m² · yr were observed in the national parks and 10–180 μg/m² · yr at the agricultural sites. Comparison of results obtained by enzyme immunoassay and GC/MS showed a good correlation of r = 0.95.     

Adsorption of organic vapors on polar surfaces- Recent advances

This paper summarizes recent research on the adsorption of organic vapors on surfaces. Since the low gas phase concentration range is typical for environmental situations, this review is restricted to these adsorption coefficients. Two environmental parameters have a strong influence on the adsorption of organic vapors on polar surfaces:temperature andrelative humidity (which is the most suitable parameter for describing the influence of ambient moisture). An exponential relationship was found for the adsorption coefficientversus relative humidity and the reciprocal temperature, respectively. Comparing the heats of adsorption, two different groups of substances emerged: polar chemicals exhibited heats of sorption which were higher than their corresponding heats of condensation due to their ability to form hydrogen bonds, while for the nonpolar compounds the opposite was true. Sorption takes place on the surface of an adsorbed water film when the relative humidity exceeds the value which is necessary to form a monomolecular layer of water on the surface of the adsorbent (≥ 30 % relative humidity). Therefore, at temperature below 0 °C, a change in the adsorption behavior might be expected due to a change of properties of the adsorbed water film. However, no alterations were observed at temperatures from -12 °C to + 4 °C (adsorption on quartz sand). The results were comparable to those at much higher temperatures (50 – 80 °C). A statistical approach for the prediction of the adsorption coefficients from physico-chemical parameters of the substances (vapor pressure, polarizability, and electron-donating capability) was developed and good agreement was found with experimental results and independent data from the literature. Finally, two special cases, the adsorption on bulk water and ice, are discussed.     

Factors affecting degradation of dimethyl sulfoxide (DMSO) by fluidized-bed Fenton process

In this study, the target compound is dimethyl sulfoxide (DMSO), which is used as a photoresist stripping solvent in the semiconductor and thin-film transistor liquid crystal display (TFT-LCD) manufacturing processes. The effects of the operating parameters (pH, Fe²⁺ and H₂O₂ concentrations) on the degradation of DMSO in the fluidized-bed Fenton process were examined. This study used the Box-Behnken design (BBD) to investigate the optimum conditions of DMSO degradation. The highest DMSO removal was 98 % for pH 3, when the H₂O₂ to Fe²⁺ molar ratio was 12. At pH 2 and 4, the highest DMSO removal was 82 %, when the H₂O₂ to Fe²⁺ molar ratio was 6.5. The correlation of DMSO removal showed that the effect of the parameters on DMSO removal followed the order Fe²⁺?>?H₂O₂?>?pH. From the BBD prediction, the optimum conditions were pH 3, 5 mM of Fe²⁺, and 60 mM of H₂O₂. The difference between the experimental value (98 %) and the predicted value (96 %) was not significant. The removal efficiencies of DMSO, chemical oxygen demand (COD), total organic carbon (TOC), and iron in the fluidized-bed Fenton process were higher than those in the traditional Fenton process.     

Gaseous nitrogen losses from a forest site in the North Tyrolean Limestone Alps

Microorganisms are responsible for the mineralisation of organic nitrogen in soils. NH ⁺₄ can be further oxidised to NO₃ ⁻ during nitrification and NO₃ ⁻ can be reduced to gaseous nitrogen compounds during denitrification. During both processes, nitrous oxide (N₂O), which is known as greenhouse gas, can be lost from the ecosystem.

The aim of this study was to quantify N₂O emissions and the internal microbial N cycle including net N mineralisation and net nitrification in a montane forest ecosystem in the North Tyrolean Limestone Alps during an 18-month measurement period and to estimate the importance of these fluxes in comparison with other components of the N cycle. Gas samples were taken every 2 weeks using the closed chamber method. Additionally, CO₂ emission rates were measured to estimate soil respiration activity. Net mineralisation and net nitrification rates were determined by the buried bag method every month. Ion exchange resin bags were used to determine the N availability in the root zone.

Mean N₂O emission rate was 0.9 kg N ha⁻a⁻, which corresponds to 5 % of the N deposited in the forest ecosystem. The main influencing factors were air and soil temperature and NO ⁻₃ accumulated on the ion exchange resin bags. In the course of net ammonification, 14 kg NH ⁺₄ −N ha⁻ were produced per year. About the same amount of NO ⁻₃ −N was formed during nitrification, indicating a rather complete nitrification going on at the site. NO ^t-₃ concentrations found on the ion exchange resin bags were about 3 times as high as NO ^t-₃ produced during net nitrification, indicating substantial NO ^t-₃ immobilisation. The results of this study indicate significant nitrification activities taking place at the Mühleggerköpfl.