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At least 37 records · Page 2Linked to original sources

Cancer mortality among local authority pest control officers in England and Wales.

OBJECTIVE: To examine cancer mortality by tumour site among local authority pest control officers. METHODS: Prospective mortality study, and follow up to the end of 1994, of 1485 male pest control officers aged between 17 and 69 and employed in 296 local authorities in England and Wales for at least six months between January 1980 and April 1984. Observed numbers of deaths were compared with those expected on the basis of the rates for relevant calendar year, cause, sex, and age specific groups for England and Wales. RESULTS: 200 deaths occurred during the follow up period of which 65 were certified as due to malignant neoplasms. No tumour type showed significantly more deaths than expected. Total all cause, lung cancer, and respiratory disease mortality were significantly lower than expected. CONCLUSIONS: 15 year follow up of a group of men handling a wide range of pesticides did not show any significant risk of cancer. This may be partially explained by the healthy worker effect and also the limited power of the study to detect significant increases in the less common tumours. Further long term follow up of this cohort will continue. Chemical control of pests that can cause human disease and can contaminate food and water has been, and will continue to be, a major public health measure. It is important to ensure that the health of those applying pesticides is not at excess risk. Negative results are important.

Adolescent↗

Host-host-pathogen models and microbial pest control: the effect of host self regulation.

A model has been investigated of the dynamics of the interaction between two hosts that are both attacked by a common pathogen with free-living infective stages, where the hosts are also subject to self-regulation. If either host interacted with the pathogen alone, two types of dynamics would be possible: an uninfected state where the host settles at its carrying capacity, and an infected state where the host settles at, or cycles around, a density lower than the carrying capacity. The three possible combination of two hosts have been investigated: uninfected-uninfected (both hosts uninfected if alone with the pathogen), infected-uninfected and infected-infected. A range of dynamics is generated, depending on parameter values, including infected co-existence of the two hosts (arrived at by a variety of routes), uninfected co-existence of the two hosts, exclusion of one host by the other which remains in an infected state, and a number of outcomes contingent on the initial densities in the system. Free-living infective stages make uninfected co-existence more likely and introduce additional contingency into the dynamics. The implications for microbial pest control are into the dynamics. The implications for microbial pest control are markedly different from those derived from related models without host self-regulation. There appears to be little chance of a non-target host undermining pest control, relatively little chance of the non-target enhancing pest control and a small but non-negligible threat to non-targets when parameter values are appropriate. The application of the results is commended but great caution is urged.

Animals↗

[Increased mortality from esophageal cancer, stomach cancer and skin melanoma in pesticide-exposed pest control operators in the DDR].

A retrospective mortality study on male pest control workers of the German Democratic Republic (GDR) was undertaken to evaluate the association of exposure to pesticides and development of malignant tumors. The cohort encompassed 1,214 male subjects with at least 5 years pest control work between 1945 and 1980. Informations on causes of death and cancer cases were obtained from death certificates and the cancer registry form. As control cohort for the standardized mortality ratios (SMR) served the general male population of the GDR. The SMR of 133 for the category of malignant tumors in the pesticide exposed cohort was significantly elevated. Among the other causes of death categories the SMR was less than 100. The tumor excess was statistically significant for the following tumor sites: esophagus, SMR = 430 (4 observed vs. 0.9 expected); stomach, SMR = 180 (14 observed vs. 7.8 expected) and skin melanoma, SMR = 588 (2 observed vs. 0.3 expected). Mortality from stomach cancer showed a linear rising trend by number of years licensed (less than 10 years, SMR = 118; 10-19 = 160; greater than 19 years, SMR = 260). The data suggest an etiological link between the pesticide exposure and increased mortality of esophagus cancer, stomach cancer and skin melanoma.

Esophageal Neoplasms↗

Pest control by the release of insects carrying a female-killing allele on multiple loci.

With recent advances in genetics, many new strategies for pest control have become feasible. This is the second article in which we model new techniques for pest control based on the mass release of genetically modified insects. In this article we model the release of insects carrying a dominant and redundant female killing or sterilizing (FK) allele on multiple genetic loci. If such insects are released into a target population, the FK allele can become widely spread in the population through the males while reducing the population each generation by killing females. We allow the number of loci used to vary from 1 to 20. We also allow the FK allele to carry a fitness cost in males due to the gene insertions. Using a model, we explore the effectiveness and optimal strategies for such releases. In the most ideal circumstances (no density-dependence and released insects equal in fitness to wild ones), FK releases are several orders of magnitude more effective than equal sized sterile male releases. For example, a single release of 19 FK-bearing males for every two wild males, with the released males carrying the FK allele on 10 loci, reduces the target population to 0.002% of no-release size. An equal sized sterile release reduces the target population to 5% of no-release size. We also show how the effectiveness of the technique decreases as the fitness cost of the FK alleles in males increases. For example, the above mentioned release reduces the target population to 0.7% of no-release size if each FK allele carries a fitness cost in males of 5%. Adding a simple model for density-dependence and assuming that each of the released males carries the FK allele on six loci, we show that the release size necessary to reduce the target population to 1/100 of no-release size in 10 generations of releases varies from 0.44:1 to 4:1 (depending on parameter values). We also calculate the optimal number of loci on which to put the FK allele under various circumstances.

Alleles↗

Controlled release effect of insecticide microcapsules and their results in common household insect pest control.

Since 1978 we have prepared microencapsulated insecticides by complex coacervation and interfacial polymerization for household insect pest control, fenthion being the main core element. A series of tests have been conducted against mosquitoes (Culex pipiens quinquefasciatus), cockroaches (Periplaneta americana) and bedbugs (Cimex lectularius), and the results indicate that microencapsulation can prolong persistent effects by 2-12 times, enhance safety and subdue offensive odour. Furthermore, the production cost is comparatively low.

Animals↗

[Retrospective cohort study of the cancer incidence in pesticide-exposed male pest control workers].

A cohort of 1,214 pest control workers employed during 1945-1980 for at least 5 yr was investigated with regard to cancer mortality. Standardized Mortality Ratio (SMR) was significantly elevated for all malignant neoplasms (SMR = 133; 65 observed vs. 48.5 expected). Significantly elevated SMRs were also found for the following tumor sites: esophagus, SMR = 430 (4 observed vs. 0.9 expected); stomach, SMR = 180 (14 observed vs. 7.8 expected) and melanoma, SMR = 588 (2 observed vs. 0.3 expected). Mortality from stomach cancer showed a rising trend by number of years licensed (less than 10 years, SMR = 118; 10-19 years, SMR = 160; greater than 19 years, SMR = 260). The findings help clarify the role of occupational pesticide exposure as a risk factor for cancer.

Adenocarcinoma↗

[Sensitization and allergic pathology in a group of workers employed in insect breeding for biological pest control].

On the basis of the results of a previous study and immuno-allergological tests, a group of workers employed in breeding insects for biological pest control were studied to ascertain whether any new sensitizations to arthropods recently included in the work cycle occurred and whether any new allergic diseases were observed. The results confirmed a high sensitization to Ephestia kuehniella and to Orius, the latter probably due to contamination; sensitization to Tetranicus urticae and to Planococcus citri were observed, although to a lesser degree. It is concluded that the insects used in biological pest control are highly allergogenic and that the protective devices used up to the present were ineffective; the authors therefore recommend the use of closed or semi-closed cycles along with local ventilation equipment.

Adult↗

Possibilities of using insectistatics and pheromones in pest control.

Agents that can decimate insect populations by suppressing growth and reproduction rather than by causing rapid mortality are called insectistatics. Their activity includes interruption of cuticle formation, induction of hormonal imbalance by extrinsic juvenoids or ecdysoids, developmental disturbances due to nutrient antagonists, symbioticides, or accelerators of metabolism. Disruption of mating may be accomplished by pheromone trapping and disorientation or by prevention of sex attraction. The possible contribution of such biotechnical procedures to the control of storage pests is discussed.

Animals↗

A behavioral evaluation of pest control workers with short-term, low-level exposure to the organophosphate diazinon.

Neurobehavioral effects of short-term, low-level exposure to diazinon were investigated among 99 pest control workers tested before and after their work shift with a computer-assisted neurobehavioral test battery. Each subject completed a brief neurological screening examination, a symptom questionnaire, and tests of concentration, eye-hand coordination, pattern recognition, visual memory, and finger tapping. The diazinon metabolite diethylthiophosphate (DETP) was measured in pre- and post-shift urine samples collected from 46 diazinon applicators applying granulated diazinon onto residential properties with lawn spreaders, and 56 non-applicators. Post-shift median DETP for applicators and non-applicators was 24 and 3 ppb, respectively. Full shift, whole body exposure to diazinon was quantitated for 19 subjects using personal air monitoring and passive badges. Median diazinon exposure for applicators and non-applicators was 2.1 and 0.03 mg, respectively. Mean duration of pesticide application was 39 days (SD = 12 days) before testing. No adverse DETP-related changes in pre- or post-shift neurobehavioral function were found with multiple linear regression models after adjusting for age, sex, education, and ethanol intake, although Symbol-Digit pairing speed was slower among the applicators as a group. The prevalence of 18 symptoms possibly related to diazinon exposure was not elevated among applicators. The study failed to demonstrate diverse behavioral effects of short-term, low-level diazinon exposure in a pest control program which emphasized personal protective equipment and direct supervision.

Adult↗

[Textile pest control in textile stores with a combination preparation of methoxycholor and chlorpyrifos [0,0-diethyl-(3,5,6-trichloro-2-pyridyl)-monothiophosphate]].

The effect on man of a mixture of methoxyclorine and 0,0-diethyl-(o8k8l-trichloro-2-pyridyl)-monothiophosphate (chlorpyrifos) used for textile pest control in poorly ventilated textile storages were examined under realistic test conditions. The chronical exposure of the test persons to chlorpyrifos, although originally thought to be of a negligible order, surprisingly resulted in an approximately 40% inhibition of the serum chlinesterase (ChE) without any significant spontaneous recovery of the ChE activity in three out of four test subjects during the test period. On the contrary, the activity of the acetylcholinesterase of the erythrocytes (AChE), after a temporary insignificant decrease, was found to be considerable increased for the duration of the test. As a result of these examinations it is recommended not to use insecticides containing alkylphosphates for textile pest control in poorly ventilated reeom if an exposure of man during the desorption phase cannot be excluded.

Acetylcholinesterase↗

Biological monitoring of pyrethroid metabolites in urine of pest control operators.

Due to their low mammalian toxicity but high insectical activity, pyrethroids are increasingly used for pest control. The objective of the present study was the development of a biological monitoring program to determine exposure to pyrethroids. A diastereoselective detection of the major pyrethroid metabolites cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid, cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylic acid, 3-phenoxybenzoic acid and fluorophenoxybenzoic acid by capillary gas chromatography in combination with mass selective detection was applied. The limits of determination ranged between 0.5 and 1 microgram/l urine, depending on the metabolite concerned. It was demonstrated that pyrethroid metabolites were detectable in urine for a period of elimination up to 3.5 days after exposure to cyfluthrin. Fluorophenoxybenzoic acid was shown to be a suitable biomarker for exposure to cyfluthrin. The presented method was adequate for monitoring pyrethroids in occupationally exposed subjects.

Adult↗

[Four-year follow-up of a group of workers with allergic sensitization employed in breeding of insects for biological pest control].

In two previous papers we reported allergic diseases in workers employed in breeding insects for biological pest control. It was found that Ephestia kuehniella, Orius laevigatus and other insects caused allergic rhinoconjunctivitis and asthma. The aim of this new study was to assess the relationship between the implementation of the recommended preventive measures and the decrease in sensitization in exposed workers. We performed a four-year follow-up of exposed workers, using the prick test and RAST with specific allergens and pulmonary function test at the end of the work shift. The results showed a decrease in skin test sensitization for Orius and Ephestia, a decrease in allergic diseases in the previously studied workers, and no symptoms in recently employed workers. These results confirm the validity of the recommended preventive measures: semi-closed cycles, gloves, protective masks, overalls and sunglasses.

Adult↗

Development of amphiphylic mimics of insect neuropeptides for pest control.

Insect neuropeptides regulate virtually all aspects of insect life and are excellent candidates for development of new methods for pest control. However, they do not penetrate insect cuticle and are degraded by enzymes both in the digestive system and hemolymph. We have designed mimics of model neuropeptides by attachment of various lipidic moieties to the amino terminus of the bioactive core of the neuropeptides. These mimics have amphiphylic characteristics that allowed them to penetrate the hydrophobic insect cuticle. The mimics also induced prolonged physiological responses (up to 20 hours) and were resistant to peptidase attack. This knowledge has been used to develop a novel, species-specific approach to insect control.

Animals↗

Estimating economic thresholds for pest control: an alternative procedure.

An alternative methodology to determine profit maximizing economic thresholds is developed and illustrated. An optimization problem based on the main biological and economic relations involved in determining a profit maximizing economic threshold is first advanced. From it, a more manageable model of 2 nonsimultaneous reduced-from equations is derived, which represents a simpler but conceptually and statistically sound alternative. The model recognizes that yields and pest control costs are a function of the economic threshold used. Higher (less strict) economic thresholds can result in lower yields and, therefore, a lower gross income from the sale of the product, but could also be less costly to maintain. The highest possible profits will be obtained by using the economic threshold that results in a maximum difference between gross income and pest control cost functions.

Animals↗

Relationship between chlordane and its metabolites in blood of pest control operators and spraying conditions.

Chlordane has been widely used to protect soil and house foundations against termite infestation. Pest control operators (PCOs) are occupationally exposed to chlordane. The relationship between chlordane and its metabolites in blood of PCOs and spraying conditions were investigated. Chlordane and its metabolites were detected in the blood of some chlordane-exposed PCOs, but not in that of the controls. Trans-nonachlor and the metabolites oxychlordane and heptachlor epoxide were detected in the blood of PCOs. Total concentration of chlordane and its metabolites in blood (trans-nonachlor + oxychlordane + heptachlor epoxide) was less than 5.6 ppb (mean: 0.89 ppb). The concentration of chlordane and its metabolites in blood of chlordane-exposed PCOs was significantly correlated with the number of spraying days and the amount of chlordane sprayed, particularly with a large correlation coefficient (r = 0.81, P less than 0.001) with the spraying days in the three months prior to the medical examination. The concentration of chlordane and its metabolites in blood is considered to be a useful indicator of biological monitoring for chlordane exposed workers (PCOs).

Adult↗