The European water-based environmental quality standard for pentachlorophenol is NOT protective of benthic organisms.

Risk management of toxic substances is often based on Environmental Quality Standards (EQS) set for the water compartment, assuming they will also protect benthic organisms. In the absence of experimental data, EQS for sediments can be estimated by the equilibrium partitioning approach. The present study investigates whether this approach is protective of benthic organisms against pentachlorophenol (PCP), a legacy contaminant and EU priority substance still used in some parts of the world. Three freshwater species of invertebrates with different life cycles and feeding behaviors (the oligochaetes Lumbriculus variegatus, Tubifex tubifex and the dipteran insect Chironomus riparius) were exposed to PCP spiked sediments (2.10-46.03mgPCP/kg d.w. plus controls) in laboratory standard tests. Exposure duration was 28days for T. tubifex and L. variegatus and 10 and 28days for C. riparius; according to the corresponding OECD guidelines. For each investigated end-point, dose-response data were normalized to the mean control and fitted to a four-parameter log-logistic model for calculating the corresponding EC50 and EC10. The ranges for EC50 and EC10 estimates were 4.39 (Chironomus riparius-emergence)-27.50 (Tubifex tubifex-cocoon) and 0.30 (T. tubifex-young worms) -16.70 (T. tubifex-cocoon) mg/kg d.w., respectively. The EC50 and the EC10 values of L. variegatus were within these ranges. Following the EU Technical Guidance for deriving EQS, the lowest EC10 value of 0.30mg/kg (T. tubifex-young worms) resulted in a PCP quality standard (QS) for sediments of 30ng/g, about one fourth of the tentative QS of 119ng/g estimated by the equilibrium partitioning (EqP) approach. The response of benthic biota to PCP varied across organisms and across end-points for the same organism, so that the use of sediment PCP-QS calculated using the EqP-approach may be under-protective of the most sensitive organisms. Information on the possible effects of PCP on resident organisms must therefore be collected for appropriately managing aquatic systems.

Ecotoxicity of chlorophenolic compounds depending on soil characteristics.

Three chlorophenolic compounds (2-chlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol) were tested to assess their effects on two soils with different properties: a granitic soil (Haplic Arenosol) and a calcareous one (Calcaric Regosol). Different concentrations of the pollutants (ranging from 0.001 to 10,000 mg kg(-1) soil, d.w.) were assayed for their effects on soil microbial activity and composition, using manometric respirometry and PCR-DGGE analysis, respectively. Other ecotoxicity tests such as Lactuca sativa seedling growth in the contaminated soils and algal growth inhibition (Pseudokirschneriella subcapitata) in their water extracts were done. The behaviour of the pollutants in the soils with respect to biodegradability and volatilization was also investigated. In the Haplic Arenosol, volatilization is the main process affecting 2-chlorophenol. Degradation and fixation of this compound in the soil matrix are favored in the Calcaric Regosol. This is the least toxic pollutant assayed. For 2,4,6-trichlorophenol, the soil pH is a critical parameter in the toxicity assays due to the neutral pKa of the compound. It is toxic in the soil microbial activity assay, but some recovery of the biotic processes can be observed, particularly in the Calcaric Regosol. This compound is more toxic in the Haplic Arenosol than in the Calcaric Regosol. Pentachlorophenol is ionized in both soils due to its low pKa, increasing its water solubility. It is highly toxic to the soil microbiota, thus inhibiting respiration, biodegradation and other biotic dissipation processes. Plant and alga tests, were more sensitive than soil microbial tests, except for PCP. The microbial populations tend to show changes at lower concentrations than the microbial activity. Some soil types (abundant in the Mediterranean area), with alkaline pH and fine textures could show higher level of ecotoxicity for ionizable organic pollutants than the soil type recommended by the OECD in ecotoxicity testing.

Suppression of mouse complement activity by contaminants of technical grade pentachlorophenol.

Pentachlorophenol (PCP) is an antimicrobial agent used chiefly for the preservation of wood. Subchronic oral exposure (14 days) to Technical Grade PCP significantly inhibited the functional activity of female B6C3F1 mouse complement when measured in a microtiter hemolytic assay. When evaluated one day following the final exposure the highest administered dose (100 mg/kg) significantly suppressed the Classical complement pathway, the Spontaneous C1 autoactivation pathway, the Alternate pathway and the level of complement component, C3. Reconstitution studies using C5-deficient serum also demonstrated deleterious effects on this complement component. The Classical pathway was the most sensitive to Technical Grade PCP effects. Animals treated with 100 mg/kg Technical Grade PCP had CH 50 levels 30% of vehicle controls. Animals treated for 14 days and allowed a 15 day recovery period had CH 50 values 36% of control and animals which recovered for 30 days had only 52% of the complement activity of control animals. C3 recovery studies also demonstrated continued suppression on days 15 and 30 post-final exposure. Doses of 10 and 30 mg/kg did not produce the marked effects observed with the highest dose; however, a dose-dependent trend was observed for all responses. Animals treated with 100 mg/kg of EC-7, a PCP preparation with reduced amounts of contaminating dioxins and dibenzofurans, did not demonstrate detrimental effects on the complement system.