Assessment of Soil Toxicity from an Antitank Firing Range Using Lumbricus terrestris and Eisenia andrei in Mesocosms and Laboratory Studies

Earthworm mesocosms studies were carried out on a explosives-contaminated site at an antitank firing range. Survival of earthworms and the lysosomal neutral red retention time (NRRT), a biomarker of lysosomal membrane stability, were used in these studies to assess the effect of explosives-contaminated soils on the earthworms Lumbricus terrestris and Eisenia andrei under field conditions. Toxicity of the soils samples for E. andrei was also assessed under laboratory conditions using the earthworms reproduction test and the NRRT. Results indicate that the survival was reduced up to 40% in certain explosive-contaminated soil mesocosms following 10 days of exposure under field conditions, whereas survival was reduced up to 100% following 28 days of exposure under laboratory conditions. Reproduction parameters such as number of cocoons and number of juveniles were reduced in many of the selected contaminated soils. Compared to the reference, NRRT was significantly reduced for E. andrei exposed to explosive-contaminated soils under both field and laboratory conditions, whereas for L. terrestris NRRT was similar compared to the reference mesocosm. Analyses showed that HMX was the major polynitro-organic compound in soils. HMX was also the only explosive detected in earthworm tissues. Thus, results from both field mesocosms and laboratory studies, showed lethal and sub-lethal effects associated to soil from the contaminated area of the antitank firing range.     

Oral bioavailability of pentachlorophenol from soils of varying characteristics using a rat model

Evidence accumulated during the last two decades suggests that only a fraction of any chemical in soil is available to organisms, and soil-related effects on bioavailability should be considered in optimizing soil remediation cleanup levels. In the current study, the absolute and relative bioavailabilities of pentachlorophenol (PCP) from freshly spiked and environmentally aged soils varying in organic carbon content, clay content, and pH were examined using a rat model. PCP is a broad-spectrum biocide widely used as a wood preservative, and thus is ubiquitous in the environment. Soils and corn oil containing equivalent levels of PCP were administered to male Sprague-Dawley rats by gavage at 2 dose levels: 100 and 200 microg/kg body weight. Equivalent doses were also given intravenously. The areas under the plasma concentration of PCP versus time curves were calculated, and absolute and relative bioavailabilities of PCP from each soil were determined. At a dose of 100 microg/kg body weight, the absolute bioavailabilities of PCP across soils ranged from 36% to 65%, and the relative bioavailabilities ranged from 48% to 82%. At the higher dose level (200 microg/kg body weight), absolute and relative bioavailability ranges were somewhat higher at 46% to 77% and 52% to 87%, respectively. All soils decreased absolute PCP bioavailability significantly at both dose levels and relative bioavailability at the lower PCP dose level. At the higher dose level, only one of the two field-contaminated soils decreased the relative PCP bioavailability. The data indicate that PCP-soil interactions do significantly decrease the oral bioavailability of PCP from soil, but no obvious correlation was observed between soil properties and bioavailabilities.     

Earthworm metabolomic responses after exposure to aged PCB contaminated soils

(1)H NMR metabolomics was used to measure earthworm sub-lethal responses to polychlorinated biphenyls (PCBs) in historically contaminated (>30?years) soils (91-280?mg/kg Aroclor 1254/1260) after two and 14?days of exposure. Although our previous research detected a distinct earthworm metabolic response to PCBs in freshly spiked soil at lower concentrations (0.5-25?mg/kg Aroclor 1254), the results of this study suggest only weak or non-significant relationships between earthworm metabolic profiles and soil PCB concentrations. This concurs with the expectation that decades of contaminant aging have likely decreased PCB bioavailability and toxicity in the field. Instead of being influenced by soil contaminant concentration, earthworm metabolic profiles were more closely correlated to soil properties such as total soil carbon and soil inorganic carbon. Overall, these results suggested that (1)H NMR metabolomics may be capable of detecting both site specific responses and decreased contaminant bioavailability to earthworms after only two days of exposure, whereas traditional toxicity tests require much more time (e.g. 14?days for acute toxicity and >50?days for reproduction tests). Therefore, there is significant opportunity to develop earthworm metabolomics as a sensitive tool for rapid assessment of the toxicity associated with contaminated field soils.     

Pentachlorophenol biodegradation and detoxification by the white‐rot fungus Phanerochaete chrysosporium

Pentachlorophenol (PCP) was widely used as a wood preservative and pesticide for several decades. Presently it is considered an ubiquitous contaminant, so it is important to find a good strategy to reduce PCP levels in the environment. One feasible option is using the ability of certain microorganisms to biodegrade pollutants and convert them into less toxic compounds. Phanerochaete chrysosporium, a white‐rot fungus, is recognized for its ability to metabolize a large diversity of compounds, including PCP, by the lignin degrading system. However, toxicity of PCP metabolic products generated by P. chrysosporium is not yet evaluated. The study's purpose is assessing toxicity resulting from PCP degradation by P. chrysosporium in soil and evaluating its potential usefulness in soil bioremediation. P. chrysosporium was cultured in a solid‐state system consisting of glass columns packed with crushed fibrous plant residue from sugar‐cane refining. Once the fungus grew, it was used to inoculate soil spiked with 100 ppm of PCP, at soil/plant residue ratio of 85/15. Under these conditions, PCP degradation kinetic study was performed for 11 days. Soil samples were collected during this period assessing PCP disappearance and soil toxicity changes using Microtox^®. A significant decrease (87%) in PCP levels in contaminated soil was observed 4 days after inoculation with P. chrysosporium. During this period, soil toxicity decreased rapidly, becoming almost negligible after 11 days. These results suggested P. chrysosporium application to PCP‐contaminated soil is a feasible bioremediation option, considering that this microorganism reduces PCP levels in a short period of time without generation of more toxic compounds. © 2000 John Wiley & Sons, Inc. Environ Toxicol 15: 107–113, 2000     

Cadmium toxicity for terrestrial invertebrates: taking soil parameters affecting bioavailability into account

Acute and chronic ecotoxicity tests with cadmium were conducted with the earthworm Eisenia fetida, the potworm Enchytraeus albidus and the springtail Folsomia candida. To assess the influence of the soil type on cadmium bioavailability, these tests were carried out in a standard artificial soil, in a sandy and a loamy field soil. It was not possible to evaluate the influence of soil parameters on the bioavailability on the basis of the experiments that were conducted in only three different soil types, therefore, literature data were also included. However, even in the same standard artificial soils, toxicity data in the literature for Eisenia fetida and Folsomia candida varied considerably. Consequently, no models could be developed that allow a normalization of the ecotoxicity of cadmium to parameters controlling bioavailability. In contrast to zinc, effect concentrations of cadmium for terrestrial invertebrates were always much higher than background concentrations. As the effect of aging on the bioavailability of cadmium was never taken into account, because toxicity experiments were always carried out in freshly spiked soils, these effect concentrations may even be regarded as conservative. Furthermore, the zinc–cadmium ratio in soils is usually so high that the risk of zinc ecotoxicity for terrestrial invertebrates will usually be much greater in comparison to cadmium ecotoxicity.     

Developmental toxicity of N-methyl-2-pyrrolidone in rats following inhalation exposure.

The developmental toxicity of inhaled N-methyl-2-pyrrolidone (NMP) was studied in Sprague-Dawley rats. Pregnant rats were exposed whole body to NMP vapours at concentrations of 0, 30, 60 and 120 ppm, 6 h/day, on gestational days (GD) 6 through 20. Maternal body weight gain was significantly decreased at 60 and 120 ppm on GD 6-13 and maternal food consumption was reduced at 120 ppm on GD 13-21. No significant difference in the gestational weight change corrected for the weight of the gravid uterus was observed, whatever NMP concentration. There were no adverse effects on embryo/fetal viability or evidence of teratogenicity at any concentration tested. Fetal toxicity indicated by reduced fetal weight was observed at 120 ppm. Thus, the no-observed-adverse-effect level (NOAEL) for maternal and developmental toxicity was 30 and 60 ppm, respectively.     

Assessing bioavailability and toxicity of permethrin and DDT in sediment using matrix solid phase microextraction

Matrix solid phase microextraction (matrix-SPME) was evaluated as a surrogate for the absorbed dose in organisms to estimate bioavailability and toxicity of permethrin and dichlorodiphenyltrichloroethane (DDT) in laboratory-spiked sediment. Sediments were incubated for 7, 28, and 90 days at room temperature to characterize the effect of aging on bioavailability and toxicity. Sediment toxicity was assessed using two freshwater invertebrates, the midge Chironomus dilutus and amphipod Hyalella azteca. Disposable polydimethylsiloxane fibers were used to estimate the absorbed dose in organisms and to examine bioavailability and toxicity. The equilibrium fiber concentrations substantially decreased with an increase in sediment aging time, indicating a reduction in bioavailability. Based on median lethal fiber concentrations (fiber LC50), toxicity of permethrin was not significantly different among the different aging times. Due to the substantial degradation of DDT to dichlorodiphenyldichloroethane (DDD) in sediment, sediment toxicity to C. dilutus increased, while it decreased for H. azteca with extended aging times. A toxic unit-based fiber LC50 value represented the DDT mixture (DDT and DDD) toxicity for both species. Significant linear relationships were found between organism body residues and the equilibrium fiber concentrations for each compound, across aging times. The study suggested that the matrix-SPME fibers mimicked bioaccumulation in the organisms, and enabled estimation of body residues, and could potentially be used in environmental risk assessment across matrices (e.g. sediment and water) to measure bioavailability and toxicity of hydrophobic pesticides.     

Lysosomal membrane response of earthworm, Eisenia fetida, to arsenic contamination in soils

Earthworm (Eisenia fetida) were exposed to sandy soils contaminated with arsenate (0.01-0.3 micromol g(-1)) for 28 days. Lysosomal membrane stability was used as a biomarker to determine the applicability of neutral-red retention times (NRRTs) for arsenic (As) toxicity to earthworm in soils. Total As and As speciation were analyzed to evaluate dose-response relationship between As accumulation and NRRTs and to observe the role of As metabolism in earthworms on a subcellular level toxicity. Significant decrease of NRRTs was found with the increasing As concentration in soils (ANOVA, P < 0.05). Adverse effects on earthworm survival and growth did not occur when exposed to 0.1 and 0.05 micromol g(-1) at 14 and 28 days, respectively, whereas NRRTs showed significant reduction from the control, as was readily bioconcentrated in the reduced form of As(III) in earthworms and clear dose-response relationships were found for As body burden and NRRTs. Therefore, it is possible to conclude that As has an adverse effect on lysosomal membrane of coelomocytes, and NRRT assay is a potentially applicable method to assess As toxicity as an early warning tool. Also, sequestered As in the form of As(III)-thiol complex can be expected to cause an adverse effect on lysosomal membrane stability.     

Toxicology and carcinogenesis studies of pentachlorophenol in rats.

Pentachlorophenol (PCP) has been used as an herbicide, algaecide, defoliant, wood preservative, germicide, fungicide, and molluscicide. A 28-day toxicity study of PCP in F344/N rats of both sexes was conducted to select dose levels for a carcinogenicity study. Groups of 10 male and 10 female rats were given 0, 200, 400, 800, 1600, or 3200 ppm PCP in feed for 28 days. The incidences of minimal to mild hepatocyte degeneration in males and females exposed to 400 ppm or greater and the incidences of centrilobular hepatocyte hypertrophy in the 3200-ppm groups were increased. For carcinogenicity studies, groups of 50 male and 50 female F344/N rats were fed diets containing 200, 400, or 600 PCP for 2 years. A stop-exposure group of 60 male and 60 female rats received 1000 ppm of PCP in feed for 52 weeks and control feed thereafter for the remainder of the 2-year studies; 10 male and 10 female rats were evaluated at 7 months. Survival of 600-ppm males was significantly greater than that of the controls; survival of all other exposed groups was similar to that of the control groups. Mean body weights of the 400- and 600-ppm groups were generally less than those of the controls throughout the studies. There was no evidence of carcinogenic activity of PCP in male or female rats fed diets containing 200, 400, or 600 ppm for 2 years. Stop-exposure study males and females regained a transitory body weight reduction by the end of the 2 year study, and males had better survival than the controls. At a 7-month interim evaluation, the incidences of centrilobular hypertrophy in stop-exposure males and females exceeded those in the controls. At 2 years, malignant mesothelioma originating from the tunica vaginalis was present in 9 1000-ppm males and 1 control male (p = 0.014). Nasal squamous cell carcinomas were present in five 1000-ppm males and 1 control male. This incidence was not significantly increased but exceeded the historical control range (0-4%). Based on the increased incidences of mesotheliomas and nasal tumors, there was some evidence of carcinogenic activity of PCP in male rats given a diet containing 1000 ppm for 1 year followed by control diet for 1 year. There was no evidence of PCP carcinogenic activity in stop-exposure female rats.     

Effect of variable versus fixed exposure levels on the toxicity of acetaldehyde in rats

The effects of exposure pattern on the toxicity of acetaldehyde vapour were investigated in 4-week inhalation studies. Male rats were exposed to 500 or 150 and 110 ppm for 6 h per day/5 days per week. One group of animals was exposed without interruption, the exposure of a second group was interrupted for 1.5 h between the first and second 3-h periods, the exposure of a third group was similarly interrupted and for six 5 min periods exposure was increased sixfold. Peak exposures of up to 3000 ppm superimposed on 500 ppm acetaldehyde caused irritation and excitation, and reduced body weight gain. No such effects occurred after interrupted or uninterrupted exposure to 500 ppm acetaldehyde without peak loads. A reduced phagocytotic index of lung macrophages was found in each of the groups exposed to 500 ppm acetaldehyde, the effect being most marked in the group with superimposed peaks of 3000 ppm. Degeneration of the nasal olfactory epithelium was observed in rats uninterruptedly exposed to 500 ppm acetaldehyde. Interruption of the exposure or interruption combined with peak exposure did not visibly influence this adverse effect on the nose. No compound-related effects were seen in rats interruptedly or uninterruptedly exposed to 150 ppm acetaldehyde or interruptedly exposed to 110 ppm with peak loads of 660 ppm. As a consequence 150 ppm acetaldehyde can be considered a 'no-toxic-effect level' in male rats exposed for 6 h/day, 5 days/week, during a 4-week period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Optimization of NRU assay in primary cultures of Eisenia fetida for metal toxicity assessment

Coelomocytes, immunocompetent cells of lumbricids, have received special attention for ecotoxicological studies due to their sensibility to pollutants. Their in vitro responses are commonly quantified after in vivo exposure to real or spiked soils. Alternatively, quantifications of in vitro responses after in vitro exposure are being studied. Within this framework, the present study aimed at optimizing the neutral red uptake (NRU) assay in primary culture of Eisenia fetida coelomocytes for its application in soil toxicity testing. Optimized assay conditions were: earthworm depuration for 24 h before retrieving coelomocytes by electric extrusion; 2 × 10⁵ seeded cells/well (200 µl) for the NRU assay and incubation for 1 h with neutral red dye. Supplementation of the culture medium with serum was not compatible with the NRU assay, but coelomocytes could be maintained with high viability for 3 days in a serum-free medium without replenishment. Thus, primary cultures were used for 24 h in vitro toxicity testing after exposure to different concentrations of Cd, Cu, Ni and Pb (ranging from 0.1 to 100 μg/ml). Primary cultures were sensitive to metals, the viability declining in a dose-dependent manner. The toxicity rank was, from high to low, Pb > Ni > Cd > Cu. Therefore, it can be concluded that the NRU assay in coelomocytes in primary cultures provides a sensitive and prompt response after in vitro exposure to metals.     

Phencyclidine-induced desensitization of striatal dopamine release.

Increased release of dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) from slices of striatum of DBA/2J mouse in response to administration of phencyclidine (PCP) in vitro has been observed to be transient, despite continued exposure to PCP. To determine whether this transient response was a result of depletion of releasable pools, toxicity or an adaptive response (desensitization), the recovery of the response to PCP was evaluated. Slices in the control condition were exposed to PCP (300 microM) during test-exposure only. Slices in the PCP pre-exposure condition, were exposed first to PCP (30 microM; pre-exposure) and subsequently to PCP (300 microM; test-exposure). During a washout period (0, 30, 60 or 120 min) between exposures to PCP, the slices were superfused in the absence of PCP. Pre-exposure to PCP diminished the subsequent response to test-exposure to PCP (49 and 37% of control for DA and DOPAC, respectively) after 0 min washout. Overflow of DA evoked by PCP returned towards control values but remained decreased (66% of control) after up to 120 min washout. However, overflow of DOPAC did not return to control values after 60 min washout. Thus, the diminished dopaminergic response, resulting from continued exposure to PCP was not due to depletion of the releasable pool or cytotoxicity but rather to a dynamic adaptive response of the dopaminergic neuron to PCP.     

Developmental Toxicity Evaluation of Inhaled Nitrobenzene in CD Rats

Developmental Toxicity Evaluation of Inhaled Nitrobenzene inCD Rats. TYL, R. W., FRANCE, K. A., FISHER, L. C., DODD, D.E., PRITTS, I. M, LYON, J. P., O'NEAL, F. O., and KIMMERLE,G. (1987). Fundam. Appl. Toxicol. 8, 482–492. PregnantCD (Sprague–Dawley) rats were exposed to nitrobenzenevapor (CAS Registry No. 98-95-3) at 0, 1, 10, and 40 ppm (meananalytical values of 0.0, 1.06, 9.8, and 39.4 ppm, respectively)on gestational days (gd) 6 through 15 for 6 hr/day. At sacrificeon gd 21, fetuses were evaluated for external, visceral, andskeletal malformations and variations. Maternal toxicity wasobserved: weight gain was reduced during exposure (gd 6–9and 6–15) to 40 ppm, with full recovery by gd 21, andabsolute and relative spleen weights were increased at 10 and40 ppm. There was no effect of treatment on maternal liver,kidney, or gravid uterine weights, on pre- or postimplantationloss including resorptions or dead fetuses, on sex ratio oflive fetuses, or on fetal body weights (male, female, or total)per litter. There were also no treatment-related effects onthe incidence of fetal malformations or variations. In summary,during organogenesis in CD rats, there was no developmentaltoxicity (including teratogenicity) associated with exposureto nitrobenzene concentrations that produced some maternal toxicity(10 and 40 ppm) or that produced no observable maternal toxicity(1 ppm).     

Phencyclidine during pregnancy: fetal brain levels and neurobehavioral effects

Either phencyclidine (PCP) (5, 10, or 20 mg/kg) or saline was administered SC to pregnant CF-1 mice during either MID (E6-E15) or LATE (E12-E18) gestation. Because of the reported prolonged persistence of PCP in adult tissues we first determined its half-life in fetal brain for both treatment periods. PCP appeared rapidly in fetal tissues after maternal administration but was not detected after 8 hours. Then, other treated and control litters were fostered to untreated controls, growth determined and the ontogeny of isolation-induced aggressive behavior examined. Subteratogenic doses of PCP produced mild maternal toxicity without lethality. There was an apparent selective embryolethal effect on males but PCP did not produce an effect on postnatal growth. Prenatal PCP did not alter the ontogeny or intensity of isolation-induced aggressive behavior in male offspring. The results are discussed in relation to other prenatal studies of PCP toxicity and teratogenicity.     

Percutaneous Absorption of Pentachlorophenol from Soil

Pentachlorophenol (PCP) is one of the most heavily used pesticides.About 80% of PCP is used for wood preservation, whereas theremainder is used as an herbicide, fungicide, and disinfectant.PCP is a probable human carcinogen, based on animal studies.Illness and death have been reported where PCP is in directcontact with skin. PCP is the most ubiquitous compound foundwhen the general population is screened for pesticide residue.PCP is found in soil as well as other environmental sources.Our objective was to determine the skin bioavailability of PCPfrom soil and from the control vehicle acetone. In vivo in theRhesus monkey, percutaneous absorption of PCP was 24.4±6.4%of applied dose from soil and 29.2±5.8% of applied dosefrom acetone vehicle for a 24-hr exposure period. This amountof absorption makes PCP one of the more extensively absorbedcompounds to date. Additionally, the ¹⁴C half-life was 4.5 daysfollowing both intravenous and skin administration of [¹⁴C]PCP.These data suggest high bioavailability and an extended biologicalinteraction period with the long half-life. In vitro percutaneousabsorption with human cadaver skin and human plasma receptorfluid underestimated the in vivo absorption. Receptor fluidaccumulation was 0.6±0.09% and 1.5±0.2% for twoskin sources for PCP in acetone vehicle and 0.01±0.00%and 0.00±0.08% for two skin sources with soil vehicle.Skin content after skin surface wash ranged from 2.6 to 3.7%for acetone vehicle and 0.07–0.11% for soil vehicle. Overallaccountability for in vitro dose ranged from 81 to 96%.     

Evaluation of the Effects of Inhalation Exposure to 1,3-Dichloropropene on Fetal Development in Rats and Rabbits

Evaluation of the Effects of Inhalation Exposure to 1,3-Dichloropropeneon Fetal Development in Rats and Rabbits. HANLEY, T. R., Jr.,JOHN-GREENE, J. A., YOUNG, J. T., CALHOUN, L. L., AND RAO, K.S. (1987). Fundam. Appl. Toxicol. 8, 562–570. 1,3-Dichloropropene(DCP), which has found widespread use as a soil fumigant, wasevaluated for its potential effects on embryonal and fetal developmentin rats and rabbits. Pregnant Fischer 344 rats and New ZealandWhite rabbits were exposed to 0, 20, 60, or 120 ppm of 1,3-dichloropropenefor 6 hr/day during gestation Days 6–15 (rats) or 6–18(rabbits). Exposure-related decreases in maternal weight gainand feed consumption were observed in rats at all treatmentlevels. Decreased weight gain was also observed among rabbitsat 60 and 120 ppm. A slight, but statistically significant,increase in the incidence of delayed ossification of the vertebralcentra in rats exposed in ulero to 120 ppm of DCP was consideredof little toxicologic significance in light of the maternaltoxicity observed at this exposure concentration. No evidenceof a teratogenic or embryotoxic response was observed in eitherspecies at any exposure level tested. Thus, it was concludedthat DCP was not teratogenic at exposure levels up to 120 ppmin either rats or rabbits.     

Subchronic Inhalation of Diethylamine Vapor in Fischer-344 Rats: Organ System Toxicity

Subchronic Inhalation of Diethylamine Vapor in Fischer-344-Rats:Organ System Toxicity. LYNCH, D. W., MOORMAN, W. J., STOBER,P., LEWIS, T. R., AND IVERSON, W. O. (1986). Fwidam. Appl. Toxicol.6, 559–565. Male and female Fischer 344 (F-344) rats wereexposed at 0, 25, or 250 ppm diethylamine (DEA) vapor, 6.5 hrper day, 5 days per week, for 24 weeks in order to assess cardiacand other organ system toxicity. Scheduled sacrifices were performedfollowing 30, 60, and 120 days of exposure. During the first2 weeks of exposure, the rats exposed at 250 ppm DEA did notgain weight. After 2 weeks, however, the rate of weight gainof these rats was greater than that of controls. Nevertheless,mean body weights for both sexes of rats exposed at 250 ppmDEA remained depressed compared to controls throughout the study.Sneezing, tearing, and reddened noses were seen in rats exposedat 250 ppm DEA. Histopathologic examinations revealed lesionsof the nasal mucosa of rats exposed at 250 ppm DEA (rats exposedat 25 ppm were not evaluated). These lesions of the respiratoryepithelium consisted of squamous metaplasia, suppurative rhinitis,and lymphoid hyperplasia. There were no pronounced treatment-relatedeffects on organ weights, hematology, or clinical chemistryindices except for blood urea nitrogen which was elevated inrats of both sexes exposed at 250 ppm DEA for 24 weeks. In contrastto the highdose animals, no treatment-related effects were observedin rats intermittently exposed at 250 ppm DEA for up to 24 weeks.No evidence of cardiotoxicity was seen in rats exposed to eitherDEA concentration for up to 24 weeks.     

Pulmonary Alterations in Rats Due to Acute Phosgene Inhalation

Pulmonary Alterations in Rats Due to Acute Phosgene Inhalation.CURRIE, W. D., HATCH, G. E., AND FROSOLONO, M. F. (1987). Fundam.Appl. Toxicol. 8, 107–114. This study evaluated the relationshipbetween low-level phosgene (COCl₂) exposure and pulmonary changeor damage. Male Sprague–Dawley rats were exposed to phosgenefor 4 hr at concentrations of 0.125 to 1.0 ppm (30,60, 120,and 240 ppm.min). We examined the dose-related changes in bodyweight, lung wet and dry weights, lavage fluid protein concentrations(LFP), total cell count, and cell differential in rats exposedto phosgene under carefully controlled conditions. These parameterswere measured at the conclusion of single acute exposures andfor 3 days postexposure. Significant changes in lung weights(wet and dry) were observed following exposure to 120 and 240ppm.min phosgene and the LFP was significantly altered at 60ppm.min. The changes in lung wet and dry weights pooled overall times and phosgene concentrations each correlated significantlywith the change in LFP induced by phosgene. The total numberof cells in the lavage fluid of phosgene-exposed rats was increased,and the most sensitive cellular indicator of phosgene inhalationwas the increase in the percentage of polymorphonuclear leukocytes(PMNs). These results confirm that LFP concentration and cellulardifferentials can be used as an index of lung damage due tophosgene. A dose-response relationship for the measured parameterswas observed. Over the dosage range studied, the return of allmeasured parameters to near control levels within 3 days followingexposure showed that the pulmonary damage was reversible orrapidly reparable. Although the acute effects were shown tobe reversible, studies on chronic, low-level phosgene exposuresare necessary to determine safe levels for industrial employees.     

Extrapolation of the laboratory-based OECD earthworm toxicity test to metal-contaminated field sites

The effects of cadmium, copper, lead and zinc on survival, growth, cocoon production and cocoon viability of the earthworm Eisenia fetida (Savigny) were determined in three experiments. In experiment 1, worms were exposed to single metals in standard artificial soil. For experiment 2, worms were maintained in contaminated soils collected from sites at different distances from a smelting works situated at Avonmouth, south-west England. In experiment 3, worms were exposed to mixtures of metals in artificial soil at the same concentrations as those present in the field soils. A survey of earthworm populations was carried out also. Population densities and species diversities of earthworms declined with proximity to the smelting works. No earthworms were found within 1 km of the factory. Comparison of toxicity values for the metals determined in the experiments indicated that zinc is most likely to be limiting earthworm populations in the vicinity of the works. Zinc was at least ten times more toxic to E. fetida in artificial soil than in contaminated soils collected from the field. This difference was probably due to the greater bioavailability of zinc in the artificial soil. The results are discussed in the context of setting protection levels for metals in soils based on laboratory toxicity data.     

In vitro penetration of soil-aged mercury through pig skin

The dermal bioavailability of mercury "aged" in soil for 3 mo was compared to that of pure mercury (without soil) and to mercury in brief contact with soil (16 h). Studies were conducted in vitro with [203Hg]mercuric chloride on dermatomed male pig skin by flow-through diffusion cell methodology. Less than 0.5% of the initial mercury dose penetrated through skin into receptor fluid after each treatment. The majority of pure mercury became covalently bound to skin. However, a short contact time with either an Atsion (sandy) or Keyport (clay) soil significantly decreased the total penetration of mercury (sum of receptor fluid and skin) by 40%. After aging, a 95% reduction in total penetration was observed for the compound relative to chemical without soil. Both soils bind mercury more strongly with time, as evidenced by larger quantities of radioactivity in soil and smaller amounts in skin decontaminate after aging than in soil for 16 h. Decreased mercury bioavailability with aging indicates lower health risk and reduced need for soil cleanup.