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Background: Metaldehyde is a toxic pesticide used mainly as a molluscicide, responsible for intoxication and deaths in both humans and animals. Accidental exposure to metaldehyde in dogs is considered rare, but severe. Data concerning clinical and veterinary forensic toxicology are largely incomplete, especially regarding case reports in dogs. The present work reports a complete and detailed description of a case from the history, clinical evolution, pathological exams and toxicological diagnosis in an accidental case of metaldehyde poisoning in dog., Case Presentation: An eleven-month-old, 3.0 kg, male German Spitz was presented for emergency care with acute vomiting and seizures 3 hours after suspected accidental ingestion of commercial molluscicide containing 3% metaldehyde (Lesmax®). The animal was in lateral recumbency and showed stuporous mentation, salivation, tonic-clonic status epilepticus, systemic tremors, bilateral miosis, absent palpebral, corneal, oculovestibular and gag reflexes, severely depressed spinal reflexes, dyspnea and tachycardia. Despite treatment, the patient progressed to comatose mentation and died. Necropsy examination revealed discrete lesions in the liver and central nervous system, while stomach examination revealed content of feed, activated charcoal and blue-green granules, compatible to the commercial formula of metaldehyde. Histology examination revealed extensive hemorrhage and severe centrolobular necrosis of the liver and tumefaction of Kupfer cells. Brain samples showed discrete hemorrhage and hyperemia. In order to confirm the diagnosis, samples from feces, stomach content, spleen, liver, heart, kidneys and brain were submitted gas chromatography analysis. Results confirmed the presence of metaldehyde in all samples. We describe clinicopathological abnormalities of a fatal case of metaldehyde poisoning in a dog, as well as postmortem diagnosis using gas chromatography., Conclusion: Metaldehyde poisoning is rarely reported, since the diagnosis is often difficult and the notifications scarce. To our knowledge, this is the first report describing clinical signs, pathological findings and chromatographic diagnosis. This report aims to contribute to the understanding of the pathogenesis of metaldehyde intoxication, to further explore veterinary forensic toxicology diagnosis.

Metaldehyde is a molluscicide and the active ingredient in formulated slug pellets used for the protection of crops. Due to its mobility in the environment it is frequently found in river catchments, often at concentrations exceeding the EU Drinking Water Directive limit of 100 ng L-1 for a single pesticide. This presents a major problem for water companies in the UK where such waters are abstracted for production of potable drinking water supplies. Therefore, it is important to understand the sources, transport and fate of this emerging pollutant of concern in the aquatic environment. We monitored metaldehyde in two contrasting river catchments (River Dee (8 sites) and River Thames (6 sites)) over a twelve month period that coincided with the agricultural application period of the molluscicide. Spot samples of water were collected typically weekly or fortnightly. Chemcatcher® passive samplers were deployed consecutively every two weeks. At the River Dee, there was little variability in the concentrations of metaldehyde (<10-110 ng L-1) measured in the spot samples of water. The Chemcatcher® gave similar time-weighted average concentrations which were higher following increased rain fall events. At the River Thames, concentrations of metaldehyde varied more widely (<9-4200 ng L-1) with several samples exceeding 100 ng L-1. Generally these concentrations were reflected in the time-weighted average concentrations obtained using the Chemcatcher®. Both monitoring techniques gave complementary data for identifying input sources, and in the development of catchment management plans and environmental remediation strategies.

The application of metaldehyde to agricultural catchment areas to control slugs and snails has caused severe problems for drinking water supply in recent years. In the River Thames catchment, metaldehyde has been detected at levels well above the EU and UK drinking water standards of 0.1 μg l -1 at many sites across the catchment between 2008 and 2015. Metaldehyde is applied in autumn and winter, leading to its increased concentrations in surface waters. It is shown that a process-based hydro-biogeochemical transport model (INCA-contaminants) can be used to simulate metaldehyde transport in catchments from areas of application to the aquatic environment. Simulations indicate that high concentrations in the river system are a direct consequence of excessive application rates. A simple application control strategy for metaldehyde in the Thames catchment based on model results is presented.

Objective: To determine the contributions of main chemical compositions of extracts of Eucalyptus camaldulensis represented by GC/MS elute peaks to the molluscicidal activities, and explore a shortcut of looking for the effective components from natural products., Methods: E. camaldulensis leaves were collected consecutively in 12 months at the same place, extracted with dichloromethane, analyzed by GC/MS, and their LC50(s) of molluscicidal activities were tested according to the method recommended by WHO. The correlation of the main components in 12 extracts and their molluscicidal activities were analyzed by the grey relative correlation analysis model with software GTMS 3.0., Result: All the dichloromethane extracts of eucalyptus leaves showed excellent molluscicidal activities with the highest LC50 of 0.257mg/L and 0.242mg/L for the samples in June and July and the lowest LC50 of 6.802 mg/L and 5.406 mg/L in December and January respectively. The structures of 16 main chemical components were elucidated by GC/MS and NIST Mass Spectral Library, most of which were monoterpenes and sesquiterpenoids. The gray correlation coefficients with activity were all over 0.5, the first five over 0.9 were 4,4, 8-Trimethyltricyclo [6.3.1.0 (1,5) ]dodecane-2,9-diol, (-)-Spathulenol, a structural isomer of (-)-Spathulenol, Eucalyptol and Ledol., Conclusion: The most main ingredients in the dichloromethane extracts of E. camaldulensis leaves show good correlations with the molluscicidal activity, which suggests that the molluscicidal role is synergistically played by the multiple components together.

Chlorothalonil concentrations exceeding acute toxicity levels for certain organisms have been measured in surface water discharge events from managed turf watersheds. The duration of exceedence and the timing of these events related to precipitation/runoff and time since application, however, have not been explored. Chlorothalonil concentrations were measured from discharge waters draining a managed turf watershed in Duluth, Minnesota, USA, between 2003 and 2009. The median chlorothalonil concentration was 0.58 µg/L. Approximately 2% of all measured concentrations exceeded the 7.6 µg/L median lethal concentration (LC50) acute toxicity level for rainbow trout. One-twentieth the LC50 concentration, equivalent to the level of concern (0.38 µg/L) for endangered species, was exceeded 31% of the time during the present study. The concentrations that exceeded the LC50 threshold were associated with eight rainfall/runoff events. Low dose exposures are a more important biological concern than acute occurrences. Exceedence concentrations associated with acute effects were significantly (p < 0.05) correlated to time since application and were measured only in the fall following extensive application. A conflict exists between the transportability of chlorothalonil as suggested by its chemical properties and the data collected in the present study. With respect to course-wide golf course application, avoiding application until after the major autumn rainfall period but before the first snow coverage is recommended to reduce occurrence of chlorothalonil concentrations that exceed toxic levels associated with acute and chronic levels of concern., (Copyright © 2012 SETAC.)

The present work describes the development of an analytical method for the determination of methiocarb and its degradation products (methiocarb sulfoxide and methiocarb sulfone) in banana samples, using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure followed by liquid chromatography coupled to photodiode array detector (LC-PAD). Calibration curves were linear in the range of 0.5-10 mg L⁻¹ for all compounds studied. The average recoveries, measured at 0.1 mg kg⁻¹ wet weight, were 92.0 (RSD = 1.8%, n = 3), 84.0 (RSD = 3.9%, n = 3), and 95.2% (RSD = 1.9%, n = 3) for methiocarb sulfoxide, methiocarb sulfone, and methiocarb, respectively. Banana samples treated with methiocarb were collected from an experimental field. The developed method was applied to the analysis of 24 samples (peel and pulp) and to 5 banana pulp samples. Generally, the highest levels were found for methiocarb sulfoxide and methiocarb. Methiocarb sulfone levels were below the limit of quantification, except in one sample (not detected).

Pentachlorophenol (PCP) has been widely used for killing snails in areas of China where schistosomiasis is epidemic. With the re-emergence of schistosomiasis, the warranted production and consumption of PCP has inevitably resulted in persistent environmental contamination by it and its impurities, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). This study aimed to evaluate the contamination status and human burden of PCP and its impurities (PCDD/Fs) in China, considering the previous epidemic and re-emergence of schistosomiasis. We searched studies relevant to PCP occurrence in the environment and in humans in China. Data on snail elimination areas were included to estimate PCP consumption. Relevant publications were analyzed to distinguish PCDD/Fs contamination from PCP usage. PCP contamination was detected ubiquitously in various environmental media and in human samples; environmental levels were generally low, with the exception of some hot spots. In schistosomiasis-epidemic areas, there were significantly higher PCP levels in the environment and in humans than in control areas. Spatial disparities indicated the consistency between serious schistosomiasis epidemic areas and hot spots of PCP contamination. The data suggest an increased trend in PCP contamination of the environment. Specific PCDD/Fs contamination from PCP usage existed even at low environmental levels. The occurrence of PCP in the environment and in humans positively correlated with the epidemic of schistosomiasis. Thyroid-disrupting effects and cancer risk caused by PCP and PCDD/Fs even at low environmental levels in China's schistosomiasis-epidemic areas are of concern., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A high performance liquid chromatographic (HPLC) method was established for the analysis of niclosamide ethanolamine residue in rice and paddy field. The paddy water and plant were extracted with alkaline ethylacetate, while the paddy soil, rice husk and unpolished rice were first extracted with alkaline ethanol, and then with ethylacetate. The extracts were then cleaned-up by a Florisil column and detected by high performance liquid chromatography with an ultraviolet detector (UVD) on a Welchrom C18 column (250 mm x 4.6 mm, 5 microm). The calibration curve showed good linearity from 0.01 mg/L to 10.00 mg/L with the correlation coefficient more than 0. 999 8. The average recoveries of this method were from 93.47% to 100.9% with the relative standard deviations of 1.46% - 5.82% at the spiked levels of 0.01 - 5.00 mg/kg. This method is fast, simple, sensitive, reproducible and practical for the determination of niclosamide ethanolamine residue in paddy fields, and can meet the requirement of the determination of pesticide residues.

The dissipation of metaldehyde on cabbage and in soil was studied and half-life (DT(50)) was estimated in a field study carried out at three different locations. Metaldehyde was sprayed on cabbage at 937.5 and 1406.25 ga.i.ha(-1) for residue study and 1,875 ga.i.ha(-1) for dissipation study in cabbage and soil. Samples of cabbage and soil for dissipation experiment were collected at 0, 1, 2, 3, 5, 7, 14 and 21 days after treatment. For residue studies, cabbage and soil samples were sampled at 5, 7 and 10 days after treatment. Quantification of residues was done by LC-MS/MS. The DT(50) of metaldehyde in cabbage and soil were 0.48-1.61 days and 0.75-1.02 days, respectively, when applied at 2 times of the recommended high dosage. Residues of metaldehyde in cabbage were all below the maximum residue levels of 1.0 mg kg(-1) at both recommended high dosage and 1.5 times the recommended high dosage., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The biophenolic fraction was characterized in olive mill waste (OMW) obtained as a by-product from processing of Mission and Frantoio olive fruit. OMW produced from the Mission fruit contained higher total phenol content. Individual biophenols with the exception of verbascoside and a hydroxytyrosol-secoiridoid were also present at higher concentrations in the OMW produced from Mission cultivar. Antioxidant activities were measured in aqueous (DPPH) and emulsion (BCBT) systems. The Frantoio extract was more active than the Mission extract in the DPPH assay - EC(50) values were 28.3+/-1.7 ppm and 34.7+/-1.7 ppm, respectively. Activities were reversed in the BCBT, with the Mission extract (EC(50) 60.6+/-2.3 ppm) more potent than the Frantoio extract (EC(50) 79.9+/-2.0 ppm), and this may be related to the more lipophilic nature of the Mission extract. Both extracts showed broad spectrum antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa; whereas individual biophenols (hydroxytyrosol, luteolin, oleuropein) showed more limited activity. Molluscicidal activity was measured against Isidorella newcombi and LD(50) values were 424 ppm and 541 ppm for Mission and Frantoio extracts, respectively. The results suggest that OMW may be utilised as a source of bioactive compounds.

Imposex was found in the Arctic whelk Buccinum finmarkianum at several marine stations off Thule Air Base, an US military facility in Northwest Greenland. This indicates a widespread contamination with the antifouling agents, tributyltin (TBT) or triphenyltin (TPhT) in the area, but such contamination was not supported by the organotin analyses in sediments, whelks and clams, which in general was below the analytical detection limit. Organotin concentrations above the detection limit were found only at one station close to a quay, where the highest frequency of imposex also occurred. This suggests that imposex in B. finmarkianum is a biomarker of TBT more sensitive than the detection limits, which the analytical chemistry could achieve in this study.

The bark of Croton campestris provided three furano-clerodane named, respectively, velamone, velamolone acetate and velamolone. Fractions containing these diterpenoids were investigated for their molluscicidal activity against Bulinus truncatus, one of the aquatic snail vectors of schistosomiasis. A dichloromethanic extract of root barks, rich in furano-clerodane and molluscicidal at 20ppm was promising as natural molluscicide. Enriched fraction with velamone gave 80% mortality from 25ppm, while its LD(100) was at 50ppm. The LD(80) was ca. at 45ppm, while LD(100) was at 60ppm for the enriched fraction containing velamolone acetate. The velamolone-enriched fraction was less efficient and gave a mortality of 90% at 90ppm. The pure compounds, velamone and velamolone acetate were active at 100% at 3 and 6ppm, respectively. Velamolone showed a molluscicidal activity at 20ppm.

Tributyltin (TBT) was detected in all 24 surface sediment (top 2 cm) samples collected from Coddington Cove, Newport, RI. TBT surface sediment concentrations ranged from 32 to 372 ng Sn/g with a mean concentration of 146 ng Sn/g. Analyses of selected core sections detected TBT in at least the top 18 cm at all 7 stations where cores were collected. No consistent TBT concentration trends with depth for these cores suggest mixing is an important process in the sediment column. In one core (station 28), TBT was found in the 76-86 cm section at a concentration of 141 ng Sn/g; thus sediments are a significant sink for TBT. However, sediment mixing processes can enhance releases of bioavailable TBT. Mussels, clams and fish from Coddington Cove contain TBT at concentrations ranging from 9.2 to 977 ng Sn/g. TBT concentrations in lobsters were below the detection limit (<6 ng Sn/g). Based on available screening criteria, TBT concentrations in Coddington Cove sediment is likely to be having an adverse effect on the biota at some locations.

Current regulatory risk assessment procedures only assess the impact of antifouling paint biocides that are released through leaching from a painted surface. Hull cleaning activities can lead to particles of antifouling paint containing biocides to enter the environment. Comparative pseudo-first order anaerobic degradation rate constants and half-lives were determined for a selection of common antifouling paint booster biocides, their degradation products, and associated with paint particles. Anaerobic half-lives of <0.5 days were calculated for chlorothalonil, dichlofluanid, and SeaNine 211, between 1 and 3 days for DCPMU and DCPU, between 14 and 35 days for diuron and CPDU, and over 226 days for GS26575 and Irgarol 1051. Increased persistence was observed when the compounds were introduced to sediments associated with antifouling paint particles. When present as antifouling paint particles, an increased half-life of 9.9 days for SeaNine 211 and 1.4 days was calculated for dichlofluanid, no significant degradation was observed for diuron. It is suspected that this is due to much of the biocide being initially bound within the matrix of the paint particle that is slowly released through dissolution processes into the sediment pore water prior to degradation. The release of booster biocides associated with paint particles into marinas has the potential to lead to their accumulation unless activities such as hull cleaning are strictly regulated.

The distribution of tributyltin (TBT) contamination in the subtidal zone of the waters between Denmark and Sweden was investigated in relation to major international shipping lanes. Sediment and different benthic molluscs were sampled in transects along and perpendicularly to the shipping lanes in the Sound (Øresund) and the Kattegat/Skagerrak region. The samples were analysed for TBT and its degradation products, dibutyltin (DBT) and monobutyltin (MBT), using GC-PFPD. In sediments, the TBT concentration ranged from <1 to 19 ng g(-1) dry weight (dw) with a strong correlation between the TBT concentration and the organic fraction in sediment (r(2)=0.90) in the samples collected in the Sound, where the highest concentrations were found. This relationship was not observed in the samples from the Kattegat because the TBT concentration in most sediment samples was below the limit of detection. In the molluscs, TBT and its degradation products were detected in all samples from the entire area with concentrations ranging from 8.1 ng g(-1) dw in Buccinum undatum to 1316 ng g(-1) dw in Nuculana pernula. The deposit-feeding bivalve N. pernula was found to have a particularly high accumulation potential for TBT. In addition, a strong correlation between TBT concentrations in sediment and N. pernula was found. Therefore this species seems to be an ideal organism for monitoring sediment contamination. The TBT concentration in N. pernula was found to decrease gradually along the shipping lanes from the Sound, through the Kattegat and into the Skagerrak.

Organic booster biocides were recently introduced as alternatives to organotin compounds in antifouling products, after restrictions imposed on the use of tributyltin in 1987. In this study, the concentrations of three biocides commonly used as antifoulants, Irgarol 1051 (2-methylthio-4-tertiary-butylamino-6-cyclopropylamino-s-triazine), dichlofluanid (N-dichlorofluoromethylthio-N',N'-dimethyl-N-phenyl sulphamide) and chlorothalonil (2,4,5,6-tetrachloro isophthalonitrile) were determined in sediments from ports and marinas of Greece. Piraeus (Central port, Mikrolimano and Pasalimani marinas), Thessaloniki (Central port and marina), Patras (Central port and marina), Elefsina, Igoumenitsa, Aktio and Chalkida marinas were chosen as representative study sites for comparison with previous monitoring surveys of biocides in coastal sediments from other European countries. Samples were collected at the end of one boating season (October 1999), as well before and during the 2000 boating season. All the compounds monitored were detected at most of sites and seasonal dependence of biocide concentrations were found, with maxima during the period June-September, while the winter period (December-February) lower values were encountered. The concentrations levels ranged from 3 to 690 ng/g dw (dry weight). Highest levels of the biocides were found in marinas (690, 195 and 165 ng/g dw, for Irgarol, dichlofluanid and chlorothalonil respectively) while in ports lower concentrations were observed. Antifouling paints are implicated as the likely sources of biocides since agricultural applications possibly contributed for chlorothalonil and dichlofluanid inputs in a few sampling sites.

The seas surrounding Singapore are principally utilized by the shipping industry but are now also increasingly used for a variety of other purposes, including desalination for supplies of drinking water and intensive aquaculture of food fish. While stringent environmental pollution standards are in place for industrial effluents, there is currently no legislative control over pollution from anti-fouling paints in Singapore. In this study, the concentrations of toxic antifouling agents tributyltin (TBT), triphenyltin (TPhT) and Irgarol-1051 (2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine) were determined from seawater obtained from 26 locations along and off the coast of Singapore in October and November 2000. These compounds were isolated by liquid-liquid extraction derivatized under controlled microwave heating and quantified by gas chromatography-mass spectrometry. TBT concentrations in seawater ranged between 0.43 and 3.20 microg 1(-1) with a mean value of 1.40 +/- 0.60 micro 1(-1). The mean values of DBT and MBT were 1.07 +/- 0.80 microg 11(-1) and 0.34 +/- 0.50 microg 1(-1) respectively, while TPhT concentrations of up to 0.40 microg 1(-1) were found. Monophenyltin and diphenyltin were not detected in all samples analysed. Irgarol-1051 was found to be present at concentrations of between 3.02 microg 1(-1) and 4.20 microg 1(-1) in seawater with a mean value of 2.00 +/- 1.20 microg 1(-1).

A compilation of the results of a monitoring program of the recently used antifouling pesticides diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea), Irgarol 1051 (2-methylthio-4-tertiary-butylamino-6-cyclopropylamino-s-teiazine), seanine 211 (4,5-dichloro-2-n-octyl-4-isothazolin-3-one), chlorothalonil (2,4,5,6-tetrachloro-isophthalonitrile), dichlofluanid (N'-dimethyl-N-phenylsulphanamide), TCMTB ((2-thiocyanomethylthio) benzothiazole), and three degradation products demethyldiuron (3-(3,4-dichlorophenyl)-1-methylurea),3,4-dichlorophenylurea and 2-methylthio-4-tert-butylamino-s-triazine (Irgarol degradation product) that was carried out between April 1996 and February 2000 in enclosed seawaters from Catalonia and Almería (Spanish Mediterranean coast) is reported. Nine points were sampled along the Catalan coast: Barcelona Olympic port, Masnou, Blanes, Sant Carles de la Ràpita, Tarragona, Cambrils and Salou marinas as well as the Cambrils and Tarragona fishing harbors and in marinas and ports from Almeria: Aguadulce port, Almería port, Almerimar fishing harbour and Almerimar marina. The analytical methodologies were based on Solid Phase Extraction followed by liquid chromatography (LC) or gas chromatography (GC) coupled to a mass spectrometry (MS) or -Diode Array Detector. The main pollutants found in the sampled points were diuron and Irgarol 1051 that were detected at concentrations up to 2.19 micrograms l-1 and 0.33 microgram l-1, respectively. On the other hand, seanine 211 was found at the highest concentration (up to 3.7 micrograms l-1) during the summer of 1999. Low concentrations of dichlofluanid and the above mentioned degradation products were detected for the first time in the Spanish coasts. Chlorothalonil, TCMTB were not found at concentrations higher than 1 and 20 ng l-1 respectively which were the limit of determination (LOD) of the method for these compounds. In general the contamination at the different marinas is higher at the end of spring and in summer where the boating activity is also higher. This paper shows for the first time that the contamination by the new antifouling pesticides in Spanish coastline, basically marinas and fishing harbours, is permanent along the whole calendar year. So, preventive actions by the harbour authorities will be needed in the near future in order to monitor and control the levels and effects of the new antifouling biocides in the marine environment.

In this paper Uv spectrophotometry was used to determine Niphensamide. In this method, 372 +/- 1 nm was selected as a criterion for quantitative determination, and the absorptivity. E1 cm 1% = 556. The results indicated that a better linear-relationship between the absorbance and the concentration of the sample. When the concentration was ranged from 0.5 mg.L-1 to 40 mg.L-1, the correlation coefficient was 0.9999, and the mean rate of recovery reached 99.8%.

In this work, we have studied the molluscicidal activity of different extracts obtained from Cotula cinerea and Quercus lusitania var. infectoria galls. The hydroalcoholic extract of Cotula cinerea, acetonic extract and gallotanin of Quercus infectoria galls have presented high activity against Bulinus truncatus. The hydroalcoholic extract of Cotula cinerea was fractionated by chromatography on silica gel column. We have isolated two very active fractions at concentrations respectively of 52.5 and 27.5 ppm.

An HPLC method for the quantitative determination of Niphensamide in pesticide powder was developed. Column:Micropak-CH 5 microns (300 mm x 4.0 mm i.d.), mobile phase: CH3OH-H2O(1:1), detector: UV 254 nm, flow rate: 0.7 mL/min, column temperature: 25 degrees C. Under the above conditions, Niphensamide and other components were separated from each other. The method is simple, rapid, sensitive and accurate.

A hemolytic method was developed for the quantitative determination of oleanane saponin (Endod-S) in Phytolacca dodecandra (Phytolaccaceae), a plant with potent molluscicidal properties. A chemical method based on thin-layer chromatography (TLC) was used as a control for comparison with a hemolysis test. Standard curves for calibration of both tests of Endod-S gave high correlation coefficients. The hemolysis method gave a correlation coefficient of 0.98 for saponin (Endod-S) levels ranging from 1.6 to 4.2 mg/l. The TLC method gave a correlation coefficient of 0.99 for saponin levels above 1.5 micrograms. Due to the action of saponins on erythrocytes, the hemolysis method could not be used at levels below 1.6 and above 4.2 mg/l. Similarly, sample size limited TLC quantitation of these saponins at levels below 1 microgram. Both the TLC and the hemolysis methods on identical Endod-S water samples gave comparable results at saponin levels between 2 and 6 mg/l. A snail bioassay showed that the LC50 and the LC90 concentrations of Endod-S to the snail Biomphalaria glabrata (albino) were 2.57 and 2.92 mg/l respectively. These values fell in the standard curve range for the hemolysis method thus indicating that the hemolysis method is of practical value for testing Endod-S concentrations that would actually be used in field applications for snail control. The hemolysis method is less expensive than TLC and can be easily adapted to field conditions.

Under field conditions molluscicides can undergo hydrolysis to compounds that have no molluscicidal action. In a continuation of laboratory studies on hydrolysis, investigations have been made on N-tritylmorpholine (Shell WL 8008). The rate of hydrolysis increases with decreasing pH, being rapid below pH 7. An emulsion prepared from an emulsifiable concentrate was found to be much more stable than an aqueous solution of the compound, presumably because of the protective effect of oil droplets. The stability of the compound as a wheat-germ bait was also studied; there was about a 10% decrease in concentration in 22 hours. The portion that dissolved in the water was almost completely hydrolysed, whereas that remaining in the bait was much less so.

A colorimetric method has been developed for the determination of the molluscicide N-tritylmorpholine (Frescon, WL 8008) in water. The method is based on the production, from N-tritylmorpholine in strong acid, of the typical yellow colour of the tritylcarbonium ion.Two procedures are recommended for field use, neither of which distinguishes between N-tritylmorpholine and its hydrolysis product triphenylcarbinol (triphenylmethanol). A more precise laboratory procedure is described, by means of which both N-tritylmorpholine and triphenylcarbinol can be determined separately.

The fate of the molluscicide trifenmorph (N-tritylmorpholine) following its use in irrigation systems to control the intermediate hosts of schistosomes was studied by laboratory and field experiments. Laboratory studies with (14)C-trifenmorph indicated that bean plants did not take up detectable residues when the soil in which they were grown was irrigated with water containing trifenmorph in concentrations likely to occur in the field. These laboratory studies have been complemented by field irrigation studies of growing crops in southern Africa and the Sudan. Residues of trifenmorph and its breakdown product triphenylmethanol could not be detected in the crops and the limit of detectability was 0.01-0.02 ppm. These results indicate that residues are not likely to be present in irrigated crops following the treatment of the irrigation water systems with trifenmorph.

The molluscicide N-tritylmorpholine (Frescon, WL 8008) is likely to be applied to flowing water systems in bilharziasis control programmes. The treated water in irrigation systems will sometimes be applied to growing crops, such as rice, and the nature of the terminal residues of N-tritylmorpholine in rice has therefore been investigated.Crops were grown under greenhouse conditions in soil treated with water containing (14)C-and(3)H-N-tritylmorpholine, using dosage levels very much greater than those that will generally be used in the field. The major radiocomponent in the rice plants was triphenylcarbinol (triphenylmethanol), together with smaller amounts of unchanged N-tritylmorpholine and o-, m-, and p-hydroxytriphenylcarbinol. The hydroxytriphenylcarbinols were present as the free hydroxy compounds and as plant conjugates.Residues of the parent molluscicide and its break-down products are not considered likely to present a toxic hazard to animals or men that eat the crops.