-
01/2011: pages 81-94; , ISBN: 978-0-8412-2679-1
-
[show abstract]
[hide abstract]
ABSTRACT: Risk assessment of man-made chemicals such as pesticides are mainly focused on parent compounds, and relatively little is known about their metabolites, especially with regard to target organ damages such as immunotoxicity. In the present study, the immunotoxicity of five synthetic pyrethroids (SPs) and three common metabolites was evaluated using an in vitro model by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cytoflow, and enzyme-linked immunosorbent assay (ELISA). Cell viability and apoptosis assays showed that both SPs and their metabolites possessed cytotoxicity to the monocytic cells. The aldehyde and acid derivatives were more effective than the other compounds at cytotoxicity, with inhibition of cell viability by 56.8 and 50.6% at 10⁻⁵ mol L⁻¹, and induction of 8.52 and 8.81% cell apoptosis, respectively. Exposure to SPs and their metabolites also led to changes in the secretion levels of tumor necrosis factor α (TNF α) and interleukins (ILs), and again the metabolites showed stronger effects than the parent compounds. The aldehyde derivative upregulated IL-12p70 level by 1.87-fold, and the alcohol and acid derivative increased the secretion of TNF α 5.88 and 7.96-fold, relative to the control group. In the in vitro model, the common metabolites of SPs clearly exerted greater immunotoxic effects to monocytes than the intact parent compounds. Results from the present study suggested the need for considering metabolites in achieving more comprehensive health risk assessment of man-made chemicals, including target organ toxicities such as immunotoxicity.
Environmental Toxicology and Chemistry 11/2010; 29(11):2505-10. · 2.81 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bifenthrin (BF) is a synthetic pyrethroid that targets the nervous system of insects and may have adverse effects on the behavior and development of nontarget organisms. However, no reports have been issued on the effects of different enantiomers on locomotor behavior for synthetic pyrethroids (SPs) in zebrafish, and whether locomotor activity is associated with the developmental toxicities remains unclear. In this study, enantioselectivity of BF (1S and 1R) on the acute locomotor activity and developmental toxicities of embryonic-larval zebrafish were first evaluated. The results indicated that 1R-BF was more toxic, causing morphological impairments, with a 96-h median effective concentration (EC50) of 226 microg/L for pericardial edema and 145 microg/L for curved body axis. Administration of 20 microg/L of one enantiomer of BF had differential effects on the locomotor activity of zebrafish larvae at 4 d postfertilization (dpf) under alternating light and dark conditions. Larvae treated with 1R-BF were not sensitive to the alteration of light to dark, and the locomotor activities were reduced to a level similar to that observed in light, which otherwise increased rapidly and markedly. However, 1S-BF did not alter the general pattern of zebrafish response to the light or dark compared with the control. The results demonstrated that the differential effects on development might have contributed to the enantioselectivity in the locomotor activity. The consistency of enantioselectivity with insecticidal activity may also indicate a common mode of action. Furthermore, 1R-BF accelerated the spontaneous movement and hatching process, whereas 1S-BF seemed to be inhibitory. The results suggest the need to link behavioral changes to developmental toxicities in order to achieve more comprehensive health risk assessments of chiral pesticides.
Environmental Toxicology and Chemistry 07/2010; 29(7):1561-7. · 2.81 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Synthetic pyrethroids (SPs) are among the most common pesticides in current use, and so far, several SPs have been assessed for their potential estrogenicities by various methods. Previous studies have shown that the estrogenicities partly come from their metabolites. Although considerable information is available with respect to the metabolism and environmental degradation of SPs, little is known about the estrogenicities of the metabolites. In this study, permethrin (PM) and beta-cypermethrin (CP), as well as their metabolites (3-phenoxybenzoic alcohol (PBCOH), 3-phenoxybenzaldehyde (PBCHO) and 3-phenoxybenzoic acid (PBCOOH) were evaluated for their estrogenic activities in the MCF-7 human breast carcinoma cell line. In the MCF-7 cell proliferation assay, PM and CP exhibited significant estrogenic activities at 10(-7) mol/L, comparable to 17beta-estradiol (E2) of 10(-9) mol/L, with the relative proliferative effect ratios of 55.4% and 56.3%, respectively. The real-time quantitative polymerase chain reaction (qRT-PCR) results confirmed the estrogenicities of PM and CP with significant alteration of pS2 and ERalpha mRNA levels observed at 10(-6) mol/L. For the three major metabolites, PBCOH and PBCOOH exhibited estrogenic activities in all assays, while no significant estrogenic responses was observed for PBCHO compared to the vehicle control. In particular, PBCOH had even slightly stronger estrogenic activity than its parent compounds, indicating that metabolism may be one of the reasons for the estrogenicities of the SPs. Given the widespread use of SPs, the toxicological effects of parent compounds and their metabolites should be taken into consideration in the risk assessment of SPs.
Journal of Environmental Sciences 01/2010; 22(2):290-6. · 1.66 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bifenthrin (BF) is widely used as a miticide in orchards, nurseries and homes due to its great photostability and insecticidal activity. Recently, extensive research has been conducted on the toxicity of BF in in vitro and in vivo assays. However, no data is so far available regarding the developmental toxicity of BF to fish in early life stages. In this study, the developmental effects of BF were evaluated in embryo-larval zebrafish. At specified stages (24, 48, 72, and 96hpf), spontaneous movement, survival and hatching as well as non-lethal malformation like curved body axis or edema were described in detail. No significant lethal effects of the treatment group compared to the control occurred except for the highest concentration group exposed for 96h. The hatching process was accelerated by BF in a concentration-dependent way, correlated with increasing spontaneous movement. Developmental abnormalities were observed for the test compound with 96-h EC(50) of 256microgL(-1) for pericardial edema, and 109microgL(-1) for curved body axis. Results from locomotor assays showed that zebrafish larvae of 96hpf exhibited impaired swimming behaviour after exposure to 50, 100, and 200microgL(-1) from 3 to 84hpf. After being cultured in the BF-free embryo medium for one more day till 120hpf, larvae from the 50microgL(-1)group seemed to have recovered and showed no difference in the swimming behaviour compared to the control while animals of the two higher concentration groups were exhausted and swam in significantly lower speed. Furthermore, reverse transcription real-time PCR results showed that vitellogenin I expressions were significantly induced in larval zebrafish exposed to 150microgL(-1) BF for 72h, indicating the disruption of the endocrine level. In summary, our studies showed that BF was developmentally toxic to zebrafish in early life stage after short-term exposure to sublethal concentrations and had the ability to impair the individual behaviours which are of great importance in the assessment of their ecological fitness.
Aquatic toxicology (Amsterdam, Netherlands) 10/2009; 95(4):347-54. · 3.12 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Chirality exists extensively in nature. Synthetic chiral plant growth regulators and other pesticides usually behave enantioselectively in phyto-biochemical processes. Chiral plant growth regulators regulate the physiological processes of plants enantioselectively, and chiral pesticides cause enantioselective toxicities or ecotoxicities to plants. On the other hand, these chiral agrochemicals can be absorbed and enantioselectively metabolized by plants. This review summarizes the enantioselective effects of chiral plant growth regulators on plants and the phytotoxic and biotransformation effects of chiral herbicides and several persistent organic pollutants (POPs) on plants. Together, this information on the interactions between chiral agrochemicals and plants might shed light on studies on the chemical and biological behaviors of chiral chemicals, and direct research into the selection of plants, which can potentially decontaminate the environment.
Journal of Agricultural and Food Chemistry 04/2009; 57(6):2087-95. · 2.82 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Enantioseletive toxicities of chiral pesticides have become an environmental concern recently. In this study, we evaluated the enantiomeric separation of salithion on a suite of commercial chiral columns and assessed the toxicity of enantiomers toward butyrylcholinesterase and Daphnia magna. Satisfactory separations of salithion enantiomers could be achieved on all tested columns, that is, Chiralcel OD, Chiralcel OJ, and Chiralpak AD column. However, the Chiralpak AD column offered the best separation and was chosen to prepare micro-scale of pure salithion enantiomers for subsequent bioassays. The first and second enantiomers eluted on the Chiralpak AD column were further confirmed to be (-)-S-salithion and (+)-R-salithion, respectively. The half inhibition concentrations to butyrylcholinesterase of racemate, (+)-R-salithion, and (-)-S-salithion were 33.09, 2.92, and 15.60 mg/l, respectively, showing (+)-R-enantiomer being about 5.0 times more potent than its (-)-S-form. However, the median lethal concentrations (96 h) of racemate, (+)-R-salithion, and (-)-S-salithion toward D. magna were 3.54, 1.10, and 0.36 microg/l, respectively, suggesting that (-)-S-salithion was about 3.0 times more toxic than (+)-R-form. Racemic salithion was less toxic than either of the enantiomers in both bioassays, suggesting that antagonistic interactions might occur between the enantiomers during the toxication action. This work reveals that the toxicity of salithion toward butyrylcholinesterase and D. magna is enantioselective, and this factor should be taken into consideration in the environmental risk assessment of salithion.
Chirality 02/2009; 21(10):922-8. · 2.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Information on the effects of pesticide degradation on aquatic organisms is needed to properly evaluate the ecotoxicity arising from the use of pesticides and for aquatic risk assessment. This work evaluated the toxicity of diclofop-methyl (DM) and its two major metabolites, diclofop (DC) and 4-(2,4-dichlorophenoxy)-phenol (DP), to three freshwater microalgae, Chlorella pyrenoidosa, Chlorella vulgaris, and Scenedesmus obliquus. The degradation of DM in the algal suspensions was determined. Diclofop-methyl was rapidly absorbed into the cells of the tested algae, in which it was hydrolyzed to DC and further degraded to DP. The half-lives derived from the first-order kinetics indicated that DP (t1/2 = 2.47-5.80/d) degraded faster than DC (t1/2 = 6.24-12.25/d). The 4-(2,4-dichlorophenoxy)-phenol was the strongest inhibitor of algal growth, followed by DM and DC, as indicated by their EC50 values of 0.17 to 0.25, 0.42 to 2.23, and 4.76 to 8.89 mg/L, respectively. The evaluation of overall DM toxicity to tested algae in the aquatic systems thus needs to take into consideration the degradation of DM. A positive relationship appears to exist between the toxicity of DM and DC and their degradability in algal suspensions. Such a relationship, if confirmed using more pesticides and aquatic organisms, would improve the quality and efficiency of the aquatic risk assessment and management associated with pesticide use.
Environmental Toxicology and Chemistry 06/2007; 26(5):970-5. · 2.81 Impact Factor
