Effect of dielectric barrier discharge plasma on the degradation of malathion and chlorpyrifos on lettuce.

BACKGROUND: Pesticides have been widely used to control pests on agricultural products in China, and large amounts of pesticide residues have caused a serious threat to human health. Thus, developing a high-efficiency pesticide degradation method for fresh vegetables represents a great challenge. The present study investigated the effects of dielectric barrier discharge (DBD) plasma on the degradation of malathion and chlorpyrifos in aqueous solutions and on lettuces. RESULTS: DBD treatment significantly degraded malathion and chlorpyrifos in water and on lettuce. After cold plasma treatment at 80 kV for 180 s, the degradation efficiency of malathion (0.5 µg mL-1 ) and chlorpyrifos (1.0 µg mL-1 ) in aqueous solutions reached 64.6% and 62.7%, respectively. The degradation intermediates were explored by HPLC-mass spectrometry and the DBD plasma degradation pathways of malathion and chlorpyrifos were proposed. There was no significant damage to the quality of lettuces, including color and chlorophyll content, after plasma treatment. Ascorbic acid decreased significantly during long-term treatment with DBD plasma. To ensure the quality of lettuces during processing, the treatment time was shortened to 120 s. Under this condition, the degradation efficiency of malathion (0.5 mg kg-1 ) and chlorpyrifos (1.0 mg kg-1 ) on lettuces was found to be 53.1% and 51.4%. More importantly, we noted that cold plasma treatment significantly inactivated the microorganisms on lettuces. CONCLUSION: The results of the present study show that cold plasma is an effective and safe method for the degradation of organic pesticide residues on fresh vegetables at the same time as retaining the original quality. © 2020 Society of Chemical Industry.

Loss of effectiveness of protective clothing after its use in pesticide sprays and its multiple washes.

Protective clothing is used as a barrier against pesticides when working with agricultural sprays. The aim of this study was to evaluate the pesticide penetration, retention, and repellence of the material and seams of a whole-body protective garment used by applicators of pesticides. The efficiency of the material and seams of the whole-body garment were determined for its classification as proposed by ISO 27065 (ISO, 2011). The evaluation method used was the pipette test of ISO 22608. The efficiency of the material and seams of the garment (100% cotton) were tested by contamination with formulations of Roundup Original® SL; Nufos EC® and Supera SC®. The presence of the seams in the protective clothing reduced its efficiency in the control of dermal exposure, except when protecting against the Supera SC® formulation. The number of washes and uses affected the efficiency of the material and seams of the garment. The type of formulation interfered significantly in the penetration of pesticides into the material and seams. Thus, the laboratory efficiency assessment of protective clothing is necessary to determine what types of formulations and use conditions are appropriate for workers.

Occurrence and fate of pesticides in the Argentine stretch of the Paraguay-Paraná basin.

The Argentine stretch of the del Plata basin crosses regions devoted to extensive and intensive agriculture mostly with chemical pest control. The utilization of pesticides in the region has increased 900% in the last two decades associated with the introduction of biotech crops and direct-seeding techniques. Our objective was to study the occurrence, concentration, and fate of pesticides in surface water and bottom sediments of the principal tributaries and main watercourse of the Paraguay-Paraná River. We sampled 22 sites in the distal positions of the main affluents and main watercourse of the Paraná and report here results from two monitoring campaigns (2010-2012). Surface water and bottom sediments were analyzed according to standardized methods by matrix-solid-phase dispersion and liquid-liquid extraction, respectively. Twenty-three pesticide compounds were analyzed by gas chromatography. The results from both campaigns indicated a generalized but variable distribution in the concentrations detected throughout the basin. The ranges of total measured pesticide concentrations in water and sediments were, respectively, 0.004-6.62 µg/l and 0.16-221.3 µg/kg dry weight. Endosulfans, cypermethrin, and chlorpyrifos were ubiquitous compounds in both environmental compartments and quantitatively the most relevant. All concentrations detected in water were over the recommended guidelines for the protection of aquatic biota. The partitioning indicated a higher affinity for the sediments. Agricultural activity is the source of pesticide-pollution loads, transported by tributaries that reach the main watercourse and alter the quality of the aquatic ecosystem.

Current view of zinc as a hepatoprotective agent in conditions of chlorpyrifos induced toxicity.

Human population bears the brunt of deadly hepatotoxic, neurodegenerative, behavioural and various other developmental disorders due to pesticide toxicity through environmental or occupational exposures. The application of pesticides to control pests in land and water has posed potential health hazards to live stock and wildlife including fishes, mammals, birds and humans. Therefore, various scientific approaches are being considered to tackle the problem of pesticide poisoning especially in developing economies. The role of essential trace elements as the promising and efficient preventive prophylactic agents without any toxicity and side effects in attenuating the adverse effects caused by pesticides, have been reported by various scientists, the world over. In this perspective, zinc, a key constituent of more than 300 mammalian enzymes and many transcription factors has proved its protective potential in various models of animal toxicity. The hepato-protective potential of zinc has been proved during various toxic states including pesticide toxicity. However, zinc warrants further examination with regard to documentation of specific molecular pathways to establish the exact mechanisms for zinc-mediated protection during pesticide toxicity.

Chlorpyrifos-treated crops in the vicinity of surface water contamination in the San Joaquin Valley, California, USA.

Due to frequent contamination of streams in the San Joaquin Valley, California, USA, with the insecticide chlorpyrifos, researchers are working to identify crop-specific management practices that will reduce the offsite movement of this compound into surface waters. To guide this effort, crops treated with chlorpyrifos in the vicinity of contaminated streams were identified; walnut, alfalfa, and almond were the primary crops identified. Use was higher on walnut and almond, but due to irrigation practices offsite movement in surface runoff may be more likely from alfalfa. Based on these findings, development of management practices to reduce off-site movement of chlorpyrifos in irrigation runoff from treated alfalfa fields is recommended.

Betulinic acid protects against cardiotoxicity of the organophosphorus pesticide chlorpyrifos by suppressing oxidative stress, inflammation, and apoptosis in rats.

The widespread application of organophosphorus (OP) pesticides can affect the environment as well as the animal and human health. Chlorpyrifos (CPF) is a broad-spectrum OP pesticide used in agriculture and can cause several toxic effects in which oxidative stresses and inflammation play a key role. This study aimed to evaluate the protective activity of betulinic acid (BA), an antioxidant and anti-inflammatory pentacyclic triterpene, against CPF cardiotoxicity in rats. The rats were divided into four groups. CPF (10 mg/kg) and BA (25 mg/kg) were orally administered for 28 days, and blood and heart samples were collected. CPF-administered rats showed an increase in serum cardiac troponin I (cTnI), creatine kinase (CK)-MB, and lactate dehydrogenase (LDH), accompanied with multiple myocardial tissue alterations. Lipid peroxidation (LPO), nitric oxide (NO), nuclear factor-kappaB (NF-κB), interleukin (IL)-6, IL-1ß, and tumor necrosis factor (TNF)-α were increased, and antioxidant were decrease in CPF-administered rats. BA ameliorated cardiac function markers and tissue injury, decreased LPO, NO, NF-κB, and proinflammatory cytokines, and increased antioxidants. In addition, BA decreased proapoptosis markers, and increased B-cell lymphoma (Bcl)-2, IL-10, Nrf2, and HO-1 in the heart of CPF-treated rats. In conclusion, BA protected against cardiotoxicity in CPF-administered rats by mitigating oxidative stress, inflammation, and apoptosis, and enhanced Nrf2 and antioxidants.

Chlorpyrifos and neurodevelopmental effects: a literature review and expert elicitation on research and policy.

BACKGROUND: Organophosphate pesticides are widely used on food crops grown in the EU. While they have been banned from indoor use in the US for a decade due to adverse health effects, they are still the most prevalent pesticides in the EU, with Chlorpyrifos (CPF) being the most commonly applied. It has been suggested CPF affects neurodevelopment even at levels below toxicity guidelines. Younger individuals may be more susceptible than adults due to biological factors and exposure settings. METHODS: A literature review was undertaken to assess the evidence for CPF contributing to neurodevelopmental disorders in infants and children. Other literature was consulted in order to formulate a causal chain diagram showing the origins, uptake, and neurological effects of animal and human exposure to CPF.The causal chain diagram and a questionnaire were distributed online to scientific experts who had published in relevant areas of research. They were asked to assess their confidence levels on whether CPF does in fact contribute to adverse neurodevelopment outcomes and rate their confidence in the scientific evidence. A second questionnaire queried experts as to which kind of policy action they consider justifiable based on current knowledge. In a special workshop session at the EuroTox congress in Dresden in 2009 the results of both questionnaires were further discussed with invited experts, as a basis for a policy brief with main messages for policy makers and stakeholders. RESULTS: Most experts who responded to the first questionnaire felt that there was already enough evidence to support a ban on indoor uses of CPF in the EU. However, most felt additional research is still required in several areas. The responses from the first questionnaire were used to formulate the second questionnaire addressing the feasibility of government action. In turn, these expert participants were invited to attend a special session at the EuroTox congress in Dresden in 2009. CONCLUSIONS: Some of the evidence that CPF contributes to neurodevelopmental disorders is still disputed among experts, and the overall sense is that further research and public awareness are warranted. There have been campaigns in North America making the potential exposure concerns known, but such information is not widely known in the EU. The ability of government action to produce change is strongly felt in some quarters while others believe better knowledge of consumer use trends would have a greater impact.

Efficiency of Gum Rosin-Coated Personal Protective Clothing to Protect against Chlorpyrifos Exposure in Applicators.

An ideal theoretical model for personal protective clothing (PPC) is to protect wearers from external workplace hazards while meeting certain ergonomic requirements. This study aims to compare the efficiency of different personal protective clothing in its protection against chlorpyrifos, including gum rosin-coated PPC, commercial PPC (Tychem® coverall), and everyday clothing, during application under field conditions. Perception of discomfort and physiological effects after wearing PPC were also investigated. Thirty-one applicators were invited and consented to participate in the study. The study established that the median percentage of chlorpyrifos protection efficiency was 90.7% for commercial PPC, 89.2% for gum rosin-coated PPC, and 76.5% for everyday PPC. When the protection efficiency was compared among the different types of PPC, the percentage protection efficiency of gum rosin-coated PPC was not significantly different from that of commercial PPC. The percentage protection efficiencies of commercial PPC and gum rosin-coated PPC were significantly higher than that of everyday PPC. The major characteristics of gum rosin-coated PPC were water-repellency, breathability, low cost, and ease of manufacture. Therefore, this study suggests that gum rosin-coated PPC is a reasonable alternative PPC for farmers, particularly in low and middle-low-income countries and tropical climates, to protect against pesticides while providing acceptable comfort.

Molecular characterization of monocrotophos and chlorpyrifos tolerant bacterial strain for enhancing seed germination of vegetable crops.

The main aim of this study is to investigate the toxicity of organophosphate (OPs) insecticides monocrotophos (MCP) and chlorpyrifos (CLS) on plant growth promoting (PGP) properties and seed germination of brinjal, tomato and okra vegetables inoculated by Microbacterium hydrocarbonoxydans (BHUJP-P1), Stenotrophomonas rhizophila (BHUJP-P2), Bacillus licheniformis (BHUJP-P3) and Bacillus cereus (BHUJP-P4). Maximum increase in microbial growth (52.6% & 47.9%) with enhanced EPS production (447.67 mg/ml & 75.00 mg/ml) was showed by BHUJP-P4 and BHUJP-P3 at 10× dose of MCP and CLS over control, BHUJP-2 and BHUJP-P1 respectively. Simultaneously, both strains recorded minimum reduction in PGP activities and seed germination at 3× dose of both insecticides as compared to BHUJP-2 and BHUJP-P1, respectively. Strains BHUJP-P3 and BHUJP-P4 showed 83 and 81% of monocrotophos degradation at 50 mg/kg concentration; 81 and 80% at 150 mg/kg concentration within 5days respectively. Concurrently, these strains BHUJP-P3 and BHUJP-P4 were recorded 53 and 90% of chlorpyrifos degradation at 50 mg/kg concentration; 49% and 87% at 100 mg/kg concentration within 72 h, respectively. The OPs insecticide degrading gene opdA and opd was found in strain BHUJP-P3 and BHUJP-P4, respectively. The multifarious biological activities of strain BHUJP-P3 and BHUJP-P4 showed maximum tolerance against insecticide, and minimum reduction in P-solubilisation, IAA, siderophore and HCN production for plant growth promotion and biological control under insecticide stress. Thus, these novel isolates may be used as biodegradation of organophosphate insecticide and plant growth promoting bacterial (PGPB) inoculum for enhancing seed germination of vegetables under stress insecticide. These novel strains will be environment friendly, socially acceptable and economically viable.

[About an insecticidal paint for controlling Triatoma infestans, in Bolivia]. / Sobre uma pintura inseticida para o controle de Triatoma infestans, na Bolívia.

Preliminary evaluations of an insecticidal paint based on diazinon, chlorpyrifos and pyriproxyfen in a micro-encapsulated formulation (Inesfly 5A IGR) have shown that it has effective and persistent activity against Triatoma infestans inside homes and in areas surrounding homes, in a highly infested region of the Bolivian Chaco. Furthermore, the evaluations have highlighted that the product presents good handling characteristics and gives a good appearance to houses and outhouses that have been treated, and that its acceptance among the population and the local sanitary authorities is excellent. This encourages new investigations and the use of the product on a larger scale and against other vector species for Chagas disease.

Novel insights in biopurification system for dissipation of a pesticide mixture in repeated applications.

A biopurification system based on the adsorption and degradation capacity of a biomixture to degrade a mixture of pesticides (atrazine, chlorpyrifos, iprodione; 50 mg kg-1 each) in repeated applications (0, 30, and 60 days) was evaluated. Tanks of 1 m3 packed with a biomixture (ρ 0.29 g mL-1) with and without vegetal cover were used. The biomixture contained soil, peat, and wheat straw in a proportion 1:1:2 by volume, respectively. Pesticide concentrations, biological activities (urease, phenoloxidase, and dehydrogenase), and microbial community changes (DGGE and qPCR) were evaluated periodically. Pesticide dissipation was higher in tanks with vegetal cover (> 95%) and no variation was observed after the three applications; contrarily, pesticide dissipation decreased in the tank without vegetal cover after each application. The presence of vegetal cover decreased the half-life of pesticides by at least twice. Biological activities were in general not affected by the application and reapplication of pesticides in the same treatment; however, they exhibited some differences between tanks containing and lacking the vegetal cover. High similarity between microbial groups (actinobacteria, bacteria, and fungi) was observed, suggesting no influence ascribable to the successive pesticide applications. The number of copies of bacteria and actinobacteria remained almost constant during the assay. However, the number of copies of fungi was significantly higher in the uncontaminated tank without vegetal cover.

Organophosphate insecticide exposure: A clinical consideration of chlorpyrifos regulation.

BACKGROUND AND PURPOSE: In March 2017, the Environmental Protection Agency (EPA) reversed course on a proposal to ban the agricultural use of the organophosphate (OP) insecticide chlorpyrifos (CPF). The purpose of this article is to examine the evidence leading to this controversial decision and provide clinically applicable health promotion guidance for nurse practitioners on CPF exposure and risk reduction measures. METHODS: Environmental Protection Agency documents on CPF regulation and corresponding research referenced within the EPA reports are reviewed. Evidence-based health promotion strategies obtained through PubMed, CINAHL, Center for Disease Control and Prevention, and National Institutes of Health sources are summarized. CONCLUSIONS: Available data suggest a potential association between CPF exposure and adverse neurodevelopmental outcomes. Particularly vulnerable populations are pregnant women, children younger than two years, and agricultural workers. There may be genetic variability in susceptibility to environmental toxins. IMPLICATIONS FOR PRACTICE: Because of the extensive use of the OP CPF in agriculture and other community-based settings throughout the United States, nurse practitioners should be knowledgeable of the evidence regarding CPF exposure and be prepared to provide health promotion guidance to patients in clinical practice. Nurse practitioners should also consider their role in advocacy for healthy environments and the protection of vulnerable populations as it relates to agricultural insecticide exposure.

Dermal exposure of applicators to chlorpyrifos on rice farms in Ghana.

Studies evaluating dermal exposure to pesticides among applicators in tropical countries have largely been conducted using the patch dosimetry and hand wiping/washing techniques. This study used the more accurate whole-body dosimetry technique to evaluate dermal exposure to chlorpyrifos among applicators on rice farms in Ghana. The exposure levels were plotted as Cumulative Probability Distribution (CPD). Total Dermal Exposure (TDE) of chlorpyrifos among the median exposed and the 5% highly exposed groups during a spray event were 24 mg and 48 mg, respectively. When these were converted as a percentage of the quantity of active ingredient applied (Unit Exposure, UE), UE values of 0.03% and 0.06% were found among the median exposed and the 5% highly exposed groups, respectively. Overall, the hands were the most contaminated anatomical regions of the applicators, both in terms of proportion of TDE (39%) and skin loading (13 µg/cm2). Also, the lower anatomical region was more contaminated (82% of TDE) compared to the upper anatomical region (18% of TDE). The levels of chlorpyrifos TDE among the applicators were found to be influenced by the quantity of insecticide applied and the height of the crops sprayed (p < 0.05). The pesticide UE data of the present study can be used to estimate the levels of dermal exposure under similar pesticide use scenarios among applicators. The findings of the present study suggest that protecting the hands and the lower anatomical regions with appropriate PPE may significantly reduce exposure among applicators.

An integrated vegetated ditch system reduces chlorpyrifos loading in agricultural runoff.

Agricultural runoff containing toxic concentrations of the organophosphate pesticide chlorpyrifos has led to impaired water body listings and total maximum daily load restrictions in California's central coast watersheds. Chlorpyrifos use is now tightly regulated by the Central Coast Regional Water Quality Control Board. This study evaluated treatments designed to reduce chlorpyrifos in agricultural runoff. Initial trials evaluated the efficacy of 3 different drainage ditch installations individually: compost filters, granulated activated carbon (GAC) filters, and native grasses in a vegetated ditch. Treatments were compared to bare ditch controls, and experiments were conducted with simulated runoff spiked with chlorpyrifos at a 1.9 L/s flow rate. Chlorpyrifos concentrations and toxicity to Ceriodaphnia dubia were measured at the input and output of the system. Input concentrations of chlorpyrifos ranged from 858 ng/L to 2840 ng/L. Carbon filters and vegetation provided the greatest load reduction of chlorpyrifos (99% and 90%, respectively). Toxicity was completely removed in only one of the carbon filter trials. A second set of trials evaluated an integrated approach combining all 3 treatments. Three trials were conducted each at 3.2 L/s and 6.3 L/s flow rates at input concentrations ranging from 282 ng/L to 973 ng/L. Chlorpyrifos loadings were reduced by an average of 98% at the low flow rate and 94% at the high flow rate. Final chlorpyrifos concentrations ranged from nondetect (<50 ng/L) to 82 ng/L. Toxicity to C. dubia was eliminated in 3 of 6 integrated trials. Modeling of the ditch and its components informed design alterations that are intended to eventually remove up to 100% of pesticides and sediment. Future work includes investigating the adsorption capacity of GAC, costs associated with GAC disposal, and real-world field trials to further reduce model uncertainties and confirm design optimization. Trials with more water-soluble pesticides such as neonicotinoids are also recommended. Integr Environ Assess Manag 2017;13:423-430. © 2016 SETAC.

Scopolamine treatment for severe extra-pyramidal signs following organophosphate (chlorpyrifos) ingestion.

BACKGROUND: The use of competitive inhibitors of acetylcholine other than atropine, for patients with organophosphate poisoning is controversial. Because scopolamine ability to cross the blood-brain barrier is better than that of atropine, it has been suggested that it should be used in patients with organophosphate poisoning who have central nervous system manifestations. CASE DESCRIPTION: A 17-year-old girl was admitted to the pediatric ward after ingesting chlorpyrifos as a suicidal attempt. She reported vomiting three times. She had no other symptoms for 12 hours and then over the course of 36 hours gradually developed extrapyramidal signs and became comatose. She was treated with intravenous scopolamine. Within 3 minutes the patient started to respond to verbal commands and answered simple questions rigidity subsided, and she was able to sit in bed. She was discharged after 4 days with no neurological sequelae. CONCLUSIONS: We suggest, that in patients with organophosphate poisoning who have mainly central nervous system toxicity scopolamine administration might be considered.

Aedes aegypti in a Texas coastal county as an index of dengue fever receptivity and control.

Since Galveston County, Texas, is one of the high risk areas for the reintroduction of dengue, we have maintained an Aedes aegypti surveillance program since 1977 by using ovitraps to determine the density and distribution of this species in 17 communities. A. aegypti adults were present primarily from May thrugh November, with higher positive ovitrap rates associated with periods of low rainfall. Larvae collected from six different communities, when compared with a standard, insecticide-susceptible strain exhibited only 2 X greater tolerance to malathion and chlorpyrifos. Similar results were obtained with malathion susceptibility tests of adults. Ultra-low volume malathion treatments of caged A. aegypti in a residential city block yielded good kills in the proximal but not the distal half of the block. Ovitraps in a two square-block area, treated with single pellets of chlorpyrifos, were less frequently positive and contained a smaller average number of eggs per trap than untreated traps in the surrounding area.

Experimental and field evaluations of two acaracides for control of I. pacificus (Acari: Ixodidae) in northern California.

Use of acaricides for the control of Ixodes pacificus (Cooley & Kohls), the vector of Lyme borreliosis in the western United States, can be a beneficial component in a program to reduce the morbidity of Lyme borreliosis in California. Three commercially available acaricides, carbaryl, chlorpyrifos, and diazinon, were evaluated in laboratory bioassays for their effectiveness against I. pacificus adults. Based on bioassay results, chlorpyrifos and carbaryl were selected for field evaluations. Chlorpyrifos demonstrated the lowest LD50 in the laboratory and the best overall control in the field trials. Chlorpyrifos and carbaryl provided effective control with a residual effect on adult ticks up to 7 wk after a single treatment. A field application timed to coincide with the highest period of adult questing activity proved effective in the control of I. pacificus in a Sierran foothill habitat. Judicious use of either of the acaricides evaluated may help to reduce adult tick densities in a peridomestic environment and thereby reduce the risk of human exposure to Lyme borreliosis and other tick-borne agents.

Twenty-four-hour urinary excretion of ten pesticide metabolites in healthy adults in two different areas of Italy (Florence and Ragusa).

The determination of pesticide metabolites in human biological fluids represents an important biomarker of exposure in the general population and exposed workers. In the frame of a prospective study, we measured the 24-h urinary excretion of 10 pesticide metabolites to evaluate non-occupational exposure to pesticides in the general population in two different areas in Italy. We collected 24-h urine samples from 69 healthy adults residing in Florence (Central Italy, n = 51) and Ragusa (Southern Italy, n = 18). The volunteers (25 males, 44 females; mean age 56 years) did not report any occupational exposure. We measured: six alkylphosphates, aspecific metabolites of organophosphorus pesticides [dimethylphosfate (DMP), dimethylthiophosfate (DMTP), dimethyldithiophosfate (DMDTP), diethylphosfate (DEP), diethylthiophosfate (DEDP), and diethyldithiophosfate (DEDTP)]; 3,5,6-trichloro-2-pyridinol (TCP), the main metabolite of chlorpyrifos; 3-phenoxybenzoic acid (3-PBA), a metabolite of pyrethroid insecticides; ethylenethiourea (ETU) a metabolite of ethylenebisdithiocarbamates; methamidophos (METH), an organophosphorus insecticide. We also measured PABA excretion as compliance marker (mean recovery 95%). Dimethylphosphates were found in detectable concentrations in the majority of samples (89.9%, 82.6% and 60.9% for DMP, DMTP and DMDTP, respectively). Urinary diethylphosphates (DEP, DETP, DEDTP) concentrations were above the detection limit in 80.9%, 61.8% and 27.5% of samples, respectively. TCP, 3-PBA and ETU were detected in 78.3%, 53.6% and 21.7% of samples, respectively. Methamidophos was detected in two samples (2.8%). The median number of metabolites detected in the same urine sample was 6 (range 0-9). Excretion levels were highest for alkylphosphates, particularly for DMTP (median: 142.6 nmol/day). Multivariate analysis showed statistically significant differences between these two groups of adults, with higher mean values of urinary excretion of alkylphosphates, TCP and ETU in Florence in comparison to Ragusa. Overall, a very high percentage of 24-h urine samples positive for several pesticide metabolites emerged, with higher levels of urinary daily excretion in subjects residing in the more urbanised area. Our results suggest that food monitoring programs should be supported by general campaigns aimed to reduce the use of pesticides in agriculture.

Fate of malathion and chlorpyrifos methyl in rough rice and milling fractions before and after parboiling and cooking.

Long-grain rough rice treated with malathion (14 ppm) or chlorpyrifos methyl (Reldan) (6 ppm or 12 ppm) was sampled after 1,6, and 12 wk. Samples from each treatment were processed raw or were parboiled with fresh steeping water, once-used, and twice-used steeping water. Three replicates of rough rice and of each milling fraction were preserved, and three of milled rice were cooked. Chemical residues were measured on rough rice, hulls, brown rice, bran, milled rice, and cooked rice. Parboiling reduced residues on rough rice and hulls but tended to increase residues in the other fractions. Residues of Reldan in bran were substantially increased by parboiling. Doubling the amount of Reldan applied to rough rice approximately doubled the residues found in the milling fractions. Small amounts of the protectants survived all processing including cooking. Residues of malathion in cooked rice averaged about 0.016 ppm in nonparboiled and 0.013 ppm in parboiled rice. Residue of Reldan in cooked rice was commensurate with the amount applied to rough rice. When applied to rough rice at 6 ppm, residues of Reldan in cooked rice averaged 0.05 ppm in nonparboiled rice and 0l.065 ppm in parboiled rice. When applied to rough rice at 12 ppm, residues in cooked rice averaged .053 ppm in nonparboiled rice and 0.15 ppm in parboiled rice. Legal tolerances were not exceeded in any milling fraction. Reuse of the steeping water had little or no effect on residues.

[The control of Aedes (Stegomyia) and related species involved in transmission of human arbovirus infections in tropical Africa (author's transl)]. / Le côntrole des Aedes (Stegomyia) et espèces voisines vecteurs d'arboviroses humaines, en Afrique tropicale.

In Africa, many Aedes mosquitos are involved in yellow fever and dengue transmission. Their control can be carried out either in a "prophylactic" way, when no disease occurs, or in a "curative" one, when virus is detected in the human community. In the first event, control is confounded with sanitation measures; in the second event, insecticidal control is needed against both larvae and adults. Larvae populations are destroyed by means of insecticidal deposits in the breeding-sites. Control of adults is achieved by thermal fogs or U.L.V. applications of organophosphorous compounds dispensed from ground or aerial generators. The insecticide susceptibility level of every Aedes populations involved in arbovirus transmission must be periodically determined with all the insecticides available.