Hazards associated with aerial spraying of organophosphate insecticides in Israel.

Aerial application of organophosphates can result in exposure to drift and leaf residues for pilots, ground crews, field workers, and residents near sprayed fields. Exposure can be by either the airborne or dermal route, and can produce illness (headaches, fatigue, diarrhea, cramps, respiratory problems) even with low-grade depressions in cholinesterase. Alkyl phosphate metabolites have been shown to be "gold standard" measures of such exposures. Experience in Israel indicates that reduction of health hazards from exposure to drift and leaf residues may be attained by the use of a comprehensive "mix" of preventive measures. These measures include, first and foremost, reduction in total amount of organophosphates used, followed by substitution of less for more toxic organophosphates, reduction in length of spray season, banning the use of flaggers, and greater reliance on tractor spraying. Cotton yield per hectare cultivated has increased despite a reduction in use of pesticides of all kinds and organophosphates in particular. Enclosure and air-conditioning (to prevent heat stress) of cockpits, protective clothing, training and licensing of pilots have been implemented. Education and communication of information, in keeping with the right-to know principle on hazards and how they should be controlled and monitored, is a part of a comprehensive strategy. Aerial or ground spraying should produce no drift in adjacent residential communities. The criterion for achieving this goal is the absence of urine alkyl phosphate metabolites above the threshold of detection.     

Effects of aerial spraying of insecticides on nontarget macrobenthos in a mountain stream

The effects of aerial spraying of an insecticide were investigated in a mountain stream using a drift net. The concentration of fenitrothion (organophosphorus insecticide) in the river water increased to ca. 20 micrograms liter-1 3 hr after the spraying and decreased exponentially to half the peak value after 2 hr. A large number of aquatic insects were found drifting after the spraying. The total number of individuals which drifted in the daytime after spraying reached nine times the number found the previous night. The total number of species which drifted during the 24 hr following the spray increased to 43 from 17 on the previous day. Before the insecticide spraying, the drifting benthos were almost entirely made up of three species of Baetis (Ephemeroptera). However, many individuals of several species of Heptageniidae (Ephemeroptera), Apsilochorema sutshanum (Trichoptera), and Chironomidae (Diptera) drifted in addition to Baetis after the spray. A large number of young Baetis, which had not been seen in the natural night drift samples, were found drifting due to the insecticide. Natural night drift almost disappeared from the day following insecticide spraying. At the second insecticide spraying, conducted 20 days after the first, the number of individuals which drifted during the 24 hr following spraying decreased to only 0.85% of that in the first spraying although changes in insecticide concentration showed a similar pattern. Several species of Ephemeroptera were dominant among the fauna in the studied stream, and the causal relationships of this are discussed.     

The health consequences of aerial spraying illicit crops: The case of Colombia

This paper exploits variations in aerial spraying across time and space in Colombia and employs a panel of individual health records in order to study the causal effects of the aerial spraying of herbicides (glyphosate) on short-term health-related outcomes. Our results show that exposure to the herbicide used in aerial spraying campaigns increases the number of medical consultations related to dermatological and respiratory illnesses, as well as the number of miscarriages. These findings are robust to the inclusion of individual fixed effects, which compare the prevalence of these medical conditions for the same person under different levels of exposure to the herbicide used in the aerial spraying program over a period of 5 years. Also, our results are robust to controlling for the extent of illicit coca cultivation in the municipality of residence.     

The effects of aerial spraying with Bacillus thuringiensis Kurstaki on children with asthma

OBJECTIVE: To determine if aerially spraying a biological pesticide was associated with an increase in the symptoms or change in the Peak Expiratory Flow Rate of children with asthma. METHODS: A pre/post matched pairs cohort design was used. Children living in the spray zone were matched with children outside of the spray zone. Peak Expiratory Flow Rates, asthma symptoms and non-asthma symptoms were recorded in diaries. RESULTS: There were no differences in asthma symptom scores between subjects and controls, neither before nor after the spray; nor were there significant changes in Peak Expiratory Flow Rates for subjects after the spray period. CONCLUSIONS: No evidence of adverse effects from the use of the biological pesticide was found. We believe that this is the first paper to address the issue of whether or not aerial spraying with Btk has a harmful effect on children with asthma.     

Use of time to pregnancy to study environmental exposures

There is need in reproductive epidemiology for sensitive and convenient screening tools that can be used to study environmental and occupational exposures. The measurement of fecundability (the probability of pregnancy in each cycle) by ascertaining how long it takes couples to conceive, may be useful for this purpose. Theoretically, exposures that interfere with any of the biologic processes involved in achieving pregnancy could lower fecundability among exposed men or women. To evaluate problems with collecting data on time to pregnancy, telephone interviews were conducted with nearly 700 pregnant women who reported having planned their pregnancies. Power curves were developed based on the distribution of time to pregnancy in the interviewed population. These curves indicate that relatively small sample sizes are sufficient for investigating an exposure. For example, the authors estimate that to detect a given 50% drop in mean fecundability with 80% power would require data from 55 exposed and 55 unexposed women who are pregnant. Disadvantages of using time to pregnancy as a reproductive endpoint include susceptibility to selection bias and need for data on several potential confounding variables. The next step in evaluating time to pregnancy as a reproductive endpoint is to apply it in studies of environmental or occupational exposures.     

Asbestos in Colorado schools.

Forty-one public schools in Colorado were drawn at random and surveyed for asbestos-containing materials. After bulk samples of possible asbestos materials from the schools were collected and analyzed, the K2 asbestos screening test was used to eliminate samples that did not contain asbestos. Samples with positive results on the K2 test were analyzed by an outside laboratory by polarized light microscopy. The risk of potential exposure presented by these materials was then assessed for each site from which a sample was taken. Of 113 samples collected, results were negative for asbestos for only 10.6 percent by the K2 test. Of the 101 samples for which results were positive, 56 actually contained 1 or more forms of asbestos. Twelve of these 56 samples were from sprayed material; the remaining 44 were from other materials containing asbestos. Of the 41 schools sampled, 31 had asbestos materials in one of more locations. The potential exposure values for these materials ranged from very low to very high, but the majority had high-exposure potentials. Estimates based on the survey of the 41 schools indicated that 63 to 89 percent of the public schools in Colorado have asbestos materials that present potentially serious hazards, not only to the children, teachers, and staff, but also to members of the community who use the school buildings after regular school hours.     

Efficacy of aerial spraying of mosquito adulticide in reducing incidence of West Nile Virus, California, 2005

Epidemic transmission of West Nile virus (WNV) in Sacramento County, California, in 2005 prompted aerial application of pyrethrin, a mosquito adulticide, over a large urban area. Statistical analyses of geographic information system datasets indicated that adulticiding reduced the number of human WNV cases within 2 treated areas compared with the untreated area of the county. When we adjusted for maximum incubation period of the virus from infection to onset of symptoms, no new cases were reported in either of the treated areas after adulticiding; 18 new cases were reported in the untreated area of Sacramento County during this time. Results indicated that the odds of infection after spraying were approximately 6x higher in the untreated area than in treated areas, and that the treatments successfully disrupted the WNV transmission cycle. Our results provide direct evidence that aerial mosquito adulticiding is effective in reducing human illness and potential death from WNV infection.     

Use of a multistage model to predict time trends in smoking induced lung cancer.

STUDY OBJECTIVE--The aims were to use a mathematical model to predict the time course of smoking induced lung cancer, and to investigate to what extent the most recent increases in lung cancer mortality are due to cigarette smoking. DESIGN--A mathematical model was developed and solved by simulation to construct detailed smoking histories of the US white male population given available prevalence data by age and cohort. A multistage carcinogenesis model was used to predict the time course of smoking induced lung cancer given the detailed smoking histories. SOURCE OF DATA AND MODEL PARAMETERS--The smoking prevalence figures were taken from work by Harris who calculated them using data collected in the Health Interview Survey. The parameters of the multistage model were taken from Whittemore who fitted the model to several sets of smoking and lung cancer data. MAIN RESULTS--The smoking model was used to construct detailed smoking histories of the US white male population from 1900 to 1985. In turn the multistage model was used to predict age and cohort specific smoking induced lung cancer mortality rates over this period. These results were compiled to predict the overall age adjusted trend in smoking induced lung cancer from 1970 to 1985. The model predicts a 12% decline in smoking induced lung cancer for this group over the 15 year period. CONCLUSIONS--The model calculations predict a 12% decline in smoking induced lung cancer for this group, during a period when the actual total rate of lung cancer increased by 26%. Taken together with the decline in average tar content in cigarettes over this period, and the relatively constant dose rate among smokers, these results strongly suggest that the recent increase in lung cancer among white males in the USA is due entirely or in large part to factors other than cigarette smoking.