Nitrates in industrial and traditional tomato paste from Arsenjan City, Iran: a health risk assessment study.

A comprehensive approach was used for the first time to measure NO3- risk in tomato paste consumption; besides a robust deterministic and probabilistic method was used. The mean levels of NO3- in homemade and industrial tomato paste were 7.36 mg/kg and 43.69 mg/kg, respectively. The Monte Carlo simulation confirmed that these values were below normal levels (HQ less than 1). The sensitivity analysis displayed that FIR was the main factor affecting the risk to human health in both groups. The interactive plot demonstrated the interaction between C and IR for children and adults in both types of tomato paste. This study concludes that NO3- ingestion due to tomato paste consumption poses no significant health risk. However, considering that food and water constitute the primary sources of NO3- intake, continuous monitoring is recommended due to potential health risks associated with excessive NO3- consumption, including certain forms of cancer.

Designing the pH-sensitive indicator based on starch nanoparticle with bromocresol green for monitoring meat spoilage.

The starch nanoparticle, combined with bromocresol green (BCG), served as a pH-sensitive indicator to monitor meat quality throughout an 8-day refrigerated storage period. The meat samples were sealed in package which the pH-sensitive indicator attached to the interior part of packaging lid. The changes in meat quality were evaluated by total volatile base nitrogen (TVBN), pH, total viable count (TVC), sensory analysis, and color in interval of 0, 3, 5, 7, and 8-days storage at 4°C. Initial TVBN values were recorded at 19.6 mg/100 g, increased to 26.6 mg/100 g by the end of storage period. The pH value was significantly increased after 8 days storage at 4°C. The observed color variation in the indicator from yellow to blue was attributed to the concurrent increases in TVBN, TVC, and pH. The indicator color changes had significant correlation with analyzed chemical quality of stored meat. Therefore, the designed BCG pH-sensitive indicator could be effective in monitoring the meat spoilage during storage.

Expression analysis of circulating miR-22, miR-122, miR-217 and miR-367 as promising biomarkers of acute lymphoblastic leukemia.

BACKGROUND: The role of serum-based biomarkers such as microRNAs in cancer diagnosis has been extensively established. This study aimed to determine the expression levels of bioinformatically selected miRNAs and whether they can be used as biomarkers or a new therapeutic target in patients with acute lymphoblastic leukemia (ALL). MATERIALS AND METHODS: The expression levels of serum miR-22, miR-122, miR-217, and miR-367 in 21 ALL patients and 21 healthy controls were measured using quantitative real-time PCR. The receiver operating characteristic (ROC) curve and the associated area under the curve (AUC) was used to assess candidate miRNAs' diagnostic value as a biomarker. RESULTS: The results showed that miR-217 was markedly decreased in patients with ALL compared to controls. Moreover, miR-22, miR-122, and miR-367 were found to be upregulated. Furthermore, ROC analysis showed that serum miR-217 and miR-367 could differentiate ALL patients from healthy individuals, while miR-22 has approximate discriminatory power that requires further investigation. CONCLUSION: These results provide promising preliminary evidence that circulating miR-217 and miR-367 could be considered potent diagnostic biomarkers and therapeutic goals in this disease.

Pyridoxamine protects human granulosa cells against advanced glycation end-products-induced steroidogenesis disturbances.

BACKGROUND: Ovarian advanced glycation end-products (AGEs) accumulation is associated with ovarian granulosa cells (GCs) dysfunction. Vitamin B6 derivatives positively affected reproduction. The current study was conducted to elucidate the AGEs effects on human luteinized mural GCs steroidogenesis in the presence or absence of pyridoxamine (PM). METHODS AND RESULTS: Isolated GCs of 50 healthy women were divided into four parts and treated with media alone (Control), PM alone, or human glycated albumin (HGA) with/without PM. Main steroidogenic enzymes and hormones were assessed by qRT-PCR and ELISA. The AGE receptor (RAGE) protein was also determined using Western blotting. The non-toxic concentration of HGA increased the expression of RAGE, StAR, 3ß-HSD, and 17ß-HSD (P < 0.0001 for all) but decreased the expression of CYP19A1 at mRNA levels. The increased RAGE protein expression was also confirmed by western blot analysis. These effects resulted in declined estradiol (E2), slightly, and a sharp rise in progesterone (P4) and testosterone (T) levels, respectively. PM, on its own, ameliorated the HGA-altered enzyme expression and, thereby, corrected the aberrant levels of E2, P4, and T. These effects are likely mediated by regulating the RAGE gene and protein expression. CONCLUSION: This study indicates that hormonal dysfunctions induced by the AGEs-RAGE axis in luteinized GCs are likely rectified by PM treatment. This effect is likely acquired by reduced expression of RAGE. A better understanding of how AGEs and PM interact in ovarian physiology and pathology may lead to more targeted therapy for treating ovarian dysfunction.

Field scale spatio-temporal variability of wind erosion transport capacity and soil loss at Urmia Lake.

Urmia Lake has been known as the second hypersaline lake in the world, with the surface area of approximately 5200 km2. With decreasing the water input of the lake due to anthropogenic activities, the susceptible areas to wind erosion and dust emission were extended during the last decades. The present study attempted to measure wind erosion on the edge of Urmia Lake for three years since 2017. In order to provide a quantitative understanding of wind erosion parameters in the dried up Urmia Lake area, and to prioritize different areas in terms of wind erosion intensity, it was necessary to establish wind erosion measurement and monitoring stations in different areas of dried up shores. Wind erosion measurement and monitoring stations were established in six erodible areas such as Salmas, Jabal Kandi, Soporghan, Miandoab, Khaselou and Ajabshir. Wind erosion parameters such as transport capacity and soil loss in the dried margin of Urmia Lake were determined. For this purpose, BSNE traps were used in the layout of two circles having an identical center. After each wind erosion event, sediment traps were emptied and weighted; then, the vertical and horizontal distribution of the particulate matters was calculated. Comparison of the values of maximum transport capacity-fmax (kg/m.yr) and soil loss- SL (ton/ha.yr) of aeolian particulate in 2017 showed that the two main centers of wind erosion on the edge of Urmia Lake were Ajabshir and Jabal Kandi. The stations of Khaselou, Salmas, Soporghan and Mianduab were in the declined ranking. Results showed that the transfer capacity values were 351.97 and 297.30 kg/m/year and soil losses were 18.04 and 35.4 ton/ha/year, respectively, for the stations with high wind erosion potential, i.e., Ajab Shir and Jabal Kandi, in 2017. Furthermore, these values were significantly reduced for the mentioned stations in 2019, so that the values obtained from the transfer capacity reached 54.93 and 40.39 kg/m/year and soil losses reached 3.70 and 2.43 ton/ha. Investigating the results of transport capacity and soil loss showed the decreasing trend in wind erosion rate due to the increasing water level of the lake as well as biological and engineering conservation practices (non-live windbreaks) from 2017 to 2019.

Health risk assessment and spatial distribution of nitrate, nitrite, fluoride, and coliform contaminants in drinking water resources of kazerun, Iran.

Exposure to nitrate, nitrite, and fluoride through drinking water consumption, especially in arid and semi-arid regions, has been considered by many researchers. Therefore, the present study aimed to investigate the status of nitrate, nitrite, fluoride, and total coliforms in water supply sources of Kazerun located in Fars province, Iran, determine their spatial distribution, and perform health risk assessment in four age groups (infants, children, teenagers, and adults). In this research, the concentration data of 25 groundwater wells were examined. Then, the spatial distribution of the contaminants was determined using the Arc GIS software (v. 10.5) and their health risk assessment was performed via the standard method of the US Environmental Protection Agency. The maximum concentrations of nitrate, nitrite, and fluoride were 25.5, 0.056, and 0.72 mg/l, respectively and their mean concentrations were 13.5, 0.008, and 0.52 mg/l, respectively. In addition, the mean and maximum concentrations of coliforms were 371.21 and 2694.50 CFU/100 ml, respectively. The total coliforms value was higher than the permissible limit in 60 % of the cases. The highest Chronic Daily Intake (CDI) of the studied contaminants was related to nitrate among children (range: 0.21-1.45, with an average value of 0.77 mg/kg-day). Moreover, the Hazard Quotient (HQ) values were below 1 for all contaminants and in all age groups. The highest HQ value (0.9) belonged to nitrate amongst children. Furthermore, the Hazard Index (HI), as a cumulative effect of HQ, was calculated for all three contaminants and the results showed that it was greater than 1 in 56 % of the cases among children, which was considered a serious risk. The findings revealed no significant relationship between nitrate and nitrite concentrations and total coliforms. Overall, nitrate seemed to play a more critical role in the health risk of the exposed age groups in comparison to nitrite and fluoride. Hence, appropriate managerial measures are recommended to be taken.

Health risk assessment of exposure to atrazine in the soil of Shiraz farmlands, Iran.

Atrazine-contaminated soils can pose a carcinogenic and non-carcinogenic health risk through different routes for exposed people. This study aimed to assess the health risk of exposure to atrazine-contaminated soils through direct ingestion and dermal contact in farmlands nearby Shiraz. Atrazine concentration was measured in 22 selected sites using grid sampling. The carcinogenic and non-cancer risks associated with dermal and ingestion exposure in children and adults were estimated. The lowest and highest atrazine concentrations were in S1 (0.015 mg/kg soil) and S22 (0.55 mg/kg soil). Hazard Index (HI)1 values ranged from 0.007 to 0.25 for children, and the values ranged from 0.0008 to 0.03 for adults. The mean cancer risk for children and adults was 6.01 × 10-4 and 7.40 × 10-5, respectively. The HI value was less than 1 for all sampling sites, indicating that exposure to atrazine does not threaten children and adults. However, the cancer risk exceeds the United States Environmental Protection Agency (US.EPA)2 threshold risk limit (10-6 to 10-4) in all sampling sites. Therefore, it is recommended that children should avoid playing on atrazine-contaminated farms or soils near anywhere atrazine may have been used.

Health risks of inhalation exposure to BTEX in a municipal wastewater treatment plant in Middle East city: Shiraz, Iran.

Benzene, toluene, ethylbenzene, and xylene, known as BTEX, adversely affect human health. This study aimed to measure BTEX concentration and assess the health risk through inhalation exposure to these compounds in a municipal wastewater treatment plant. The ambient air samples were collected using the active sampling method in summer and winter. Sampling sites were close to wastewater treatment units, including bar screen & grit chamber (Site-1), aeration tank & secondary clarifiers (Site-2), anaerobic sludge digester (Site-3), and office & control building (Site-4). Results indicate that the mean levels of benzene and toluene in winter were higher than in summer. The levels of benzene and toluene were below the occupational exposure levels of the American Conference of Governmental Industrial Hygienists (ACGIH) and Occupational Safety and Health Administration (OSHA). The carcinogenic risk (CR) and hazard quotient (HQ) were assessed using the United States Environmental Protection Agency (U.S.EPA) method, and Monte Carlo simulation (MCS) was applied to quantify the uncertainty and sensitivity analysis. The CRs for all sampling sites were below the U.S.EPA threshold limit (1.0 × 10-4). The HQ values for benzene nearby Site-2 were above 1.0, indicating inhalation exposure could pose a health hazard. Besides, the HQ results for exposure to toluene in all sampling sites were less than 1.0. The sensitivity analysis had shown that the risk determinant for carcinogenic and non-carcinogenic risk was exposure time, followed by concentration.

Potential of nanochitosan coating combined with walnut green husk to improve the preservation of rainbow trout (Oncorhynchus mykiss) during refrigerated storage.

The present study evaluated the potential of nanochitosan coating enriched with ethanol-water extract of the walnut green husk (WGHE) on spoilage and rancidity of rainbow trout (Oncorhynchus mykiss) during six-day refrigerated storage. Hence, we have considered fresh trout fillets without any treatment as control (C), immersed in 2% solution of chitosan nanoparticles (CN), combination with 1.5% and 3% WGHE with nanochitosan coating (CN + WGHE 1.5 and CN + WGHE3), for physicochemical, microbial and sensorial assays. The highest levels and total volatile nitrogen were observed after day 6 in C, while the lowest was found in CN + WGHE3 groups. Thiobarbituric acid reactive substance (TBARS) and peroxide value of untreated fillets on day 6 of the study were significantly higher than NC + WGHE3 with 0.08 mg/g and 3.27 mEq/kg, respectively. The total microbial population was: C ˃ CN ˃ CN + WGHE 1.5 > CN + WGHE3, which expresses the effect of the extract on the total microbial population. Overall, the combination of WGHE with CN increased the extract's efficiency in reducing peroxide value, TBARS, and total volatile nitrogen and delayed the pH increase, improving the overall acceptability of rainbow trout fillets stored in refrigerated conditions.

Comparative photo-oxidative degradation of etodolac, febuxostat and imatinib mesylate by UV-C/H2O2 and UV-C/S2O82- processes: Modeling, treatment optimization and biodegradability enhancement.

The pharmaceutical contamination in aquatic environment has arisen increasing concern due to its potentially chronic toxicity. In recent years, HO° and SO4°- based advanced oxidation processes (AOPs) have been widely applied in water and wastewater treatments due to their highly efficiency on contaminant removal. Here, the response surface modeling (RSM) was used to investigate the degradation of three typical pharmaceuticals (i.e., etodolac (ETD), febuxostat (FBU) and imatinib mesylate (IMT)) by UV/H2O2 and UV/S2O82- processes. Based on the multiple regression analysis on full factorial design matrix and calculated reaction rate constants, the RSM was built. The experimental rate constants under optimal conditions were quite close to those obtained from the model, implying the good fit of the RSM. In addition, the RSM results indicated that UV/S2O82- process was less sensitive to pH in comparison to the UV/H2O2 process on target contaminant removal. Finally, it showed that UV/S2O82- process was superior to the UV/H2O2 process to on the enhancement of target contaminant biodegradability.

The residual nitrate and nitrite levels in meat products in Iran: A systematic review, meta-analysis and health risk assessment.

This study was designed to investigate the mean residual nitrite and nitrate levels in meat products, in Iran and to evaluate their health-related risks. After reviewing 799 studies, 15 were finally selected, their information was recorded and examined using Stata software. The results of the present study show that the mean residual nitrite and nitrate levels in meat products was about 55.18 and 95.09 ppm, respectively. The residual nitrite level is different in various meat products, so that the residual nitrite level in sausages and kielbasa is 54.52 and 56.87 ppm, respectively. Also, the present study shows that the mean residual nitrate level in sausages and kielbasa was 77.21 and 121.49 ppm, respectively. Health Risk Index (HRI) of nitrite and nitrate were 0.1541 and 0.0050, respectively, which were lower than 1 value. Therefore, there is no considerable carcinogenic risk for consumers in Iran. Taking together, these residues must be continuously monitored by relevant authorities.

A process mining approach in big data analysis and modeling decision making risks for measuring environmental health in institutions.

This paper aimed to introduce a process-mining framework for measuring the status of environmental health in institutions. The methodology developed a new software-based index namely Institutional Environmental Health Index (IEHI) that was integrated from ontology-based Multi-Criteria Group Decision-Making models based on the principles of fuzzy modeling and consensus evaluation. Fuzzy Ordered Weighting Average (OWA) with the capability of modeling the uncertainties and decision-making risks along with Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) were employed as the computation engine. The performance of the extended index was examined through an applied example on 20 mosques as public institutions. IEHI could analyze big data collected by environmental health investigators and convert them to a single and interpretable number. The index detected the mosques with very unsuitable health conditions that should be in priority of sanitation and suitable ones as well. Due to the capability of defining the type and numbers of criteria and benefitting from specific and user-friendly software namely Group Fuzzy Decision-Making, this index is highly flexible and practical. The methodology could be used for numerating the environmental health conditions in any intended institution or occupation. The proposed index would provide e-health assessment by more efficient analysis of big data and risks that make more realistic decisions in environmental health system.

Antibiotic residues in poultry tissues in Iran: A systematic review and meta-analysis.

To control the drug residues in foods, the national Maximum Residue Limits (MRLs) have been determined by the international organizations; however, no regulation has been complied for MRL in food animals in Iran. This study was a systematic review and meta-analysis about studies of antibiotic residues in slaughtered poultry carcasses, in Iran. The information was first collected and analyzed throughout six international databases, and four Iranian national databases. According to the data, the total prevalence of antibiotic residues was obtained as 39.41%, 5.40%, and 0.30% using four-plate test (FPT), High-Performance Liquid Chromatography (HPLC), and Enzyme-linked immuno_sorbent assay (ELISA) methods, respectively. The highest prevalence of the residues was shown in the liver by both methods of HPLC (47.75%) and ELISA (14.35%). Moreover, the total mean of antibiotics was recorded as 71.03 ppb and 65.86 ppb in different tissues using the HPLC and ELISA method, respectively. Based on this study, we can conclude that the prevalence of antibiotic residue in poultry meat in Iran is high and that this level does not cause health problems for consumers. It is highly recommended to execute tight surveillance strategies from the government in antibiotic monitoring.

Determination of chloroform concentration and human exposure assessment in the swimming pool.

This cross-sectional study aimed to examine the concentration of the by-products of chlorination in the swimming pool and estimate human health risk for the swimmers of Shiraz University of Medical Sciences. In this study, the chloroform concentrations of 16 samples were measured using Gas Chromatography (GC). All the measured concentrations were less than the allowed amount announced by the World Health Organization (WHO). The results of the cancer risk (CR) and hazard index (HI) showed that the major exposure routes were found to be dermal during swimming and the 95 percentile of estimated CR and HI for the male group were 1.38 × 10-10 and 1.82 × 10-5 respectively, which is higher than the values of 5.48 × 10-10 and 2.25 × 10-5 respectively, for the women group. Sensitivity analyses indicated that the swimming exposure time (ET), and chloroform concentration were the most relevant variables in the health risk model. Therefore, knowledge about the sources of micro-pollutants in swimming pools might help promote the health methods of the pool environment.

Studies on influence of process parameters on simultaneous biodegradation of atrazine and nutrients in aquatic environments by a membrane photobioreactor.

A Lab scale algal-bacterial membrane photobioreactor (MPBR) was designed and operated under 12-h light and 12-h dark conditions with a light intensity of 8000lx, in order to investigate the effects of initial concentrations of atrazine, carbon concentration, and hydraulic retention time on the ability of this photobioreactor in simultaneous removal of atrazine and nutrients in the continuous mode. The removal efficiencies of atrazine (ATZ), chemical oxygen demand (COD), phosphorus (PO43--P) and nitrogen (NOx) in optimum condition was more than 95%, 99%, 98% and 97% when the maximum removal rates were 9.5 × 10-3, 99.231, 11.773 and 7.762mg/L-day, respectively. Results showed that the quality of the effluent was reduced by the increase of atrazine concentration. The outcomes on the hydraulic and toxic shocks indicated that the system has a relatively good resistance to the shocks and can return to the stable conditions. Microalgae showed a great deal of interest and capability in cultivating and attaching to the surface of the membrane and bioreactor, and the total biomass accumulated in the system was greater than 6g/L. The kinetic coefficients of atrazine removal were also studied using various kinetic models. The maximum atrazine removal rate was determined by the modified Stover-Kincannon model. The results approved the ability of the MPBR reactor in wastewater treatment and microalgae cultivation and growth. The decline of atrazine concentration in this system could be attributed to the algal-bacterial symbiosis and co-metabolism process. Accordingly, the MPBR reactor is a practical, simple, economical and therefore suitable process for simultaneous biodegradation of chlorinated organic compounds and nutrients removal from aquatic environments.

Evaluation of kenaf fibers as moving bed biofilm carriers in algal membrane photobioreactor.

In this lab-scale study, the feasibility of using kenaf fibers as moving bed biofilm carriers in hybrid microalgal membrane photobioreactors (HMPBR) in organic matter and atrazine elimination from real secondary effluent was evaluated. For evaluating the kinetics of biofilm substrate consumption, an experimental model was proposed. Inoculation of wastewater samples with free carriers resulted in the greater removal of target pollutants. Removal efficiency of atrazine and chemical oxygen demand (COD) increased to 27% and 16%, with respect to the control, respectively. The total biomass accumulation in HMPBR exceeded 5g/L, and the microalgae tended to aggregate and attached to biofilm carriers. The removal efficiency of HMPBR improved significantly via inoculation of kenaf fiber carriers with bioremediation microalgal strains (p < 0.01). A lower stabilization ratio (VSS/TSS) was also recorded. The biomass in HMPBR included more lipids and carbohydrates. The results revealed that kenaf fibers could improve and upgrade the biological activity of different wastewater treatment applications, considering the great potential of biofilm carriers and their effluent quality.

Simultaneous removal of atrazine and organic matter from wastewater using anaerobic moving bed biofilm reactor: A performance analysis.

In this study, an anaerobic moving bed biofilm reactor (AMBBR) was designed to biodegrade atrazine under mesophilic (32 °C) condition and then it was evaluated for approximately 1 year. After biofilm formation, acclimation, and enrichment of microbial population within the bioreactor, the effect of various operation conditions such as changes in the concentration of influent atrazine and sucrose, hydraulic retention time (HRT), and salinity on the removal of atrazine and chemical oxygen demand (COD) were studied. In optimum conditions, the maximum removal efficiency of atrazine and COD was 60.5% and 97.4%, respectively. Various models were developed to predict the performance of atrazine removal as a function of HRT during continuous digestion. Also, coefficients kinetics was studied and the maximum atrazine removal rate was determined by Stover - Kincannon model (rmax = 0.223 kgATZ/m3d). Increasing salinity up to 20 g/L NaCl in influent flow could inhibit atrazine biodegradation process strongly in the AMBBR reactor; whereas, the reactor could tolerate the concentrations less than 20 g/L easily. Results showed that AMBBR is feasible, easy, affordable, so suitable process for efficiently biodegrading toxic chlorinated organic compounds such as atrazine. There was no accumulation of atrazine in the biofilm and the loss of atrazine in the control reactor was negligible; this shows that atrazine removal mechanism in this system was due to co-metabolism.

Biodegradation of atrazine from wastewater using moving bed biofilm reactor under nitrate-reducing conditions: A kinetic study.

In this study employed an anoxic moving bed biofilm reactor (AnMBBR) to evaluate the effects of hydraulic and toxic shocks on performance reactor. The results indicated a relatively good resistance of system against exercised shocks and its ability to return to steady-state conditions. In optimal conditions when there was the maximum rate of atrazine and soluble chemical oxygen demand (COD) removal were 74.82% and 99.29% respectively. Also, atrazine biodegradation rapidly declines in AnMBBR from 74% ±â€¯0.05 in the presence of nitrate to 9.12% only 3 days after the nitrate was eliding from the influent. Coefficients kinetics was studied and the maximum atrazine removal rate was determined by modified Stover & Kincannon model (Umax = 9.87 gATZ/m3d). Results showed that AnMBBR is feasible, easy, affordable, so suitable process for efficiently biodegrading toxic chlorinated organic compounds such as atrazine. Also, its removal mechanism in this system is co-metabolism.

A new recycling technique for the waste tires reuse.

In this series of laboratory experiments, the feasibility of using fixed bed biofilm carriers (FBBC) manufactured from existing reclaimed waste tires (RWTs) for wastewater treatment was evaluated. To assess polyamide yarn waste tires as a media, the fixed bed sequence batch reactor (FBSBR) was evaluated under different organic loading rate (OLRs). An experimental model was used to study the kinetics of substrate consumption in biofilm. Removal efficiency of soluble chemical oxygen demand (SCOD) ranged by 76-98% for the FBSBR compared to 71-96% in a sequencing batch reactor (SBR). Removal efficiency of FBBC was significantly increased by inoculating these RWTs carriers. The results revealed that the sludge production yield (Yobs) was significantly less in the FBSBR compared to the SBR (p < 0.01). It also produced less sludge and recorded a lower stabilization ratio (VSS/TSS). The findings show that the Stover-Kincannon model was the best fit (R2 > 99%) in a FBSBR. Results from this study suggest that RWTs to support biological activity for a variety of wastewater treatment applications as a biofilm carrier have high potential that better performance as COD and TSS removal and sludge settling properties and effluent quality supported these findings.

Cryopreservation of Bufotes viridis embryos by vitrification.

Loss of biodiversity among amphibians is a current concern. Our hypothesis is that the embryos of amphibian species at risk of extinction could be cryopreserved by vitrification, using methods which have proved successful with fish oocyte. To test this hypothesis, samples of four cryoprotectants - methanol (MeOH), dimethyl sulphoxide (Me2SO), propylene glycol (PG) and polyethylene glycol (PEG), some singly, some in combination, were plunged in liquid nitrogen for 5 min to find the best solution for vitrification. To find the least toxic of these solutions, blastulae and stage G17 embryos of Bufotes Viridis, a typical amphibian, were exposed to solutions at different concentrations (0.5-10 M) for different lengths of time (15-30 min), with and without their normal protective jelly coats. In each case the number of survivors, which reached stage G25 was counted. Finally a series of embryos was vitrified in liquid nitrogen using the most efficient and least toxic cryoprotectants. Propylene glycol had the best vitrification characteristics, but MeOH vitrified at higher concentrations. The optimum regime, with the least toxic ctyoprotectants, consisted of 1M Me2SO for 15 min and a combination of 15% PEG(w/v) + 3M PG + 2M Me2SO for 3 min, with the jelly coat intact, followed by vitrification. This gave a survival percentage of 87.6% immediately after vitrification. Methods designed for cryopreservation of fish embryos make a good starting point for cryopreservation of the embryos of amphibian.