摘要:

Composting is being explored as a means to remediate 2,4,6-trinitrotoluene (TNT) contaminated soils. This process appears to modify TNT and to bind it to organic matter. The health hazards associated with dusts generated from such materials cannot be predicted without knowing if the association between TNT residues and compost particulate is stable in biological systems. To address this question, single doses of [l4C]-TNT, soil spiked with [14C]-TNT, or compost generated with [l4C]-TNT-spiked soils were administered to rats by intratracheal instillation. The appearance of 14C in urine and tissues was taken as an indication of the bioavailability of TNT residues from compost particles. In rats instilled with neat [14C]-TNT, about 35% of the UC dose appeared in urine within 3 d. Thel4C excreted in urine by these rats decreased rapidly thereafter, and was undetectable by 4 wk after treatment. Similar results were obtained with soil-treated rats. In contrast, after treatment with [14C]-TNT-labeled compost, only 2.3% of the total 14C dose appeared in urine during the first 3 d. Low levels of14C continued to be excreted in urine from compost-treated rats for more than 6 mo, and the total amount of HC in urine was comparable to that in TNT-treated animals. Determination of the radiolabel in tissues showed that MC accumulated in the kidneys of rats treated with labeled compost but not in rats treated with [l4C]-TNT or [14C]-TNT-spiked soil. These results indicate that the association between TNT and particulate matter in compost is not stable when introduced into the lungs. Accumulation of 14C in kidneys suggests the presence of a unique TNT residue in compost-treated rats. The rate of excretion and tissue disposition of UC in rats treated with TNT-spiked soil indicate that TNT in soil is freely available in the lungs.

ISSN:0098-4108    

DOI:10.1080/00984109708984014

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The public is continually faced with making decisions about the risks associated with envi ronmental hazards, and, along with managers and government officials, must make informed decisions concerning possible regulation, mitigation, and restoration of degraded sites or other environmental threats. We explored the attitudes regarding several environ mental hazards of six groups of people: undergraduate science majors, undergraduate nonscience majors, and graduate students in environmental health, in ecological risk assessment, and in nonscience disciplines, as well as nonstudents over 35 yr of age. We had predicted that there would be significant differences in attitudes between science and nonscience majors and as a function of age. Relative concerns could be divided into three discrete classes (in descending order of concern): (I) general ecological problems (cutting tropical forests, polluting groundwater, trash along the coasts, lead in drinking water, and acid rain), (2) radon and nuclear wastes, and finally (3) specific nuclear waste facilities, chromium, fertilizers and pesticides, and electromagnetic waves. For any hazard, attitudes were consistent across groups with regard to ranking the severity of the environmental problem and willingness to expend funds to solve the problems. Attitudes about spending money to develop methods to evaluate risk fell in the middle level of concern. There were no major differences among classes of college-age students, or between them and older nonstudents.

ISSN:0098-4108    

DOI:10.1080/00984109708984015

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

It seems evident from a wealth of scientific research that mercury is toxic. Because of the nature of the Saudi markets, different brands of skin-lightening creams are widely avail able. In this study, 38 skin-lightening cream samples were collected and analyzed for mer cury by inductively coupled plasma spectrometry after an acid digestion procedure. About 45% of the tested skin-lightening cream samples contained mercury at levels well above the FDA's acceptable limit of 1 ppm. These findings are alarming and have wide legal and educational implications for Saudi Arabia in particular and developing countries in general. Further investigation for possible adverse health effects is also needed.

ISSN:0098-4108    

DOI:10.1080/00984109708984016

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Induction of cytochrome P-4501A protein and induction of related enzyme activity are hallmark physiological responses following exposure to planar halogenated aromatic hydro carbons (HAHs) such as 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126; PeCB). Environments contaminated by HAHs are often contaminated by mixtures of anthropogenic contami nants, including organometallic compounds. Both HAHs and organometallics easily bio-concentrate and bioaccumulate in aquatic food chains that may ultimately be linked to humans through seafood consumption. Tributyltin (TBI), a marine biocide, has been detected in many aquatic environments due to its primary use as a marine antifoulant agent. Exposure to TBI, as well as several PCBs, has been associated with immunotoxicity, neurotoxicity, and endocrine disruption. Recently TBT has been shown to inhibit cyto chrome P-4501A activity in vitro, but information concerning these effects in vivo and in combination with classical inducers of P-4501A, such PeCB, is lacking. We exposed female B6C3F1 mice to 0.01, 0.1, and 1.0 mg/kg PeCB, TBI, or both in combination, with corn oil (CO) serving as a carrier control. Cytochrome P-4501A protein levels and related benzolalpyrene hydroxylation (BaP-OHase) activity were measured following a sin gle acute intraperitoneal dp) dose or seven daily injections. Body, thymus, and liver weights were used to monitor general physiological responses following exposure. P-4501A levels and BaP-OHase activity were significantly elevated in mice exposed to PeCB alone. This effect was enhanced by coexposure to low levels of TBT; PeCB-induced P-4501A-related activity was potentiated at the low range of each. The highest dose of TBT, however, inhibited these activities when given in combination with PeCB. Thymic atrophy was evident only in mice exposed daily to 0.1 and 1.0 mg/kg PeCB alone, or to a combi nation of the lowest and highest dose of PeCB and TBT, respectively. Because environ mental levels of TBT are not expected to be as high as the highest level used in our toxi-cological studies, we conclude that environmental exposure to TBT may potentiate, rather than inhibit, the activity of environmental levels of HAHs that are associated with P-4501A induction.

ISSN:0098-4108    

DOI:10.1080/00984109708984017

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Activity of nonspecific esterase from different tissues (i.e., liver, gallbladder, heart, intestine, and muscle) of five species of freshwater fish, namely, topmouth gudgeon (Pseudorasbora parva), goldfish (Carassius auratus), nile tilapia (Tilapia nilotica), mosquitofish (Gambusia affinis), and rainbow trout (Salmo gairdneri) was tested using α-naphthyl acetate as sub strate. The results indicated that activity of the enzyme was mainly concentrated in the digestive system (i.e., intestine, liver, bile). The overall activity was highest in nile tilapia, followed by mosquitofish, topmouth gudgeon, goldfish, and lowest in rainbow trout. Electrophoresis and the following in vitro treatment of the isoenzymes with triphenol phos phate (TPP, an inhibitor of carboxylesterase) indicated the TPP-sensitive esterase was mainly distributed in liver of the five species. The enzyme was not found in the other five tissues (including gill) except in gallbladder of topmouth gudgeon and goldfish. The corre lation was obviously improved between susceptibility and detoxification capacity if activity of the TPP-sensitive esterase was employed instead of that of the nonspecific esterase to make the comparison. In vitro treatment of nonspecific esterase in liver with malaoxon proved that the active metabolite of malathion inhibited a different isoenzyme from the TPP-sensitive one.

ISSN:0098-4108    

DOI:10.1080/00984109708984018

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

In the present study, the effects of malathion and malathion derivatives on histamine and β-hexosaminidase release by RBL-1 cells, rat peritoneal mast cells (RPMC), and human peripheral blood basophils (HPBB) and cutaneous mast calls were examined. One hour of incubation of RBL-1 cells with all organophosphate compounds tested, except for malathion and malathion monoacid, led to an increase in histamine release. β-Hexosamini dase, an enzyme released by basophilic cells and a biochemical marker of degranulation, was not released from RBL-1 cells after 1 h of exposure to organophosphate compounds. Within 4 h, all compounds tested increased the release of histamine and β-hexosamini dase. Longer exposures led to a decrease in the concentration of the compound that was required to cause mediator release. Exposure of RPMC to organophosphate compounds, with the exception of malathion monoacid and malathion (30 min) or malathion mono acid (1 h), led to the release of histamine, but not β-hexosaminidase. Incubation of HPBB with malaoxon (51.4 ± 2.8% total histamine released), malathion diacid (25.7 ± 2.9%), β-malathion monoacid (31.4 ± 2.8%), and isomalathion (57.1 ± 17.1%) for 1 h led to the release of histamine. Only malaoxon and isomalathion caused ^-hexosaminidase release from HPBB after a 1-h incubation. Incubation of cutaneous mast cells with mala oxon and fi-monoacid for 4 h led to increased release of histamine and β-hexosaminidase at levels comparable to compound 48/80. These data suggest that malathion metabolites can cause rapid release of histamine from basophilic cells from a variety of origins and species. With prolonged incubation, malathion itself caused the release of mast-cell media tors, suggesting that the cells may be capable of metabolizing malathion. These data also indicate a disparity between the release kinetics of two different mast-cell mediators con tained in granules by organophosphates, and that there are different mechanisms of medi ator release.

ISSN:0098-4108    

DOI:10.1080/00984109708984019

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Styrene is known to cause both hepatotoxicity and pneumotoxicity in mice. Strain differ ences have been reported by other investigators suggesting that Swiss mice are less suscep tible than non-Swiss mice to styrene-induced liver damage. In this study, A/I and C57BL/6 mice were found to be similar to non-Swiss albino (NSA) mice in susceptibility whereas CD-1 (Swiss) mice were more resistant to hepatotoxicity as assessed by serum sorbitol de hydrogenase levels and pneumotoxicity as determined by gamma-glutamyltranspeptidase and lactate dehydrogenase measurements in bronchoalveolar lavage fluid. Styrene was hepatotoxic in CD-I mice treated with pyridine to induce CYP2E1. CYP2EI apoprotein levels and p-nitrophenol hydroxylase activities in control and pyridine-induced mice were similar in the two strains. Hepatic and pulmonary microsomal preparations from both strains metabolized styrene to styrene oxide at similar rates. CD-1 mice were as susceptible as the NSA mice to the effects of styrene oxide. The data suggest that there are no differ ences in the bioactivation of styrene to styrene oxide or innate susceptibility to the active metabolite that would account for the differences between the CD-1 and NSA mice.

ISSN:0098-4108    

DOI:10.1080/00984109708984020

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We investigated the effect of intratracheally instilled coal fly ash (FA) and copper smelter dust (CU) on the lung integrity and on the ex vivo release of tumor necrosis factor alpha (TNF-α) by alveolar phagocytes. Croups of female NMRI mice received a single intratra cheal administration of different particles normalized for the arsenic content (20 μg/kg body weight, i.e., 600 ng arsenic/mouse) and the particle load (100 mg/kg body weight, i.e., 3 mg/mouse). Mice received tungsten carbide (WC) alone (100 mg/kg), FA alone (100 mg/kg, i.e., 20 μg arsenic/kg), CU mixed with WC (CU, 13.6 mg/kg, i.e., 20 μg arsenic/kg; WC, 86.4 mg/kg) and Ca3(AsO4)2mixed with WC (20 μg arsenic/kg; WC, 100 mg/kg). Animals were sacrificed at 1, 6, or 30 d posttreatment and analyzed by bronchoalveolar lavage for total protein (TP) content, inflammatory cell number and type, and TNF-α production. Additional mice were studied to evaluate particle retention by measuring total arsenic retention in the lung at appropriate times. Instillation of WC induced a mild and transient (d 1) inflammatory reaction characterized by an increase of TP and an influx of polymorphonuclear leukocytes in the alveolar compartment. Compared to WC, Ca3(AsO4)2produced a significant increase of TP content in BALF. CU particles caused a severe but transient inflammatory reaction, while a persisting alveolitis (30 d) was observed after treatment with FA. Compared to control saline, a marked inhi bition of TNF-α release was observed in response to LPS in all groups at d 1. Cytokine production was upregulated in WC- and Ca3(AsO4)2-treated animals after 6 and 30 d, respectively. However, a 90% inhibition of TNF-α production was still observed at d 30 after administration of CU and FA. Although arsenic was cleared from the lung tissue 6 d after Ca3(As04)2administration, a significant fraction persisted (10-15% of the arsenic administered) in the lung of CU- and FA-treated mice at d 30. We hypothetize that sup pression of TNF-α production is dependent upon the slow elimination of the particles and their metal content from the lung.

ISSN:0098-4108    

DOI:10.1080/00984109708984021

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor