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PubMed2006

Feasibility of LC/TOFMS and elemental database searching as a spectral library for pesticides in food.

Traditionally, the screening of unknown pesticides in food has been accomplished by GC/MS methods using conventional library-searching routines. However, many of the new polar and thermally labile pesticides are more readily and easily analysed by LC/MS methods and no searchable libraries currently exist (with the exception of some user libraries, which are limited). Therefore, there is a need for LC/MS libraries that can detect pesticides and their degradation products. This paper reports an identification scheme using a combination of LC/MS time-of-flight (accurate mass) and an Access database of 350 pesticides that are amenable to positive ion electrospray. The approach differs from conventional library searching of fragment ions. The concept consists of three parts: (1) initial screening of possible pesticides in actual market-place fruit extracts (apple and orange) using accurate mass and generating an accurate mass via an automatic ion-extraction routine, (2) searching the Access database manually for screening identification of a pesticide, and (3) identification of the suspected compound by accurate mass of at least one fragment ion and comparison of retention time with an actual standard. Imazalil and iprodione were identified in apples and thiabendazole in oranges using this database approach.

Aminoimidazole Carboxamide↗
PubMed2000

Degradation of atrazine, metolachlor, and pendimethalin in pesticide-contaminated soils: effects of aged residues on soil respiration and plant survival.

This study was conducted to determine the effects of pesticide mixtures on degradation patterns of parent compounds as well as effects on soil microbial respiration. Bioavailability of residues to sensitive plant species was also determined. Soil for this study was obtained from a pesticide-contaminated area within an agrochemical dealer site. Degradation patterns were not affected by the presence or absence of other herbicides in this study. Atrazine concentrations were significantly lower at 21 through 160 days aging time compared to day 0 concentrations. Metolachlor and pendimethalin concentrations were not significantly different over time and remained high throughout the study. Microbial respiration was suppressed in treated soils from day 21 to day 160. Soybean and canola were the most successful plant species in the germination and survival tests. Generally, with increased aging of pesticides in soil, germination time decreased. Survival time of plants increased over time for some treatments indicating possible decreased bioavailability of pesticide residues. In some cases, survival time decreased at the longer 160-day aging period, possibly indicating a change in bioavailability, perhaps as the result of formation of more bioavailable and phytotoxic metabolites. No interactive effects were noted for mixtures of pesticides compared to individually applied pesticides in terms of degradation of the parent compound or on seed germination, plant survival, or microbial respiration.

Acetamides↗
PubMed2006

Application of automated mass spectrometry deconvolution and identification software for pesticide analysis in surface waters.

A new approach to surface water analysis has been investigated in order to enhance the detection of different organic contaminants in Nathan Creek, British Columbia. Water samples from Nathan Creek were prepared by liquid/liquid extraction using dichloromethane (DCM) as an extraction solvent and analyzed by gas chromatography mass spectrometry method in scan mode (GC-MS scan). To increase sensitivity for pesticides detection, acquired scan data were further analyzed by Automated Mass Spectrometry Deconvolution and Identification Software (AMDIS) incorporated into the Agilent Deconvolution Reporting Software (DRS), which also includes mass spectral libraries for 567 pesticides. Extracts were reanalyzed by gas chromatography mass spectrometry single ion monitoring (GC-MS-SIM) to confirm and quantitate detected pesticides. Pesticides: atrazine, dimethoate, diazinone, metalaxyl, myclobutanil, napropamide, oxadiazon, propazine and simazine were detected at three sampling sites on the mainstream of the Nathan Creek. Results of the study are further discussed in terms of detectivity and identification level for each pesticide found. The proposed approach of monitoring pesticides in surface waters enables their detection and identification at trace levels.

Automation↗
PubMed2006

Adverse health effects of children's exposure to pesticides: what do we really know and what can be done about it.

UNLABELLED: Children may be exposed to pesticides in several ways, such as by transplacental transfer during foetal life, by intake of contaminated breast milk and other nutrients, or by contact with contaminated subjects and areas in the environment such as pets treated with insecticides, house dust, carpets and chemically treated lawns and gardens. Exposure early in life, and particularly during periods of rapid development, such as during foetal life and infancy, may have severe effects on child health and development by elevating the risk of congenital malformations, cancer, malabsorption, immunological dysfunction, endocrine disease, and neurobehavioural deficiencies. As pesticides can also interfere with parental reproductive health, exposure of parents may have consequences for the offspring leading to reduced chance of male birth and increased risk of childhood cancer. CONCLUSIONS: Current knowledge about tolerable levels and consequences of toxic exposure to pesticides during human development is rather scarce. Owing to the high risk of exposure to pesticides, particularly in less developed countries, further elucidation by well-controlled epidemiological studies in this field it is urgently needed. The Policy Interpretation Network on Children's Health and Environment (PINCHE), which is financed by the EU DG research has suggested actions against pesticide exposure. They have been presented and discussed in this paper. Several suggestions of PINCHE concerning action needed regarding pesticides were presented in the paper.

Child↗
PubMed1999

Degradation of pesticides by actinomycetes.

Actinomycetes have considerable potential for the biotransformation and biodegradation of pesticides. Members of this group of Gram-positive bacteria have been found to degrade pesticides with widely different chemical structures, including organochlorines, s-triazines, triazinones, carbamates, organophosphates, organophosphonates, acetanilides, and sulfonylureas. A limited number of these xenobiotic pesticides can be mineralized by single isolates, but often consortia of bacteria are required for complete degradation. Cometabolism of pesticides is frequently observed within this group of bacteria. When compared with pesticide degradation by Gram-negative bacteria, much less information about molecular mechanisms involved in biotransformations of pesticides by actinomycetes is available. Progress in this area has been seriously hampered by a lack of suitable molecular genetic tools for most representatives of this major group of soil bacteria. Overcoming this constraint would enable a better exploitation of the biodegradation and biotransformation abilities of actinomycetes for applications such as bioremediation and construction of transgenic herbicide-resistant crops.

Actinomyces↗
PubMed1998

Pesticide exposures and fetal death: a review of the epidemiologic literature.

Despite considerable concern regarding the effects on reproductive outcome of exposures to pesticides, convincing evidence for the developmental toxicity of occupational and environmental pesticide exposure in humans is lacking. In this comprehensive review of the English language epidemiologic literature, we summarize studies that have examined potential associations between fetal deaths (both spontaneous abortions and stillbirths) and specific pesticides, as well as maternal and paternal employment in occupations with potential for exposure. While many of the epidemiologic studies to date suffer from methodologic problems, the data are suggestive of increased risks of fetal deaths associated with pesticides in general and maternal employment in the agricultural industry. There is a clear need for epidemiologic research that focuses on specific pesticide products or chemical families, with improved exposure assessment. The potential role of solvents in developmental toxicity associated with pesticide use by both males and females should also be considered.

Agricultural Workers' Diseases↗
PubMedDate not supplied

Importance of respiratory exposure to pesticides among agricultural populations.

In the majority of cases, respiratory exposure accounts for a small fraction of total body exposure to pesticides; however, higher volatility pesticides pose a greater risk for exposure, particularly in enclosed spaces and near application sites. In 2000, nearly 22 million pounds of active ingredients designated as toxic air contaminants (TACs) were applied as pesticides in California (combined agricultural and reportable non-agricultural uses; California Department of Pesticide Regulation, 2001a, Summary of Pesticide Use Report Data, 2000, Sacramento, CA: author). Agricultural workers and agricultural community residents are at particular risk for exposure to these compounds. The TAC program in California, and more recently the federal Clean Air Act amendments, have begun to address the exposures of these groups and have promulgated exposure guidelines that are, in general, much more stringent than the Occupational Safety and Health Administration (OSHA) and American Conference of Governmental Industrial Hygienists (ACGIH) worker exposure guidelines. Choosing lower volatility pesticides, lower concentrations of active ingredients, and handling equipment designed to minimize exposure can often reduce worker respiratory exposures significantly. The use of personal protective equipment, which would be facilitated by the development of more ergonomic alternatives, is important in these higher respiratory exposure situations. Finally, in the case of community residents, measures taken to protect workers often translate to lower ambient air concentrations, but further study and development of buffer zones and application controls in a given area are necessary to assure community protection.

Agricultural Workers' Diseases↗
PubMedDate not supplied

Pesticide impacts on communities and schools.

Early efforts directed toward the development of pesticide regulations addressed serious acute illnesses associated with pesticide mixing, loading, and application. As those pesticide exposures and illnesses came under control through official regulatory action, attention has turned toward problems associated with the impacts of pesticides on communities and schools. By contrast to the early successes in bringing major acute poisoning under control, the problems of pesticide impacts on communities and schools have been especially difficult to resolve through the regulatory process. This article discusses the dynamics of the new and emerging impacts of pesticides on communities and schools, with an emphasis upon California experiences.

California↗
PubMedDate not supplied

Increased risk of lung cancer in pesticide-exposed male agricultural workers.

The cancer morbidity in a large group of male German agricultural workers exposed to pesticides was investigated through a retrospective cohort study. A total of 169 malignant tumors were diagnosed in 1658 men who began to work with pesticides between 1948 and 1972, and who continued this type of activity for at least 5 yr. The SMR (standardized mortality ratio) of 2.0 for lung cancer morbidity (mortality) in these pesticide-exposed subjects was significantly higher than that for the general male population of the German Democratic Republic. A positive correlation between the duration of employment and the mortality due to lung cancer (mainly undifferentiated and small-cell carcinomas) suggested a dose-effect relation. The smoking habits of the exposed men did not differ from those of the general male population of the German Democratic Republic. Because the subjects had been exposed to many different substances, the study does not permit any conclusions to be drawn in respect to the carcinogenicity of individual pesticides. The increased mortality due to lung cancer is presumably the result of an additive effect of different pesticide ingredients or of by-products whose carcinogenic effect has been definitely or tentatively established through experimental or epidemiologic studies (e.g. arsenic, asbestos, chlorinated dibenzodioxins, DDT). The results of the present investigation emphasize the need for effective measures to protect workers during occupational contact with pesticides.

Adult↗
PubMed1992

Permeation resistance of glove materials to agricultural pesticides.

The toxicities of many agricultural pesticides require that hand protection be used by persons who mix, load, and apply these products, as specified on the label and material safety data sheet. Selection of gloves for formulations that contain organic solvents is particularly problematic because a solvent that permeates the glove can carry with it the active ingredient of the pesticide formulation. With a test method that measures the simultaneous permeation of the carrier solvent(s) and active ingredient(s), in particular those active ingredients that have low solubility in water and low volatility, over 100 permeation tests (in triplicate) with approximately 20 pesticide formulations were conducted with 13 different glove materials. These results are summarized and generalizations are presented within the perspective of the large base of permeation data for neat chemicals and another large permeation study with pesticides. Key among the findings is that the carrier solvent generally permeates first and at a much higher rate than the active ingredient. Furthermore, the permeation behavior of formulations containing solvents generally mirrored that of neat carrier solvents alone. Thus, insight into the selection of the most appropriate glove material for a given pesticide formulation can be gained from permeation data for neat chemicals. For the types of solvents that may be present in pesticide formulations, preferred materials include nitrile rubber, butyl rubber, and plastic film laminates. Natural rubber and polyvinyl chloride materials generally are not recommended.

Agrochemicals↗
PubMed2002

Inhibition of Paracoccidioides brasiliensis by pesticides: is this a partial explanation for the difficulty in isolating this fungus from the soil?

The aim of this study was to evaluate the effect of ten pesticides on Paracoccidioides brasiliensis, and thereby to investigate the possible association between these data and the difficulty in isolating P. brasiliensis from agricultural soil. Six fungicides (Alto 100, Benlate, Captan, Dithane, Plantacol, Rovral), two herbicides (Pivot, Roundup) and two insecticides (Azodrin and Curacron) were evaluated. Five P. brasiliensis isolates from the environment (labelled group 'N,' for 'nature') and five isolates from patients (group 'P'), were grown on Sabouraud's dextrose agar, at 35 degrees C, with ten different concentrations of each pesticide. The dose of pesticide that causes 50% growth inhibition (ED50) was calculated for each isolate. All pesticides assayed inhibited P. brasiliensis in a dose-dependent manner, and great variability among ED50 values was observed in isolates from both groups. No statistically significant difference was observed between averages of ED50 from groups N and P, except with Alto 100. The inhibitory effect of pesticides on P. brasiliensis suggests that they can interfere with attempts to isolate P. brasiliensis from soil, where tonnes of pesticides are applied over large areas planted with various crops.

Dose-Response Relationship, Drug↗
PubMed2004

In vitro percutaneous penetration of five pesticides--effects of molecular weight and solubility characteristics.

This study examined the in vitro percutaneous penetration of five pesticides covering a wide range of solubilities and different molecular weights, which allowed discussion of penetration of single pesticides as well as a comparison between penetration characteristics of different pesticides. The five pesticides were the fungicides methiocarb, pirimicarb and prochloraz; the growth retardant paclobutrazol; and the insecticide dimethoate. An experimental model with static diffusion cells mounted with human breast skin was used, and pesticide concentrations were quantified by high-performance liquid chromatography. Molecular weight as well as solubility affected dermal penetration and skin deposition. Thus, we conclude that for the passage of our test substances from the donor phase, through the skin, into the receptor, a too high as well as a too low lipophilicity may limit the rate and degree of skin penetration. Furthermore, the importance of the skin as a potential reservoir for systemic exposure after exposure has ended was demonstrated. Especially in relation to short-term occupational exposures, an exposure assessment based on penetrated pesticide at the end of a work shift may underestimate the exposure.

Breast↗
PubMed2005

Assessment of pesticide exposure in the agricultural population of Costa Rica.

We describe a model for the retrospective assessment of parental exposure to 26 pesticides, selected by toxicity-based prioritization, in a population-based case-control study of childhood leukaemia in Costa Rica (301 cases, 582 controls). The model was applied to a subset of 227 parents who had been employed or self-employed in agriculture or livestock breeding. It combines external data on pesticide use for 14 crops, 21 calendar years and 14 regions, and individual interview data on determinants (task and technology, personal protective equipment, field reentry, storing of pesticides, personal hygiene) of exposure. Recall was enhanced by use of checklists of pesticides in the interview. An external database provided information on the application rate (proxy for intensity of potential exposure) for each pesticide. The calendar time was individually converted to five time windows (year before conception, first, second and third trimester, and first year of the child). Time-windowed individual data on determinants of exposure and their expert-based general weights and their category-specific hazard values jointly provided an individual determinant score. This score was multiplied by the application rate to obtain an individual index of exposure intensity during application. Finally, average exposure intensity during entire time windows was estimated by incorporating in the model the individual time fraction of exposure during application. Estimates of exposure intensities were proxies assumed to be proportional to dermal exposure intensity, which represents the major pathway of occupational exposure to pesticides. A simulated sensitivity analysis resulted in a correlation coefficient of 0.91 between two sets of 10 000 values of individual exposure indices, based on two different but realistic sets expert-assigned weights. Lack of measurement data on concurrent exposures in comparable circumstances precluded direct validation of the model.

Adult↗
PubMed2000

Clean-up of a pesticide-lanolin mixture by gel permeation chromatography.

In this study, the efficiency of a clean-up method by gel permeation chromatography (GPC) for the separation of pesticides from lanolin is analyzed. The pesticides analyzed belong to two different families, organophosphorous and synthetic pyrethroids. Lanolin, a standard mixture of the pesticides, and a lanolin-pesticides mixture are injected in a GPC column. The recoveries and elution times from the GPC column of lanolin (by a gravimetric method) and pesticides (by gas chromatography-electron capture detector) are determined. From this column, a good separation of the lanolin-pesticides mixture is observed.

Chromatography, Gas↗
PubMed1996

Cancer incidence among Icelandic pesticide users.

BACKGROUND: This study was done to examine the cancer risk among pesticide users in Iceland. METHODS: We have followed a cohort of 2449 licensed pesticide users, students from a horticultural college, members of a pension fund for market gardeners, horticulturists and vegetable farmers up until the end of 1993 in the Icelandic Cancer Registry of cancer incidence. The observed number of cancers was compared with expected values calculated on the basis of cancer incidence for males and females in Iceland. RESULTS: The standardized incidence ratio (SIR) for all cancer sites was 0.80. Among females the increased incidence for cancer of lymphatic and haematopoietic tissue was significant (SIR = 5.56, 95% confidence interval (CI) 1.12-16.23). The incidence of rectal cancer was three times that expected (SIR = 2.94, 95% CI: 1.07-6.40), and this cancer was even more predominant among the licensed pesticides users (SIR = 4.63, 95% CI: 1.49-10.80). All cancers of the rectum were adenocarcinoma, however, one was adenocarcinoma in villous adenoma and one adenocarcinoma in tubulo-villous adenoma. CONCLUSION: The results provide some support for the suggestion that pesticide exposure may lead to cancer of the lymphatic and haematopoietic tissue in females. We suggest that some of the pesticides to which the licensed pesticide users were exposed may lead to rectal cancer.

Aged↗
PubMed2002

Print media coverage of risk-risk tradeoffs associated with West Nile encephalitis and pesticide spraying.

When mosquito-borne West Nile virus emerged in the United States in 1999 and triggered pesticide spraying, society was faced with a controversy over an important risk-risk tradeoff-the risks of pesticide exposure versus those of West Nile encephalitis. Effective public communication about risk-risk tradeoffs is important because it can assist individuals and society in investing resources optimally. This study examined how effectively major North American print media in the year 2000 provided information on this risk-risk tradeoff. My colleagues and I found that the print media were generally ineffective in providing precise information about pesticide risks and in comparing risks of pesticide exposure with those of West Nile encephalitis. The media were also ineffective in mentioning the efficacy of pesticide spraying or comparing the economic costs of pesticide spraying with those of West Nile encephalitis. We suggest that greater effort in collecting and reporting precise risk information, fostering more active relationships between journalists and scientists/public health professionals, and recognizing biases resulting from preconceptions can help improve reporting by the print media and public health agencies on risk-risk tradeoffs associated with emerging insect-borne infectious diseases. These efforts could help improve public health by improving decision making related to the control of insect-borne diseases.

Animals↗
PubMed2006

Neurotoxicological interactions of a five-pesticide mixture in preweanling rats.

The estimation of risk following exposure to mixtures is an important feature of pesticide risk assessment. Also of concern is the potential for increased sensitivity of the young to pesticide toxicity. We have conducted interaction studies using a mixture of five organophosphorus (OP) pesticides (chlorpyrifos, diazinon, dimethoate, acephate, and malathion) in both adult (published previously) and preweanling rats using a fixed-ratio ray design. In the present study, cholinesterase inhibition and behavioral changes (motor activity, gait, and tail-pinch response) were measured in 17-day-old Long-Evans male rats following acute exposure to the OPs. The ratio of pesticides in the mixture reflected the relative dietary exposure estimates projected by the U.S. Environmental Protection Agency Dietary Exposure Evaluation Model. Dose-response data were collected for each OP alone, which were used (alone or in conjunction with the mixture data) to build an additivity model to predict the effects of the pesticide mixture along a ray of increasing total doses, using the same fixed ratio of components. The mixture data (full ray) were similarly modeled and statistically compared to the additivity model along the ray. Since malathion has been shown to produce synergistic interactions with certain OPs, it was of interest to evaluate the influence of malathion in this study. A second pesticide mixture, without malathion (reduced ray), was tested using the same dose levels of the remaining four OPs. Analysis of the full ray revealed significant greater-than-additive responses for all endpoints. The magnitude of this shift ranged from two- to threefold for estimates of the ED(20) and ED(50). The deviation from additivity was also detected in the reduced ray for all but two endpoints (motor activity and tail-pinch response); however, for all endpoints, the reduced ray was significantly different from the full ray. Thus, greater-than-additive responses were detected in preweanling rats with this OP mixture, and this effect can only partially be attributed to the malathion in the mixture.

Animals↗
PubMed2001

Residential pesticide exposure and neuroblastoma.

Neuroblastoma is the most common neoplasm in children under 1 year of age. We examined the relation between residential exposure to pesticides and neuroblastoma, using data from a case-control study of risk factors for neuroblastoma. Incident cases of neuroblastoma (N = 538) were identified through the Pediatric Oncology Group and the Children's Cancer Group. One age-matched control was identified for each case by random digit dialing. Telephone interviews with each parent collected information on residential exposure to pesticides. Pesticide use in both the home and garden were modestly associated with neuroblastoma [odds ratio (OR) = 1.6 (95% confidence interval [95% CI] = 1.0-2.3, and OR = 1.7 (95% CI = 0.9-2.1), respectively]. Compared with infants [OR = 1.0 (95% CI = 0.6-2.0)], stronger associations were found for garden pesticides in children diagnosed after 1 year of age [OR = 2.2 (95% CI = 1.3-3.6)], which suggests that pesticides may act through a mechanism more common for neuroblastomas in older children. There was no evidence of differential pesticide effects in subgroups of neuroblastoma defined by MYCN oncogene amplification or tumor stage.

Canada↗