Distribution and Persistence of Tricyaclazole in Agricultural Field Soils

Soil is the major sink for majority of pesticides applied on agricultural crops and its fate depends on variety of factors. There is little research on fate of pesticide in field soil under different climatic conditions and there is a need of study on the influence of climate on pesticide degradation and persistence in soil. In the present study, the persistence and distribution of tricyclazole was investigated in rice field soil under the influence of cold winter condition. Field experiment was carried at 35 different field sites from 6 provinces in Republic of Korea. Limit of detection and limit of quantification of tricyclazole were found to be 0.005 and 0.0165?mg/kg, respectively. The concentrations of tricyclazole in soil samples ranged from 0.387?mg/kg in sites in Gyeongsangbuk-do areas and lowest 0.021?mg/kg in sites from Chuncheongnam-do areas. In natural environmental conditions, tricyclazole persisted longer than 11?months post application in agricultural field soils. Our result indicates the influence of cold climatic condition on the persistence of tricyclazole.     

Association of Cryptosporidium with bovine faecal particles and implications for risk reduction by settling within water supply reservoirs

Artificial cow pats were seeded with Cryptosporidium oocysts and subjected to a simulated rainfall event. The runoff from the faecal pat was collected and different particle size fractions were collected within settling columns by exploiting the size-dependent settling velocities. Particle size and Cryptosporidium concentration distribution at 10 cm below the surface was measured at regular intervals over 24 h. Initially a large proportion of the total volume of particles belonged to the larger size classes (> 17 microm). However, throughout the course of the experiment, there was a sequential loss of the larger size classes from the sampling depth and a predominance of smaller particles (< 17 microm). The Cryptosporidium concentration at 10 cm depth did not change throughout the experiment. In the second experiment samples were taken from different depths within the settling column. Initially 26% of particles were in the size range 124-492 microm. However, as these large particles settled there was an enrichment at 30 cm after one hour (36.5-49.3%). There was a concomitant enrichment of smaller particles near the surface after 1 h and 24 h. For Pat 1 there was no difference in Cryptosporidium concentration with depth after 1 h and 24 h. In Pat 2 there was a difference in concentration between the surface and 30 cm after 24 h. However, this could be explained by the settling velocity of a single oocyst. The results suggested that oocysts are not associated with large particles, but exist in faecal runoff as single oocysts and hence have a low (0.1 m(d-1)) settling velocity. The implications of this low settling velocity on Cryptosporidium risk reduction within water supply reservoirs was investigated through the application of a three-dimensional model of oocyst fate and transport to a moderately sized reservoir (26 GL). The model indicated that the role of settling on oocyst concentration reduction within the water column is between one and three orders of magnitude less than that caused by advection and dilution, depending on the strength of hydrodynamic forcing.     

Azinphosmethyl and fenvalerate washoff from cotton plants as a function of time between application and initial rainfall

Understanding pesticide foliar washoff is important in pest management, in development of integrated management systems, and in environmental modeling. This study was conducted to determine the effect of elapsed time between spray application and initial rainfall on insecticide washoff from foliage. Azinphosmethyl and fenvalerate were applied to mature cotton plants as tank-mixed emulsifiable concentrates with a water carrier. DT₅₀s (50% disappearance time) for azinphosmethyl and fenvalerate were 3.9 and 237 h, respectively. Simulated rain (51 mm in 1 h) was applied to the cotton plants at times ranging from 2 to 146 h after insecticide application to determine washoff characteristics for both compounds. Residues of both insecticides became increasingly resistant to wash-off with increasing time interval between insecticide application and initial rainfall, e.g., about 95% of the plant Xload washed off 2 h after application, whereas at 146 h <50% washed off. The mean amounts of both insecticides washed from the plants decreased with time and were related to the mean plant loads. The results of this study show that foliar pesticide application should be delayed when rain is imminent.     

Operational note effects of fipronil and lambda-cyhalothrin against larval Anopheles quadrimaculatus and nontarget aquatic mosquito predators in Arkansas small rice plots

The effects of fipronil and lambda-cyhalothrin, applied at rates labeled for control of the rice water weevil, Lissorhoptrus oryzophilus, on 3 nontarget indigenous insect species in Arkansas rice are described. Three replicates of untreated control checks and fipronil- and lambda-cyhalothrin-treated plots containing 3 sentinel cages each were performed. Ten 4th-stage larvae of Anopheles quadrimaculatus, 10 adult Tropisternus lateralis, or 10 adult Notonecta indica were placed within individual cages in small rice plots treated with ICON 6.2 FS (fipronil) at 0.025 lb active ingredient (AI)/acre (0.028 kg/ha) or KARATEZ 2.08 CS (lambda-cyhalothrin) at 0.03 lb AI/acre (0.033 kg/ha) applied over vegetation and water with a single-boom sprayer. At 24 h after treatment in fipronil plots, significantly higher control of An. quadrimaculatus and T. lateralis (69 and 48% control, respectively) was achieved, compared to N. indica (18%). In lambda-cyhalothrin plots 24 h after treatment, 100% reductions of both T. lateralis and N. indica were highly significant (P < 0.05) from the lower level of control in An. quadrimaculatus (10%). At 48 h after treatment, no significant, differences existed between all species within fipronil plots, with An. quadrimaculatus, T. lateralis, and N. indica obtaining 41, 10, and 7% control, respectively. Significantly higher (P < 0.05) control was obtained in lambda-cyhalothrin plots 48 h after treatment, with 93 and 53% control of T. lateralis and N. indica, respectively, compared to 7% control of An. quadrimaculatus. A marked difference in susceptibility was found between selected nontarget organisms used in this study. When using lambda-cyhalothrin to control adult L. oryzophilus, populations of nontarget beneficial insects, such as T. lateralis and N. indica, could be adversely affected, whereas nontarget pestilent species, such as An. quadrimaculatus, could proliferate. Fipronil achieved higher percentages of control against An. quadrimaculatus, compared to lambda-cyhalothrin, and was less harmful to both nontarget predators.     

Rice Consumption and Urinary Arsenic Concentrations in U.S. Children

Background: In adult populations, emerging evidence indicates that humans are exposed to arsenic by ingestion of contaminated foods such as rice, grains, and juice; yet little is known about arsenic exposure among children.Objectives: Our goal was to determine whether rice consumption contributes to arsenic exposure in U.S. children.Methods: We used data from the nationally representative National Health and Nutrition Examination Survey (NHANES) to examine the relationship between rice consumption (measured in 0.25 cups of cooked rice per day) over a 24-hr period and subsequent urinary arsenic concentration among the 2,323 children (6–17 years of age) who participated in NHANES from 2003 to 2008. We examined total urinary arsenic (excluding arsenobetaine and arsenocholine) and dimethylarsinic acid (DMA) concentrations overall and by age group: 6–11 years and 12–17 years.Results: The median [interquartile range (IQR)] total urinary arsenic concentration among children who reported consuming rice was 8.9 μg/L (IQR: 5.3–15.6) compared with 5.5 μg/L (IQR: 3.1–8.4) among those who did not consume rice. After adjusting for potentially confounding factors, and restricting the study to participants who did not consume seafood in the preceding 24 hr, total urinary arsenic concentration increased 14.2% (95% confidence interval: 11.3, 17.1%) with each 0.25 cup increase in cooked rice consumption.Conclusions: Our study suggests that rice consumption is a potential source of arsenic exposure in U.S. children.     

Field and laboratory studies to assess the effects of Vertimec(®) 18EC on Daphnia similis

The present study aimed to evaluate the interactions of the pesticide Vertimec(?) 18EC in aquatic ecosystems. In this respect, soil plots were contaminated with Vertimec(?) 18EC at the concentration indicated for strawberry crops (0.125L of solution m(-2)). After the contamination, torrential rainfall was simulated and the surface runoff was collected and transferred to mesocosm tanks in five treatments, run in triplicate: (1) control-C; (2) runoff from an uncontaminated plot-UR; (3) runoff from the plot contaminated with Vertimec(?) 18EC-CR; (4) direct application of Vertimec(?) 18EC in the water-V and (5) water samples gathered randomly to verify whether there was contamination between the mesocosms-RS. Water samples from these tanks were also submitted to ecotoxicological tests with Daphnia similis and analyses to evaluate the limnological characteristics, in five collection periods over 10 days (240h). Physical and chemical differences were observed in the water samples, mainly related to increased turbidity, suspended solids and nutrients (nitrogen and phosphate forms). Acute toxicity was observed for the direct application treatment for the entire experimental period, and in some periods for the CR treatment (from 48h to 168h). The results obtained suggest that the pesticide did not fully degrade during the study period (10 days) in the direct application treatment, demonstrating that the presence of other substances in the commercial formulation contribute to the maintenance of toxicity. This represents a potential risk for aquatic ecosystems in areas adjacent to where the chemical is applied.     

Evaluation of methylated soy oil and water-based formulations of Bacillus thuringiensis var. Israelensis and Golden Bear Oil (GB-1111) against anopheles quadrimaculatus larvae in small rice plots

The efficacy of formulations containing methylated soybean oil (MSO) alone and with technical-grade Bacillus thuringiensis var. israelensis (Bti) were compared to Golden Bear Oil (GB-1111) and a water-based Bti formulation against 3rd- to 4th-stage Anopheles quadrimaculatus larvae confined to sentinel cages in small rice plots. Three replicates each of MSO with 2% Pyroter added as a surfactant (MSO + PYR), MSO with 2% Pyroter and 4 g of Bti technical powder (MSO + PYR + Bti), GB-1111, a water-based formulation with 4 g of Bti technical powder (Bti + water), and untreated controls were performed. Mosquito larvae were introduced on the 1st day of treatment and at 4 days posttreatment. Mortality was recorded at 24 and 48 h posttreatment for the 1st installation and at 5 days posttreatment for the 2nd installation. The Bti + water formulation provided 71% control and the MSO + PYR + Bti formulation achieved 64% control, whereas MSO + PYR and GB-1111 produced 16 and 18% control, respectively, at 24 h posttreatment. With the exception of MSO + PYR + Bti, which decreased by 2%, the mean percent control increased slightly at 48h posttreatment across remaining treatments, with Bti + water obtaining 72% control. This was significantly higher than GB-1111, which achieved 23% control at 48 h posttreatment. The MSO + PYR and MSO + PYR + Bti formulations yielded 56 and 62% control, respectively, during the same interval and were not significantly different from one another. Formulations containing MSO + PYR exhibited delayed activity similar to GB-1111, with all formulations except MSO + PYR + Bti providing greatest control at 48 h posttreatment. Both MSO formulations (MSO + PYR + Bti and MSO + PYR) were statistically comparable to Bti + water and GB-1111, respectively, at 24 and 48 h posttreatment. None of the formulations exhibited a residual activity adequate enough to control An. quadrimaculatus larvae for up to 5 days.     

Uptake of 137Cs and 90Sr in rice plants

In order to study the transfer of water-borne 137Cs and 90Sr into rice plants, pot experiments were done by growing rice plants on soils taken from rice beds near two nuclear power plants: Qinshan Nuclear Power Plant and Daya Bay Nuclear Power Plant in China. The vertical migration of 137Cs and 90Sr in the soil samples was studied, and results show that almost all the contaminants were retained in the top 1 cm of soil with at most a few percent down to 3 cm of soil. The areal transfer factors of 137Cs and 90Sr were studied by adding various activity concentrations of the two radionuclides to the irrigation water and then measuring the activity concentration in the various rice tissues. The areal transfer factors were also analyzed for their dependence on soil characteristics, time and duration of the contamination. The areal transfer factors obtained in this study refer to the absorption of the fallout nuclides deposited in the irrigation water in a rice field as opposed to other studies that deal with uniform activity concentration in the soils.     

Fate and toxicity of temephos applied to an intertidal mangrove community

The distribution, persistence, and toxicity of the mosquito larvicide temephos was monitored following aerial applications to an intertidal mangrove community in Lee County, Florida. The amount of temephos penetrating to the mangrove floor ranged from 15 to 70% of the amount entering the upper leaf canopy, with 50-60% of that applied remaining on the mangrove leaves. Rainfall caused an additional influx of temephos from the leaves to the mangrove floor. Residues were detected in intertidal water at 2 h, but not 4 h after application. However, temephos was observed to persist in simulated tidal pools and on mangrove leaves for up to 72 h and in oysters for up to 48 h after application. Marine organisms placed in cages at 3 test sites and a control site were monitored for toxic effects. Mortality among natural mosquito larvae was simultaneously monitored. Mysids (Mysidopsis bahia) exhibited a significant mortality at one site during 1 of 3 applications monitored; however, no correlation was observed between mortality and temephos concentration in water. No significant mortality was observed for the other organisms, which included: brown shrimp (Panaeus aztecus), grass shrimp (Palaemonetes pugio), juvenile snook (Centropomis undecimalis) and sheepshead minnow (Cyprinodon variegatus).     

Zinc biofortification of rice in China: a simulation of zinc intake with different dietary patterns

A cross-sectional survey of 2819 adults aged 20 years and above was undertaken in 2002 in Jiangsu Province. Zinc intake was assessed using a consecutive 3-day 24-h dietary recall method. Insufficient and excess intake was determined according to the Chinese Dietary Recommended Intakes. Four distinct dietary patterns were identified namely "traditional", "macho", "sweet tooth", and "healthy". Intake of zinc from biofortified rice was simulated at an intermediate zinc concentration (2.7 mg/100 g) and a high zinc concentration (3.8 mg/100 g) in rice. Average total zinc intake was 12.0 ± 3.7 mg/day, and insufficiency of zinc intake was present in 15.4%. Simulated zinc intake from biofortified rice with intermediate and high zinc concentration decreased the prevalence of low zinc intake to 6.5% and 4.4%, respectively. The effect was most pronounced in the "traditional" pattern, with only 0.7% of insufficiency of zinc intake remaining in the highest quartile of the pattern. Zinc intake was inversely associated with the "sweet tooth" pattern. Zinc biofortifed rice improves dietary zinc intake and lowers risk for insufficient zinc intake, especially for subjects with a more "traditional" food pattern, but less for subjects with a "sweet tooth" food pattern.     

Effects of incorporating germinated brown rice on the antioxidant properties of wheat flour chapatti

Brown rice after germinating for 24 and 48?h was milled into flour and incorporated in whole wheat flour at a level of 10% to prepare chapattis. The objective was to use chapatti as a delivery vehicle for germinated brown rice. The flour blends and chapattis made from the flour blends were evaluated for their antioxidant properties. Incorporating germinated brown rice flour increased the total phenolic content of the flour blend from 1897 to 2144?μg FAE/g. The total flavonoids content increased significantly from 632.3 to1770.9?μg CAE/g and metal chelating activity significantly increased by 71.62%. Antioxidant activity increased significantly by the addition of brown rice flour and addition of 24- and 48-h germinated brown rice flour further increased the antioxidant activity significantly. The total phenolic content and total flavonoids content decrease significantly in all the blends after baking the flour into chapatti. A decrease of 3% to 29% was observed in the total phenolic content and a decrease of 25% to 42% was observed in the total flavonoids content. However, baking of the flour blends into chapatti increased the reducing power, metal chelating activity by three folds and antioxidant activity from 64% to 104%.     

Toxicity of Parking Lot Runoff After Application of Simulated Rainfall

Stormwater runoff is an important source of toxic substances to the marine environment, but the effects of antecedent dry period, rainfall intensity, and duration on the toxicity of runoff are not well understood. In this study, simulated rainfall was applied to parking lots to examine the toxicity of runoff while controlling for antecedent period, intensity, and duration of rainfall. Parking areas were divided into high and low use and maintained and unmaintained treatments. The parking stalls were cleaned by pressure washing at time zero. Simulated rainfall was then applied to subplots of the parking lots so that antecedent periods of 1, 2, and 3 months were achieved, and all of the runoff was collected for analysis. On a separate parking lot, rainfall was applied at a variety of intensities and durations after a 3-month antecedent period. Runoff samples were tested for toxicity using the purple sea urchin fertilization test. Every runoff sample tested was found to be toxic. Mean toxicity for the sea urchin fertilization test ranged from 2.0 to 12.1 acute toxic units. The toxicity increased rapidly during the first month but then decreased approximately to precleaning levels and remained there. No difference in toxicity was found between the different levels of use or maintenance treatments. The intensity and duration of rainfall were inversely related to degree of toxicity. For all intensities tested, toxicity was always greatest in the first sampling time interval. Dissolved zinc was most likely the primary cause of toxicity based on toxicant characterization of selected runoff samples.     

某钒厂石煤原矿样品中210Po的分析

目的 建立石煤中²¹⁰Po的分析方法,分析石煤中²¹⁰Po的含量。方法 针对某火法-湿法联合工艺钒厂原料车间的石煤原矿样品,采用湿式灰化、²⁰⁹Po标准溶液示踪、银片自制渡源的方法分析石煤样品中²¹⁰Po含量。结果 石煤原矿样品中²¹⁰Po的平均含量为（359.5 ±7.6） Bq·kg^-1,相对误差为2.1%,回收率为（60.0% ±3.2%）;测量48 h,样品中²¹⁰Po的最小可探测限为1.8 Bq·kg^-1。结论 石煤中²¹⁰Po含量较高,需关注火法-湿法联合工艺提钒生产中²¹⁰Po的转移、富集和排放,以及相应的辐射环境影响问题。     

Field scale quantification of microbial transport from bovine faeces under simulated rainfall events

The dispersion and transport of Cryptosporidium parvum oocysts, Escherichia coli and PRD1 bacteriophage seeded into artificial bovine faecal pats was studied during simulated rainfall events. Experimental soil plots were divided in two, one sub-plot with bare soil and the other with natural vegetation. Simulated rainfall events of 55 mm.h(-1) for 30 min were then applied to the soil plots. Each experimental treatment was performed in duplicate and consisted of three sequential artificial rainfall events ('Runs'): a control run (no faecal pats); a fresh faecal pat run (fresh faecal pats); and an aged faecal pat run (one week aged faecal pats). Transportation efficiency increased with decreasing size of the microorganism studied; Cryptosporidium oocysts were the least mobile followed by E. coli and then PRD1 phage. Rainfall events mobilised 0.5 to 0.9% of the Cryptosporidium oocysts, 1.3-1.4% of E. coli bacteria, and 0.03-0.6% of PRD1 bacteriophages from the fresh faecal pats and transported them a distance of 10 m across the bare soil sub-plots. Subsequent rainfall events applied to aged faecal pats only mobilised 0.01-0.06% of the original Cryptosporidium oocyst load, between 0.04 and 15% of the E. coli load and 0.0006-0.06% of PRD1 bacteriophages, respectively.     

Oral mifepristone 600 mg and vaginal gemeprost for mid-trimester induction of abortion: An open multicenter study

This open multicenter study was performed in 20 hospital gynecological units in the UK. The effects of 600 mg oral mifepristone as pretreatment to vaginal prostaglandin induction of second second trimester abortion was studied in 267 women.

The primary efficacy variable was the abortion induction interval, defined as the time taken to expel the fetus from the time of administration of the first prostaglandin pessary. Induction was commenced 36 to 48 hours following mifepristone intake.

The mean abortion induction interval was 7 h. A total of 81.9% of women aborted within 12 h. There was a significant relationship between abortion induction interval and age of gestation, and a significant inverse relationship between abortion induction interval and parity.

Vomiting, pelvic pain, and nausea were the most frequently reported adverse events. Two patients required transfusion and one patient with a uterine scar from a previous cesarean section suffered a ruptured uterus and hysterotomy.     

Mifepristone-misoprostol midtrimester abortion: impact of gestational age on the induction-to-abortion interval

Background

This study was conducted to explore the effect of gestational age (GA) on the induction-to-abortion interval of mifepristone-misoprostol midtrimester termination of pregnancy (TOP) regimen.

Study Design

This study involved a consecutive series of 270 pregnancies between 12.0 and 22.6 weeks that have undergone legal TOP from April 2006 to June 2009. All women received a single oral dose of 200 mg mifepristone and, 36-48 h later, a course of misoprostol (an initial vaginal dose of 800 mcg plus four oral doses of 400 mcg at 3-hourly intervals). Treatment was considered to be a failure if abortion did not occur within 24 h. The impact of GA, parity and maternal age on the induction-to-abortion interval was assessed by means of Cox regression.

Results

Overall, the mean GA at TOP was 18.0 weeks. The mean induction-to-abortion interval was 9.8 h (SD=8.2 h; range=1-50 h), and 246 women (91%) aborted successfully within 24 h. GA at TOP and parity were the only two variables independently associated with the induction-to-abortion interval. The mean induction-to-abortion interval was increased by about 50% in patients undergoing TOP between 20.0 and 22.6 weeks (12.9 h, SD=8.9), as compared with those at 16.0-19.6 weeks (7.8 h, SD=5.9) and 12.0-15.6 weeks (8.2 h, SD=8.3) (p<.001). The effect of parity on the induction-to-abortion interval was more modest, with a 20% increase in induction-to-abortion interval in nulliparous (10.1 h, SD=9.1), as compared with women with a previous live birth (8.1 h, SD=6.7).

Conclusions

The mean induction-to-abortion interval increases by 4 h after 20 weeks GA. This information may be relevant for counseling and planning of the procedure.     

Ion-release kinetics and ecotoxicity effects of silver nanoparticles

The environmental toxicity associated with silver nanoparticles (AgNPs) has been a major focus in nanotoxicology. The Ag(+) released from AgNPs may affect ecotoxicity, although whether the major toxic effect is governed by Ag(+) ions or by AgNPs themselves is unclear. In the present study, we have examined the ecotoxicity of AgNPs in aquatic organisms, silver ion-release kinetics of AgNPs, and their relationship. The 48-h median effective concentration (EC50) values for Daphnia magna of powder-type AgNP suspensions were 0.75?μg/L (95% confidence interval [CI]?=?0.71-0.78) total Ag and 0.37?μg/L (95% CI?=?0.36-0.38) dissolved Ag. For sol-type AgNP suspension, the 48-h EC50 values for D. magna were 7.98?μg/L (95% CI?=?7.04-9.03) total Ag and 0.88?μg/L (95% CI?=?0.80-0.97) dissolved Ag. The EC50 values for the dissolved Ag of powder-type and sol-type AgNPs for D. magna showed similar results (0.37?μg/L and 0.88?μg/L) despite their differences of EC50 values in total Ag. We observed that the first-order rate constant (k) of Ag(+) ions released from AgNPs was 0.0734/h at 0.05?mg/L total Ag at 22°C within 6?h. The kinetic experiments and the toxicity test showed that 36% and 11% of sol-type AgNPs were converted to the Ag(+) ion form under oxidation conditions, respectively. Powder-type AgNPs showed 49% conversion rate of Ag(+) ion from AgNPs. We also confirmed that Ag(+) ion concentration in AgNP suspension reaches an equilibrium concentration after 48?h, which is an exposure time of the acute aquatic toxicity test.     

Problems in the interpretation of small area analysis of epidemiological data: the case of cancer incidence in the West of Scotland.

STUDY OBJECTIVE--The aim was to examine the extent to which random variation alone will produce differences in observed incidence rates between small areas which will affect measures of spatial clustering and estimates of relative risk. DESIGN--This was a study of changes in the pattern of spatial concentration of cancer incidence over a five year time period. A comparison was made of observed incidence rates for 34 tumour sites with randomly generated values and, where possible, with expected values derived from known relative risks. SETTING--Twenty six local government districts in the West of Scotland. MAIN RESULTS--A statistically significant relationship was observed between sample size and the stability of a summary measure of spatial concentration. Almost all observed highest:mean rate ratios were within the 95% confidence interval of the simulated distribution of these values. In three cases examined, both observed and simulated highest:lowest rate ratios were larger than those expected on the basis of known exposures to risk. CONCLUSIONS--In the absence of a prior hypothesis, small area analysis of epidemiological data for periods of less than 10 years will almost always give misleading results for all but the most common diseases.     

Deposition velocity of gaseous I to rice grains

Among the routes of gaseous I transfer to rice grains, direct deposition to the hull of rice plants and the subsequent transfer to brown rice and polished rice should be more critical than leaf absorption-translocation. A grain number normalized deposition velocity (Vs) is recommended as a key parameter to assess the amount of gaseous I deposited on the rough rice. This parameter is given as "iodine content per unit number of grain per unit time" divided by "iodine concentration per unit volume of the air." After the heading period the surface area of rough rice is almost constant but weight increases with time. Therefore, mass normalized deposition velocity (VD) varies with time. By introducing Vs instead of VD, the variations could be converged into narrow ranges. The contribution of gaseous I from the atmosphere to rough rice, brown rice and polished rice were estimated using Vs values obtained experimentally and gaseous I concentration in the air.     

不同浓度敌鼠钠盐毒鼠效果比较

作者应用0.5/万、1/万、2/万、5/万浓度敌鼠钠盐毒饵,在实验室和现场进行了灭鼠效果比较。在实验室给小鼠饲毒饵三天,4个浓度组鼠的死亡率差别无显著性(x~2=2.1339 P>0.05);在住宅区连续投放三天毒饵,0.5/万与1/万组灭鼠效果相同,以2/万组灭鼠效果最好;在农田区一次性投放毒饵,0.5/万组灭效低于其他组,1/万、2/万、5/万组灭鼠率差别无显著性(x~2=4.0229 P>0.05)。还发现,敌鼠钠盐毒饵浓度越低,越易被鼠接受,但出现死鼠的时间也随之推迟。根据本文结果和资料报告综合分析,作者认为:敌鼠钠盐毒饵在住宅区和农田区毒鼠时,以2/万浓度分别采用饱和投毒法和间隔投毒法较好。