Acute toxicity of alpha-cypermethrin to guppy (Poecilia reticulata, Pallas, 1859)

Alpha-cypermethrin is a synthetic pyrethroid insecticide used to control pests in domestic, industrial and agricultural situations. Adult male guppy fish (Poecilia reticulata standard test species) were selected for the bioassay experiments. The experiments were performed in four series and the 96-h LC50 value was determined for guppies. The acute toxicity experiments were carried out by static method and behavioral changes in guppies were determined for each alpha-cypermethrin (98% technical grade) concentration. Data obtained from the alpha-cypermethrin investigation were evaluated by the use of probit analysis statistical method and the 96-h LC50 value for guppy was estimated as 9.43 microg/l.     

Movement and deposition of two organophosphorus pesticides within a residence after interior and exterior applications

Post-application temporal and spatial distributions of two organophosphorus pesticides, diazinon (O,O-diethyl O-[6-methyl-2-(1-methylethyl)-4-pyrimidinyl] phosphorothioate, CAS No. 333-41-5) and chlorpyrifos [O,O-diethyl-O-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphorothioate, CAS No. 2921-88-2], were monitored after homeowner applications for indoor and outdoor insect control. Samples of indoor air, vacuumable carpet dust, carpet dislodgeable residues, deposits on bare floors, table tops and dinnerware, surrogate food, and residues on children's hands and toys were taken before and up to 12 days after treatments in the family room, kitchen, and child's bedroom. Results from the study demonstrate the nature and magnitude of translocation of pesticides from the areas of application to surfaces accessible for human contact and permit comparisons of potential exposures via respiration and dermal contact/oral ingestion. Potential indoor inhalation exposures were estimated to be as high as 0.5 microg/kg/day for diazinon applied indoors and 0.05 microg/kg/day for chlorpyrifos applied to the outside perimeter of the house. While ingestion of carpet dust at the rate of 100 microg/day would have added a maximum of only approximately 0.01 microg/kg/day to the daily dose, residues found on the children's hands suggest that repeated mouthing could have contributed as much as 1-1.5 microg/kg/day. These estimates are below the U.S. Environmental Protection Agency (EPA) reference dose for chlorpyrifos, but exceed those for diazinon.     

Assessment of insecticide contamination in runoff and stream water of small agricultural streams in the main soybean area of Argentina

The first- and second-order streams, Brown and Horqueta, respectively, which are located in the main area of soybean production in Argentina were examined for insecticide contamination caused by runoff from nearby soybean fields. The insecticides most widely used in Argentina (chlorpyrifos, cypermethrin and endosulfan) were detected in sediments, suspended particles and water. Highest concentrations in suspended particles were 318 microg/kg for endosulfan in the stream Horqueta, while 226 microg/kg chlorpyrifos and 13.2 microg/kg cypermethrin were measured in the stream Brown. In the Horqueta stream 150 and 53 microg/kg chlorpyrifos and cypermethrin were detected in runoff sediments, respectively. Whereas cypermethrin concentrations in the suspended particles were relatively low, levels in the floodwater of Brown reached 0.7 microg/l. The highest chlorpyrifos concentration in floodwater was 0.45 microg/l in Brown. However, endosulfan was not detected in the water phase. In runoff water the highest concentrations measured were 0.3 microg/l for chlorpyrifos in Horqueta and 0.49 microg/l for cypermethrin in the Brown stream. On five sampling dates during the pesticide application period in Brown stream (2002/2003) the concentration of chlorpyrifos and cypermethrin in runoff and/or floodwater exceeded the water quality criteria for freshwater mentioned in this study. In three cases this insecticide concentration was measured in stream water, indicating an acute risk to aquatic life. The acute toxicity-exposure-ratio (TER) for chlorpyrifos and cypermethrin also shows an acute risk for aquatic invertebrates in the Brown stream. In the Horqueta chlorpyrifos concentrations in the runoff exceeded the safety levels three times during the application period (2001/2002), potentially endangering the aquatic fauna. Effects on aquatic macroinvertebrates after insecticide contamination were reported in earlier studies in Horqueta stream.     

Investigation of acute toxicity of permethrin on guppies Poecilia reticulata

Permethrin, a synthetic pyrethroid pesticide and potential toxic pollutant contaminating aquatic ecosystems, was investigated in the present study for acute toxicity. Guppy fish (Poecilia reticulata) were selected for the bioassay experiments. The experiments were repeated 3 times and the 48-h LC(50) was determined for the guppies. The static test method of acute toxicity test was used. Water temperature was regulated at 20+/-1 degrees C. In addition, behavioral changes at each permethrin concentration were observed for the individual fish. Data obtained from the permethrin acute toxicity tests were evaluated using the probit analysis statistical method. The 48-h LC(50) value for guppy was estimated as 245.7 microg/l. Values in the range of 0.05-97.0 microg/l have been reported for various other fish species.     

Reproductive effects and bioconcentration of 4-nonylphenol in medaka fish (Oryzias latipes)

The objective of this study was to investigate the reproductive success (fertility and fecundity) of medaka (Oryzias latipes) exposed to 4-nonylphenol (4-NP) in water and the viability of their F(1) offspring. In addition, we measured the bioconcentration of 4-NP in eggs. After a 21-d exposure to 100microg/l 4-NP, medaka showed reduced egg production and fertility. Hepatic vitellogenin levels were increased significantly in males treated with 10, 50 and 100microg/l of 4-NP. In the F(1) generations, the hatchability and time to hatching of embryos in the 100microg/l treatment group were adversely affected, and 2-7microg 4-NP/g egg was found in spawned eggs (the bioconcentration factor: 30-100). These results indicate that (1) 4-NP adversely affected the reproduction (fecundity and fertility) of adult medaka, (2) 4-NP accumulated in eggs through maternal transfer and (3) these levels of 4-NP were associated with adverse effects in the F(1) offspring.     

Effects of chlornitrofen, a herbicide, on reproduction of Brachionus urceolaris (Rotatoria) through water and food (Chlorella)

Chronic effects of chlornitrofen (CNP) on the reproduction of Brachionus urceolaris (Rotatoria) were investigated by exposure of individuals to CNP from the egg stage, which had been attached to the adult. The survivors of 12 neonates, which had been exposed to CNP100, 70 or 40 microg liter(-1) decreased to 50% at the age of c. 2, 4 and 6 days, respectively, compared to c. 6.5 days for those exposed to 0, 10 and 20 microg liter(-1) CNP. Release of offspring (mostly two individuals per day) started at two days old. At the peak, four days old, a control female produced 8.1+/-0.9 offspring per day compared with 4.5+/-1.3 (mean+/-SD, n=12) at 40 microg liter(-1). The cumulative numbers of offspring produced by a female were 25.8+/-1.2, 24.2+/-2.9, 22.3+/-3.6 and 13.6+/-3.1 (mean+/-SD, n=12) at control, 10, 20 and 40 microg liter(-1) CNP exposure, respectively. The 50% reproductive impairment concentration was calculated to be 37 microg liter(-1). Growth of neonates was barely detectable at 70 microg liter(-1), and the rapid increase in the effect of CNP from 40 to 70 microg liter(-1) was attributed to an increase in tolerance with growth of the neonates. The effects of CNP on reproduction were also tested by CNP exposure through food (CNP-accumulated Chlorella). The 50% reproductive impairment concentration of CNP in the alga was calculated to be c.60 microg g(-1) (wet weight) by the same method used to assess the dissolved CNP, although the effect of CNP which may have been released from the alga to the water could not be estimated precisely.     

Multi-generational effects of four selected environmental oestrogens on Daphnia magna

The objective of this study was to determine whether vertebrate-type oestrogens have ecotoxicological effects on a crustacean species. The effects of 17beta-oestradiol (E2), diethylstilbestrol (DES), bisphenol A (BPA) and 4-nonylphenol (4-NP) on the freshwater invertebrate Daphnia magna were assessed over first and second generations. The acute EC(50) 48 h, based on immobilisation, for E2, DES, BPA and 4-NP were 2.87 mg/l, 1.55 mg/l, 7.75 mg/l and 0.13 mg/l, respectively. The impact of the test chemicals on moulting frequency was also assessed. The EC(50) 48 h, based on the inhibition of moult number for E2, DES and 4-NP were 2.04 mg/l, 1.87 mg/l and 0.14 mg/l, respectively. BPA was not observed to impact the moulting frequency of D. magna at concentrations tested. In a series of separate studies, the effects of the four selected test compounds on the survival, moulting frequency and reproduction of first and second generational D. magna were assessed over a period of 21 d. Exposure of D. magna to 4-NP decreased the number of offspring produced in both first and second generation testing. DES proved to have no significant (p0.05) inhibition of fecundity in first generation but when second generation daphnids were exposed to DES, a significant (p0.05) reduction in the number of offspring was recorded. When D. magna were exposed to E2 or BPA, no statistically significant (p0.05) inhibition in the number of moults or offspring produced was observed.     

Effects of long-term chlorpyrifos exposure on mortality and reproductive tissues of Banded Gourami (Trichogaster fasciata)

Abstract

This study assessed the long-term toxicity of chlorpyrifos on survival and reproduction of Banded Gourami by using mortality, gonado-somatic index (GSI) and histopathological observations as endpoints. Adult fish were exposed to five different concentrations of chlorpyrifos (0, 15, 50, 150, 500?µg/L) in 15 PVC tanks for 15, 30, 45, 60 and 75?days. Results showed that all male and female fish died after 15?days of 500?µg/L chlorpyrifos exposure. No consistent significant effect was observed for both male and female GSI. Furthermore, results showed dose- and time-dependent histopathological alterations for both ovary and testes. The 60-d No Observed Effect Concentration (NOEC) for most histopathological alterations of Banded Gourami ovary and testes was 50?μg/L, while 60-d NOEC for mortality of both male and female fish was < 15?μg/L. The results show that the long-term exposure to chlorpyrifos not only affect the reproductive tissues of Banded Gourami at exposure concentrations but also cause their mortality. Future studies should evaluate effects at lower concentrations.     

Metabolism of chlorpyrifos in relation to its effect on the availability of some plant nutrients in soil

A laboratory experiment was conducted to study the persistence and metabolism of chlorpyrifos in Gangetic Alluvial soil of West Bengal and also to evaluate their effect on the availability of the major plant nutrients (N, P and K) in soil following the application of chlorpyrifos @ 1 kg (T1), 10 kg (T2) and 100 kg (T3) a.i.ha(-1). The dissipation followed first order kinetics and the calculated half-life (T1/2) values ranged from 20 to 37 days. The primary metabolite of chlorpyrifos, 3,5,6-trichloropyridinol (TCP) was detected from 3rd day after application and was at maximum on 30th day which decreased progressively to non-detectable level (NDL) on 120th day for all the treatment doses. The secondary metabolite 3,5,6-trichloro-2-methoxy pyridine (TMP) was detected on 30th, 15th and 7th day in T1, T2 and T3 doses respectively which decreased to NDL during 90-120th day. ANOVA study revealed significant decrease in the available N and P content in soil treated with chlorpyrifos in comparison to the control set. The inhibitory effect on available N was attributable to TMP and for P it was due to the presence of TCP and TMP rather than chlorpyrifos itself as revealed by the step wise multiple regression technique. In the later stage of incubation, however the average N and P status was recovered significantly at 120 days which might be due to the disappearance of the metabolites. The variation due to time of observations or treatment doses was minimum in case of available K in soil.     

Physical and motor development in male and female rat offspring prenatally exposed to gamma radiation

Abstract

The effects of radiation on physical and motor development of male and female rats exposed to ionizing radiation in utero were studied. Rats were exposed to three different doses of radiation (150 rad, 15 rad and 6.8 rad, considered as high, moderate and low doses of radiation respectively) on the 20th day of prenatal life. Exposure to 150 rad contributed to significantly lower body weights of both male and female rat offspring. Upper jaw tooth eruption was delayed in 150 rad treated male offspring, as well as in 15 rad and 150 rad treated female offspring. Cliff‐avoidance response was delayed in 6.8 rad, 15 rad, and 150 rad treated male offspring; and 150 rad treated female offspring. Lower jaw tooth eruption, eye opening, and crawling were not affected by radiation in male or female animals. Results indicate that radiation affected the developmental parameters of both male and female rat offspring, and sex of the offspring played no role in the magnitude of radiation induced damages.     

Environmental chemicals with known endocrine potential affect yolk protein content in the aquatic insect Chironomus riparius

The use of vitellogenesis as a marker for possible effects of endocrine disrupting agents on insects was tested in the aquatic midge Chironomus riparius. As test substances the synthetic ecdysoid tebufenozide, and the endocrine disruptors bisphenol a and 4-n-nonylphenol were applied in a semi-static manner. The yolk protein contents of freshly emerged (24 h) male and female midges were determined by an ELISA procedure. In males, where always low amounts of immunoreactivity were apparent, yolk concentrations were lowered by 10% after a 80 microg/l tebufenozide treatment, and by 20-25% after exposition to bisphenol a at concentrations of 1, 100, and 3,000 microg/l. 4-n-nonylphenol contamination caused an inverted dose-response curve. At low test concentrations (1.9-30 microg/l) reduced yolk immunoreactivity occurred, while at medium concentrations (120 and 500 microg/l) no significant effects were observable. In the most highly contaminated group (2,000 microg/l) yolk protein immunoreactivity was elevated to 107% of the control. Female yolk protein contents were affected only in the 3,000 microg bisphenol a/l contaminated group, where yolk immunoreactivity was reduced by ca. 10% compared to the control.     

Investigation of acute toxicity of beta-cypermethrin on guppies Poecilia reticulata

Beta-cypermethrin, a synthetic pyrethroid pesticide and potential toxic pollutant, contaminating aquatic ecosystems was investigated in the present study for acute toxicity. Guppy fish (Poecilia reticulata) was selected for the bioassay experiments. The experiments were repeated three times and the 48-h LC50 was determined for the guppies. The static test method of acute toxicity test was used. Water temperature was regulated at 22 +/- 1 degrees C. In addition, behavioral changes at each beta-cypermethrin concentration were observed for the individual fish. Data obtained from the beta-cypermethrin acute toxicity tests were evaluated using the probit analysis statistical method. The 48-h LC50 value for guppy was estimated as 21.4 microg/l.     

Soil dehydrogenase, phosphomonoesterase and arginine deaminase activities in an insecticide treated groundnut (Arachis hypogaea L.) field

Chlorpyrifos (O,O-diethyl O-3,5,6-trichloro-2 pyridyl phosphorothioate) 20 EC and Quinalphos (O,O-diethyl O-quinoxalin-2-yl phosphorothioate) 25 EC, were applied in groundnut (Arachis hypogaea L.) field as seed treatment at 25 ml/kg and soil treatment at 4 l/ha in 1998 and 1999. The residues of these insecticides were monitored during the entire crop season and their effect on the soil enzymes dehydrogenase, phosphomonoesterase and arginine deaminase were studied. Ninety nine percent of chlorpyrifos residues were dissipated within 60 days from seed treated soil and 98% dissipation was observed in soil treated field for the same days. Its half lives in seed treated soil were 8 days and 7 days and in soil treated field were 9.2 days in and 7.5 days in 1998 and 1999 respectively. Dissipation of quinalphos in comparison to chlorpyrifos was slow both in seed treated and soil treated field. Eighty seven percentage to 92% dissipation of quinalphos residues were observed from seed treated soil and 98% residues were dissipated from soil treated field within 75 days. Its half lives in seed treated soil were 20 days and 18 days and in soil treated field, its half lives were 13 days and 17 days 1998 and 1999 respectively. Inhibition in dehydrogenase activity followed by recovery was observed both in seed and soil treatments with chlorpyrifos. An inhibition of 17.2% was estimated after 60 days of seed treatment in comparison to control. Dehydrogenase activity was significantly reduced to 63% after 15 days of quinalphos seed treatment in comparison to control in 1998. Similar trends were observed in 1999. A significant inhibition in dehydrogenase activity was observed after soil treatment both in 1998 and 1999. Phosphomonoesterase activities were significantly inhibited upto 25.2% as compared to the control, on the 15th day of chlorpyrifos seed treatment in 1998 and similarly, after one day of treatment in 1999. Quinalphos inhibited the phosphomonoesterase activity till the end of the experimental period in the soil treated fields, whereas recovered within 30-60 days of treatment in the seed treated fields. Arginine deaminase activity was significantly stimulated within one day after chlorpyrifos seed and soil treatments in both years. The activity was almost threefold higher on the 30th and the 15th day of soil treatment in 1998 and 1999, respectively. A temporary inhibition of arginine deaminase activity was observed after quinalphos treatment. It was observed that in most of cases insecticides have temporary inhibitory effect on soil enzymes. However, inhibition was smaller in seed treated soil than in direct soil treatment.     

Effects of tributyltin maternal and/or waterborne exposure on the embryonic development of the Manila clam, Ruditapes philippinarum

We examined the effect of tributyltin (TBT) on embryonic development of the Manila clam, Ruditapes philippinarum. In a maternal exposure test, 100 clams were exposed to TBT at measured concentrations of <0.01 (control), 0.061, 0.310, or 0.350 microg/l at 20-22 degrees C for 3 weeks, and the embryo developmental success (the ratio of normal D-larvae to all larvae) was measured. There was a significant negative correlation between embryo developmental success and TBT concentration in the female Manila clams (p < 0.001). These results indicated that TBT accumulated in the female clam decreased embryo developmental success. In a waterborne exposure test, fertilized eggs (4 h after fertilization) were exposed to TBT at measured concentrations of <0.01 (control), 0.062, 0.140, 0.320, or 0.640 microg/l for 23 h. Embryo developmental success was also significantly decreased in all TBT treatment groups compared with that in the control group. TBT accumulated in female adults and waterborne TBT clearly inhibit reproductive success of the clam.     

An assessment of the chronic toxicity of the synthetic pyrethroid, fenvalerate, to Daphnia galeata mendotae, using life tables

The effects of chronic exposure to fenvalerate, a synthetic pyrethroid insecticide, on the cladoceran Daphnia galeata mendotae were evaluated under laboratory conditions. The daphnids were exposed for their entire life cycle to concentrations ranging from 0.005 to 0.1 microg fenvalerate litre(-1). The parameters used to determined toxicity were survival, time to first reproduction, reproductive frequency, number of young per brood, cumulative brood size, intrinsic rate of natural increase (r(m)), generation time (T) and net reproductive rate (R(0)). A concentration of 0.005 microg fenvalerate litre(-1) resulted in an increase in longevity but a decrease in production of young. Higher concentrations caused a decrease in survival. Studies of shorter duration than the complete life cycle of the organisms would not have detected toxicity at such low levels. The intrinsic rate of natural increase, r(m), was not affected by fenvalerate until concentration reached 0.05 microg litre(-1) and r(m) decreased to 0.113 from 0.238. A concentration of 0.01 microg litre(-1) caused the net reproductive rate, R(0), and the generation time, T, to decrease to 73.2 offspring per female and 17.3 days from 125.9 offspring per female and 20.3 days, respectively.     

The interference of 2-chloro-5-oxo-3-hexene diacyl chloride (COHC) in the detection of strong mutagen MX

Laboratory experiments were conducted to examine the impact of cadmium (Cd) on survival of Diplostomum sp. cercariae. Freshly emerged cercariae were exposed to Cd solutions at concentrations ranging between 0.2 and 200 microg/l. The mortality patterns and mean survival times (MSTs) of the exposed parasites were determined by the Kaplan-Meier estimator and were compared (Log-Rank test) to corresponding patterns and estimators of the unexposed controls. Cd concentrations >20 microg/l caused statistically significant changes in the mortality pattern of Diplostomum sp. cercariae and reduced MST by at least five hours compared to the control group, where MST was 52 h. The results show that longevity of the free-living Diplostomum sp. cercariae can be reduced by direct exposure to heavy metals. Cd contamination of aquatic habitats thus potentially can have an impact on parasite populations and communities.     

Determination of pesticides and chronic test with Daphnia magna for rainwater samples

Pesticides contained in rainwater were investigated in June and July 2001 in Yokohama. Although there were few farms and rice paddies near the sampling point, insecticides (fenitrothion and dichlorvos) and fungicides (chlorothalonil and futhalide) were detected by GC-MS and GC-FPD analysis. The maximum concentrations of dichlorvos and fenitrothion were 0.22 microg/L and 0.15 microg/L, respectively. Chronic tests with Daphnia magna were then conducted on two rainwater samples. Test solutions for these chronic tests were prepared by solid-phase extraction. In the case of the rainwater sampled on 25 July, the survival rate of D. magna was 100% after 21 days and no differences were found between the control and sample with regard to the average total number of live offspring produced per parent animal. However, a similar test with rainwater sampled on 14-15 June showed a marked toxic effect, since all the test animals were dead within 2 days. It is concluded that rainwater containing pesticides is an important ecological factor for freshwater plankton.     

Temporal variability in particle-associated pesticide exposure in a temporarily open estuary, Western Cape, South Africa

This study assesses the risk of current-use pesticides in a temporarily open estuary in South Africa by developing probabilistic risk estimates. Particle-associated pesticides (chlorpyrifos, prothiofos, cypermethrin, fenvalerate, endosulfan and p,p-DDE) and physicochemical parameters (salinity, temperature, flow, and total organic content (TOC)) were measured in the Lourens River estuary (Western Cape) twice a month over a period of two years and equilibrium partitioning theory was applied to calculate concentrations of pesticides in the water. The 90th percentile concentrations of pesticides associated to suspended particles and the calculated concentrations in water were 34.0microg kg(-1) and 0.15microg l(-1) for prothiofos, 19.6microg kg(-1) and 0.45microg l(-1) for chlorpyrifos and 18.6microg kg(-1) and 0.16microg l(-1) for endosulfan. Highest average concentrations were found around the summer season due to higher application rates and as a result of the low flow during this season. Species sensitivity distribution indicated a 1.5-2.8 times higher toxicity (hazardous concentration HC5) for marine organisms compared to freshwater organisms. The calculated concentrations in the water exceeded all threshold values suggested by international water guidelines. Chlorpyrifos and endosulfan posed the highest acute risk to the Lourens River estuary. No sufficient toxicity data and threshold values were found for prothiofos.     

Individual and mixture toxicity of three pesticides; atrazine,chlorpyrifos, and chlorothalonil to the marine phytoplankton species Dunaliella tertiolecta

This study analyzed the toxicity of three pesticides (the herbicide atrazine, the insecticide chlorpyrifos and the fungicide chlorothalonil) individually, and in two mixtures (atrazine and chlorpyrifos; atrazine and chlorothalonil) to the marine phytoplankton species Dunaliella tertiolecta (Chlorophyta). A standard 96 h static algal bioassay was used to determine pesticide effects on the population growth rate of D. tertiolecta. Mixture toxicity was assessed using the additive index approach. Atrazine and chlorothalonil concentrations > or = 25 microg/L and 33.3 microg/L, respectively, caused significant decreases in D. tertiolecta population growth rate. At much higher concentrations (> or = 400 microg/L) chlorpyrifos also elicited a significant effect on D. tertiolecta population growth rate, but toxicity would not be expected at typical environmental concentrations. The population growth rate EC50 values determined for D. tertiolecta were 64 microg/L for chlorothalonil, 69 microg/L for atrazine, and 769 microg/L for chlorpyrifos. Atrazine and chlorpyrifos in mixture displayed additive toxicity, whereas atrazine and chlorothalonil in mixture had a synergistic effect. The toxicity of atrazine and chlorothalonil combined was approximately 2 times greater than that of the individual chemicals. Therefore, decreases in phytoplankton populations resulting from pesticide exposure could occur at lower than expected concentrations in aquatic systems where atrazine and chlorothalonil are present in mixture. Detrimental effects on phytoplankton population growth rate could impact nutrient cycling rates and food availability to higher trophic levels. Characterizing the toxicity of chemical mixtures likely to be encountered in the environment may benefit the pesticide registration and regulation process.     

Histological alternation and vitellogenin induction in adult rare minnow (Gobiocypris rarus) after exposure to ethynylestradiol and nonylphenol

Adult rare minnow (Gobiocypris rarus) were exposed to 0, 1, 5, and 25 ng/l (nominal concentrations) of 17alpha-ethynylestradiol (EE2) and 3, 10, and 30 microg/l (nominal concentrations) of 4-nonylphenol (NP) under flow-through conditions for a period of 28 d. Low mortality was observed at 5 and 25 ng/l EE2 and the growth of fish reduced significantly at 25 ng/l EE2 compared to controls. However, the gonadosomatic indices (GSI) of male fish were significantly higher in 1 ng/l EE(2) treatments and in 10 and 30 microg/l NP treatments (p<0.05). Renal somatic indices (RSI) of male fish in EE2 treatments were significantly higher than those in controls (p<0.05). In contrast, significantly decreased GSI and RSI of female fish could only be observed in 5 and 25 ng/l EE(2) treatments (p<0.05). Hepatosomatic indices (HSI) of male fish were significantly higher in 25 ng/l EE(2) treatments. However, significantly increased of HSI of female fish could only be observed in 1 ng/l EE(2) treatments. Plasma vitellogenin (VTG) induction could be observed in males after exposed to different concentrations of EE2 and NP, and plasma VTG concentrations in females exposed to 5 and 25 ng/l EE(2) were also significantly higher than in controls (p<0.05). At level higher than 5 ng/l EE2 or 30 microg/l NP, hepatic tissue and renal tissue impairment of males could be observed. The pathological male liver was associated with a hypertrophy of hepatocytes and damages to cellar structure and accumulated eosinophilic material. Renal tissue showed different pathological effects which was reflected by accumulated eosinophilic material, hemorrhages within the kidney tubules and hypertrophy of the tubular epithelia. Also at these levels of exposure, feminization of male fish could be noticed and parts of males manifested the testis-ova phenomenon. Ovaries of female rare minnow in 25 ng/l EE2 treatment group were degenerated. Therefore when exposed to EE2 and NP even at environmental observed concentrations, adverse effects could occur in the reproductive system of adult fishes. The observed hepatic tissue and renal tissue impairment should be due to the induction and accumulation of VTG in organs, especially in males.