National land use specific reference values: a basis for maximum values in Dutch soil policy

The National Institute for Public Health and the Environment has derived Reference Values for maximum permissible soil pollution. The Netherlands Ministry of Housing, Spatial Planning and the Environment (VROM) used these values as a basis for the maximum values for soil pollution. The ministry set these values down according to a proposal for an update of soil policy and the Soil Protection Act in 2003. Reference values refer to allowed concentrations of pollutants in soil, depending on the land use. The soil concentrations of pollutants with values below these concentrations meet all the requirements. The risks for humans, the ecosystem and agriculture were analyzed as critical factors, with risk thresholds derived for different types of land use, such as playgrounds, gardens, and agricultural and nature areas. Furthermore, an accelerated procedure was used to compile a complete list of reference values in 2006. The RIVM used state-of-the-art knowledge to complete the 'old' knowledge for information on toxicity of substances; figures were used where knowledge gaps occurred. A recommendation for the coming years is to address resulting inconsistencies in the list of reference values.Het RIVM heeft de referentiewaarden afgeleid waarmee het ministerie van VROM de maximaal toelaatbare bodemverontreinigingen onderbouwt (maximale waarden). Het ministerie heeft deze normen ingesteld in lijn met zijn voorstel uit 2003 om het bodembeleid en de Wet bodembescherming te actualiseren. Referentiewaarden zijn concentraties van verontreinigende stoffen in de bodem die, afhankelijk van het bodemgebruik, zijn toegestaan. Onder deze concentraties voldoet de bodem aan alle eisen. Voor verschillende vormen van bodemgebruik, zoals landbouw, kinderspeelplaatsen of industrie, zijn grensgehalten voor risico's bepaald. Dat zijn bijvoorbeeld, afhankelijk van het gebruik, risico's voor de mens, voor het ecosysteem en voor de landbouw. Het RIVM heeft gebruikgemaakt van een versnelde procedure om in 2006 een compleet voorstel van referentiewaarden gereed te hebben. Die snelheid was ingegeven door de werkgroep NOBO (normstelling en bodemkwaliteitsbeoordeling). Deze werkgroep heeft tevens uitgangspunten en beslissingen geformuleerd op basis waarvan het RIVM de referentiewaarden heeft afgeleid. Het RIVM heeft voor zijn onderzoek zo veel mogelijk gebruikgemaakt van de nieuwste kennis en inzichten, voor zover die beschikbaar zijn. Deze informatie is aangevuld met 'oude' kennis over stoffen. Deze combinatie heeft evenwel tot inconsistenties geleid in de afleiding van referentiewaarden. Het RIVM beveelt daarom aan de komende jaren aandacht te besteden aan de inconsistenties en zwakke plekken van de referentiewaarden

Variability in the Dynamics of Mortality and Immobility Responses of Freshwater Arthropods Exposed to Chlorpyrifos

The species sensitivity distribution (SSD) concept is an important probabilistic tool for environmental risk assessment (ERA) and accounts for differences in species sensitivity to different chemicals. The SSD model assumes that the sensitivity of the species included is randomly distributed. If this assumption is violated, indicator values, such as the 50% hazardous concentration, can potentially change dramatically. Fundamental research, however, has discovered and described specific mechanisms and factors influencing toxicity and sensitivity for several model species and chemical combinations. Further knowledge on how these mechanisms and factors relate to toxicologic standard end points would be beneficial for ERA. For instance, little is known about how the processes of toxicity relate to the dynamics of standard toxicity end points and how these may vary across species. In this article, we discuss the relevance of immobilization and mortality as end points for effects of the organophosphate insecticide chlorpyrifos on 14 freshwater arthropods in the context of ERA. For this, we compared the differences in response dynamics during 96 h of exposure with the two end points across species using dose response models and SSDs. The investigated freshwater arthropods vary less in their immobility than in their mortality response. However, differences in observed immobility and mortality were surprisingly large for some species even after 96 h of exposure. As expected immobility was consistently the more sensitive end point and less variable across the tested species and may therefore be considered as the relevant end point for population of SSDs and ERA, although an immobile animal may still potentially recover. This is even more relevant because an immobile animal is unlikely to survive for long periods under field conditions. This and other such considerations relevant to the decision-making process for a particular end point are discussed

Hazardous concentrations of pollutants for micro-organisms in river sediment

The toxic effects of 5 toxicants on 5 anaerobic microbial processes in fresh water sediments were measured. Four 14-C labelled substrates were mineralized to 14-CO2 at concentrations from 1-4 mug/l in fresh sediment microcosms. The half-lives of the substrates acetate, benzoate and 4-monochlorophenol were 12-30, 24, and 84 min. respectively. The chloroform mineralization was much slower with a half-life of 4.5 - 12 days. The natural methane production in the sediment was also used to measure the toxic effects. A dangerous Concentration 5% (DC5) can be calculated from the toxicity data using methods previously adapted for single animal species toxicity tests. Above this toxicant concentration more than 5% of the possible mineralization reactions can be partly inhibited. The HC5 concentrations for benzene, pentachlorophenol, 1,2-dichloroethane, chloroform and zinc are 1, 0.39, 0.0004, 0.0001 and 270 mg/kg sediment dry weight respectively. The chlorinated alkanes are much more toxic for anaerobic micro-organisms than for aerobic fish.<br

Maximaal toelaatbare concentratie&apos;s en verwaarloosbare concentratie&apos;s van aangroeiwerende middelen: Irgarol 1051, dichlofluanide, ziram, chloorthalonil en TCMTB

In dit rapport zijn maximaal toelaatbare concentratie's en verwaarloosbare concentratie's afgeleid voor diverse aangroeiwerende middelen, welke worden gebruikt als vervanger voor TBT zoals Irgarol 1051, dichlofluanide, ziram, chloorthalonil en TCMTB.This report presents maximum permissible concentrations and negligible concentrations that have been derived for various antifouling substances used as substitutes for TBT. Included here are Irgarol 1051, dichlofluanide, ziram, chlorothalonil and TCMTB.DGM-SA

Toxic Effects of Pollutants on Methane Production of River Sediment

The effects of five compounds on the endogenous methane production of sediment samples of the river Rhine were examined. The concentrations of a toxicant that inhibited the methane production for 10% and 50% are called EC10 and EC50. Benzene, 1,2- dichloroethane, pentachlorophenol and chloroform had EC10 values of >10000, 860, 140 and 5.5 mg/kg dry sediment, respectively. These values are well above the actual field concentrations, so the methane production is not inhibited. In one experiment, added zinc was toxic at concentrations far below the present background concentration in the sediment (800 mg Zn/kg) with an EC10 of 48 mg Zn.kg. In a second experiment with another sediment, however, the EC10 value was 1780 mg/kg. The difference in sensitivity is probably due to a different availability of zinc in the two experiments. Factors that govern the speciation of zinc in the sediment (e.g. the concentration of sulfide) are thus important when considering possible effects of zinc on microbial activity. Insight in these mechanisms, which also apply for other heavy metals, is needed as it was shown that zinc can be toxic at very low concentrations.<br

[Toxische effecten van verontreinigingen op de mineralisatie van 4-chloorfenol en benzoaat in methanogeen riviersediment.]

The toxic effects of pollutants on the mineralization of 2 mug/l [U-14C] 4-chlorophenol and benzoate were studied in microcosms with methanogenic sediment from the Rhine river. In contrast with studies using a high substrate concentration no lag time was observed and the half-lives for 4-chlorophenol and benzoate were 1.6 and 0.55 hours, respectively. The effect of increasing additions of benzene, chloroform, 1,2-dichloroethane, pentachlorophenol and zinc on each mineralization reaction was measured. Toxicity data were fitted with a logistic dose-effect curve. The IC10 is defined as the concentration of a toxicant inhibiting the mineralization rate for 10%. The IC10 concentration of benzene, chloroform, 1,2-dichloroethane, pentachlorophenol and zinc on the benzoate mineralization was 150, 0.04, 71, 6 and 842 mg/kg sediment d.w. respectively. This latter value includes the background concentration of 800 mg Zn/kg sediment. The mineralization of 4-chlorophenol and benzoate showed similarities in the sensitivity for these toxicants. 4-Chlorophenol can be degraded via benzoate which might explain the similarities in sensitivity of both mineralization reactions. Chloroform proved to be extremely toxic to anaerobic mineralization reactions, probably due to the formation of very toxic and reactive intermediates formed during the slow anaerobic degradation of the chloroform in anaerobic sediments. Sediment quality criteria derived solely from standard toxicity tests using aerobic organisms, may lead to complete inhibition of several important microbial processes in anaerobic sediments.DGM/DW

Risico concentraties van verontreinigingen voor micro-organismen in rivier sediment

The toxic effects of 5 toxicants on 5 anaerobic microbial processes in fresh water sediments were measured. Four 14-C labelled substrates were mineralized to 14-CO2 at concentrations from 1-4 mug/l in fresh sediment microcosms. The half-lives of the substrates acetate, benzoate and 4-monochlorophenol were 12-30, 24, and 84 min. respectively. The chloroform mineralization was much slower with a half-life of 4.5 - 12 days. The natural methane production in the sediment was also used to measure the toxic effects. A dangerous Concentration 5% (DC5) can be calculated from the toxicity data using methods previously adapted for single animal species toxicity tests. Above this toxicant concentration more than 5% of the possible mineralization reactions can be partly inhibited. The HC5 concentrations for benzene, pentachlorophenol, 1,2-dichloroethane, chloroform and zinc are 1, 0.39, 0.0004, 0.0001 and 270 mg/kg sediment dry weight respectively. The chlorinated alkanes are much more toxic for anaerobic micro-organisms than for aerobic fish.DGM/HDM-DWL /Kroes H