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PubMed2006

Chemical characteristics and origins of nitrogen-containing organic compounds in PM2.5 aerosols in the Lower Fraser Valley.

Some nitrogen-containing organic compounds (NOCs) in PM2.5 aerosols in forest, tunnel, urban, rural, and mixed forest/ urban areas in the Lower Fraser Valley (LFV), British Columbia, Canada, were measured to assess their chemical characteristics, temporal and spatial distributions, and origins. The levels of E-caprolactam, isoindole-1,3-dione, benzothiazolone, and N-butyl-benzensulfonamide showed significant differences among the sites, with the highest level at the mixed forest/urban site, indicating that aerosols at this site were impacted by chemical manufacturing activities. N,N-diethyl-m-toluamide (deet) was detected at all locations but was highest in the forest area, demonstrating a widespread usage as an insect repellent in the LFV and at camps at the forest site. Alkyl amides, tracers from wood burning and cooking, ranging from C6 to C20 including two unsaturated amides, hexadecenamide, and 9-octa-decenamide, were detected at all sites. Three patterns of carbon number distributions of alkyl amides varied with location and time, and were mainly impacted by biomass burning or cooking compared to levoglucosan and cholesterol in the LFV. Ratio of oleamide to stearamide (C18:1/C18:0) was discussed as a potential indicator for determining "age" or transport range of biomass combustion plumes.

Air Pollutants↗
PubMed2002

Celastraceae sesquiterpenoids: biological activity and synthesis.

Plant extracts of the Celastraceae have been used for centuries throughout South America and China as insect repellents and insecticides in traditional agriculture, and also for the treatment of a plethora of medical ailments from stomach complaints and fever to rheumatoid arthritis and cancer. Many of the medicinally interesting properties associated with these crude preparations have now been attributed to a large family of highly oxygenated sesquiterpenoids based on a tricyclic dihydroagarofuran skeleton. In this article, the structural diversity and range of biological activities associated with this intriguing class of natural products are examined with a view to stimulating interest in their total synthesis. Existing synthetic endeavours towards their synthesis are also evaluated.

Cell Division↗
PubMed2002

Personal protection against mosquitoes in Dar es Salaam, Tanzania, by using a kerosene oil lamp to vaporize transfluthrin.

The effectiveness of a cheap and easy method of household protection against Culex quinquefasciatus Say and other mosquitoes (Diptera: Culicidae) was investigated in Dar es Salaam, Tanzania. Kerosene-burning lamps (korobois) were modified to heat and vaporize transfluthrin, a volatile pyrethroid insecticide. When transfluthrin was added to fuel of the lamp, protection against biting was poor unless a very high concentration of insecticide was used. A modified lamp (= vaporizing koroboi) was designed to overcome this problem by mixing the insecticide with vegetable oil and heating it to 120 degrees C in a tin held just above the flame. The concentration of 0.1% transfluthrin in vegetable oil gave 50-75% reduction in biting, a similar degree of protection to that obtained from burning a mosquito coil containing a synthetic pyrethroid (0.25% d-allethrin) and significantly better protection than a locally bought coil (brand 'White Crane', probably containing DDT). Greater protection (consistently > 90%) was achieved with a higher concentration of transfluthrin (0.5%) in the vegetable oil. This modified lamp is simple, cheap and employs locally available technology. With further development, and due regard to inhalation toxicity of the vaporized materials, it may offer a more cost-effective alternative to a mosquito coil as a means of personal protection, and a useful complement to a net for the early part of the evening before bedtime.

Animals↗
PubMed1995

Ehrlichiosis in a golf-oriented retirement community.

BACKGROUND: Ehrlichiosis due to Ehrlichia chaffeensis usually occurs sporadically or in small clusters, with an annual incidence estimated at 3 to 5 cases per 100,000 population in areas of endemic disease. The putative principal vector is the Lone Star tick (Amblyomma americanum). We investigated an outbreak of ehrlichiosis that occurred in June 1993 among members of a golf-oriented retirement community (community A) in Tennessee. The community is densely wooded and borders a wildlife-management area where deer are numerous. METHODS: We conducted a case-control study, using medical-history reviews, serologic testing, and testing with the polymerase chain reaction for E. chaffeensis infection. We also surveyed a sample of 10 percent of the households in community A and in another golf-oriented community (community B) more than 20 miles (32 km) from the wildlife-management area. Survey participants completed a questionnaire and provided specimens for serologic testing. In both communities, searches for ticks were undertaken. RESULTS: Eleven cases of symptomatic ehrlichiosis were identified in the case-control study, 10 of which were in community A (attack rate, 330 per 100,000). Of 311 surveyed residents of community A, 12.5 percent had serologic evidence of past E. chaffeensis infection, as compared with 3.3 percent of 92 in community B (relative risk in community A as compared with community B, 3.9; 95 percent confidence interval, 1.2 to 12.2). The risk of infection was associated with tick bites, exposure to wildlife, golfing, and among golfers, retrieving lost golf balls from the rough. Persons who never used insect repellent were more likely to have had infection than persons who did. In community A, thousands of Lone Star ticks were found; in community B, only three ticks were found. CONCLUSIONS: The high rate of E. chaffeensis infection in community A resulted from its proximity to a wildlife reserve. When outdoor recreational activities are common and concentrations of ticks are high, outbreaks of arthropod-borne zoonoses can be anticipated.

Adolescent↗
PubMed1997

Effect of environmental conditions on the penetration of benzene through human skin.

The in vitro penetration of [14C]benzene through freshly prepared human skin was examined under a variety of skin conditions associated with swimming and bathing. The experimental system utilized a recirculating donor solution and a flow-through receiver solution, and was modified to accommodate the analysis of volatiles. The permeability coefficient of 0.14 cm/h under standard conditions at 26 degrees C was found to increase to 0.26 cm/h at 50 degrees C and decrease to 0.10 cm/h at 15 degrees C. Storage of the skin at- 20 degrees C did not affect the penetration of benzene. Application of baby oil, moisturizer, or insect repellant to the skin before exposure under standard conditions did not affect the flux of benzene, but a significant increase was observed when the skin was pretreated with sunscreen (permeability coefficient 0.24 cm/h). These results suggest that risk assessment or exposure modeling for benzene and other environmental contaminants should account for appropriate changes in the environmental conditions when considering the dermal route of exposure.

Administration, Cutaneous↗
PubMed1999

Penetration of chloroform, trichloroethylene, and tetrachloroethylene through human skin.

In vitro dermal absorption was measured for three volatile organic compounds in dilute aqueous solution through freshly prepared and previously frozen human skin. The permeability coefficients at 26 degrees C for chloroform (0.14 cm/h) and trichloroethylene (0.12 cm/h) were similar but much larger than that for tetrachloroethylene (0.018 cm/h). Storage of the skin at -20 degrees C did not significantly affect the penetration of these chemicals. The dermal absorption of chloroform through freshly prepared human skin was not changed significantly by pretreatment of the skin with commonly used consumer products (moisturizer, baby oil, insect repellent, sunscreen); however, the permeability coefficient was found to increase from 0.071 cm/h at 11 degrees C to 0.19 cm/h at 50 degrees C. These data suggest that exposure estimates for chloroform and other contaminants in water should consider the appropriate exposure scenario to properly assess the dermal dose.

Adolescent↗
PubMed2004

Biological significance of essential oil of Zataria multiflora boiss.

The absolute from Zataria multiflora was explored for enzyme inhibition, insect repellent, and insecticidal activities. GC-MS of the absolute of fresh plant showed that thymol is the major constituent while carvacrol is the major constituent in the absolute of dried plant.

Animals↗
PubMed2006

Reported residential pesticide use and breast cancer risk on Long Island, New York.

Pesticides, common environmental exposures, have been examined in relation to breast cancer primarily in occupational studies or exposure biomarker studies. No known studies have focused on self-reported residential pesticide use. The authors investigated the association between reported lifetime residential pesticide use and breast cancer risk among women living on Long Island, New York. They conducted a population-based case-control study of 1,508 women newly diagnosed with breast cancer between August 1996 and July 1997 and 1,556 randomly selected, age-frequency-matched controls. Comprehensive residential pesticide use and other risk factors were assessed by using an in-person, interviewer-administered questionnaire. Unconditional logistic regression was used to calculate odds ratios and 95% confidence intervals. Breast cancer risk was associated with ever lifetime residential pesticide use (odds ratio = 1.39, 95% confidence interval: 1.15, 1.68). However, there was no evidence of increasing risk with increasing lifetime applications. Lawn and garden pesticide use was associated with breast cancer risk, but there was no dose response. Little or no association was found for nuisance-pest pesticides, insect repellents, or products to control lice or fleas and ticks on pets. This study is the first known to suggest that self-reported use of residential pesticides may increase breast cancer risk. Further investigation in other populations is necessary to confirm these findings.

Adult↗
PubMed1995

Dermatoses associated with travel to tropical countries: a prospective study of the diagnosis and management of 269 patients presenting to a tropical disease unit.

The full spectrum of skin diseases related to travel in tropical areas is unknown. We prospectively studied 269 consecutive patients with travel-associated dermatosis who presented to our tropical disease unit in Paris during a 2-year period. The median age of these patients was 30 years; 137 patients were male; 76% of the patients were tourists; 38% had visited sub-Saharan Africa; and 85% had been appropriately vaccinated against tetanus. Cutaneous lesions appeared while the patient was still abroad in 61% of cases and after the patient's return to France in 39%. The diagnosis was definite in 260 cases; 137 of these cases (53%) involved an imported tropical disease. The most common diagnoses were cutaneous larva migrans (25%); pyodermas (18%); pruritic arthropod-reactive dermatitis (10%); myiasis (9%); tungiasis (6%); urticaria (5%); fever and rash (4%); and cutaneous leishmaniasis (3%). Hospitalization was necessary in 27 cases (10%), with a median duration of 5 days (range, 2-21 days). Travelers should be advised on how to avoid exposure to the agents and vectors of infectious dermatoses. Travel first-aid kits should include insect repellents and antibiotics effective against bacterial skin infections.

Adolescent↗
PubMed2005

Neurological status of Australian veterans of the 1991 Gulf War and the effect of medical and chemical exposures.

BACKGROUND: Since the 1991 Gulf War, concerns have been voiced about the effects on the health of veterans of Gulf War related medical and chemical exposures. METHODS: Our cross-sectional study compared 1424 male Australian Gulf War veterans and a randomly sampled military comparison group (n = 1548). A postal questionnaire asked about the presence of current neurological type symptoms, medically diagnosed neurological conditions, and medical and chemical exposures. A neurological examination was performed as part of a physical assessment. RESULTS: Veterans have a higher prevalence of neurological type symptoms (ratio of means 1.4, 95% confidence interval (CI) 1.2-1.5). Although the odds ratio (OR) of lower limb neurological type symptoms and signs in veterans compared with the comparison group was increased (OR = 1.6, 95% CI 1.0-2.7), it was of borderline significance, and there was no difference between groups according to a Neuropathy Score based on neurological signs alone (ratio of means 1.1, 95% CI 0.9-1.3). The increased OR of neurological type symptoms and signs suggestive of a central nervous system disorder (OR = 1.8, 95% CI 1.0-3.1) was also of borderline significance. Veterans were not more likely to have self-reported medically diagnosed neurological conditions, or to have neurological type symptoms and signs suggestive of an anterior horn cell disorder (OR = 0.9, 95% CI 0.5-1.6). The total number of neurological type symptoms reported by veterans, but not the Neuropathy Score, was associated with Gulf War related exposures including immunizations and pyridostigmine bromide in dose-response relationships, anti-biological warfare tablets, solvents, pesticides, and insect repellents. CONCLUSIONS: This study shows increased reporting of neurological type symptoms in Gulf War veterans, but no evidence for increased neurological effects based on objective physical signs. There may be a number of factors, including information bias, relating to increased neurological type symptom reporting in veterans.

Adult↗
PubMed2005

A physiologically based pharmacokinetic model of organophosphate dermal absorption.

The rate and extent of dermal absorption are important in the analysis of risk from dermal exposure to toxic chemicals and for the development of topically applied drugs, barriers, insect repellents, and cosmetics. In vitro flow-through cells offer a convenient method for the study of dermal absorption that is relevant to the initial processes of dermal absorption. This study describes a physiologically based pharmacokinetic (PBPK) model developed to simulate the absorption of organophosphate pesticides, such as parathion, fenthion, and methyl parathion through porcine skin with flow-through cells. Parameters related to the structure of the stratum corneum and solvent evaporation rates were independently estimated. Three parameters were optimized based on experimental dermal absorption data, including solvent evaporation rate, diffusivity, and a mass transfer factor. Diffusion cell studies were conducted to validate the model under a variety of conditions, including different dose ranges (6.3-106.9 microg/cm2 for parathion; 0.8-23.6 microg/cm2 for fenthion; 1.6-39.3 microg/cm2 for methyl parathion), different solvents (ethanol, 2-propanol and acetone), different solvent volumes (5-120 microl for ethanol; 20-80 microl for 2-propanol and acetone), occlusion versus open to atmosphere dosing, and corneocyte removal by tape-stripping. The study demonstrated the utility of PBPK models for studying dermal absorption, which can be useful as explanatory and predictive tools that may be used for in silico hypotheses generation and limited hypotheses testing. The similarity between the overall shapes of the experimental and model-predicted flux/time curves and the successful simulation of altered system conditions for this series of small, lipophilic compounds indicated that the absorption processes that were described in the model successfully simulated important aspects of dermal absorption in flow-through cells. These data have direct relevance to topical organophosphate pesticide risk assessments.

Administration, Cutaneous↗
PubMed1997

A comparison of case-crossover and case-control designs in a study of risk factors for hemorrhagic fever with renal syndrome.

The case-crossover design is a new method for studying acute effects of transient exposures, in which cases serve as their own controls. To assess the validity, strengths, and weaknesses of the design, we used both the case-crossover method and the traditional case-control method of multivariate analysis with data collected from 196 cases and 295 hospital controls to study risk factors for hemorrhagic fever with renal syndrome in Korean soldiers. Both case-control and case-crossover methods showed that living in primitive field conditions, exposure to dust, and exposure to rodents were risk factors; use of insecticides or insect repellents was protective. Odds ratios from the case-crossover method were generally somewhat higher for risk factors and lower for protective factors. The case-crossover technique has great potential as a powerful, cost-effective way to assess risk factors for conditions such as infectious diseases and injuries, while avoiding some of the bias and logistical problems of traditional study designs.

Adult↗
PubMedDate not supplied

Childhood burns in camping and outdoor cooking accidents: a focus for prevention.

We have seen increasing numbers of children who present with serious burns related to camping and outdoor cooking, prompting this 5-year review. Of 34 children (21 boys and 13 girls), with an average age of 5.2 years (4 months to 17 years) and average burn size of 15% (1% to 98%) cared for (4 as outpatients and 30 as inpatients), there was one fatality (3%). Mechanisms of injury included falling into free pits, throwing flammables into grills or pits, placing hands on hot objects in or near a fire, walking or falling into hot embers from an extinguished fire, spills from insect repellant candies, tent fires, burning of paper eating utensils, and cooking scalds. We have initiated a directed prevention program with the regional state park systems.

Accident Prevention↗
PubMed2000

Deployment stressors and a chronic multisymptom illness among Gulf War veterans.

Unusual health problems have been reported by Gulf War (GW) veterans, but no single etiology has been linked to these illnesses. This study was conducted to determine the association between self-reported GW deployment stressors and an illness defined by a combination of fatigue, mood-cognition, and musculoskeletal symptoms. A total of 1002 GW veterans from this cross-sectional survey of four Air Force units completed a self-administered questionnaire that asked about symptoms, demographic and military characteristics, and stressors during deployment. Severe and mild-moderate illness was positively associated with self-reports of pyridostigmine bromide use, insect repellent use and belief in a threat from biological or chemical weapons. Injuries requiring medical attention were only associated with severe illness. These results suggest a link between self-reported chemical, emotional, and physical exposures, and GW veterans' illness. Further research is needed to determine physiological and psychological mechanisms through which such stressors could have contributed to this symptom complex.

Adult↗
PubMed2001

Rocky Mountain spotted fever and pregnancy: a case report and review of the literature.

The classic triad of fever, headache, and characteristic rash occurring 1 to 2 weeks after a tick bite in an endemic area should raise suspicions for Rocky Mountain spotted fever (RMSF). All providers with primary care responsibility for women should be familiar with the diagnosis and treatment of this illness. As a recent case illustrates, the diagnosis of Rocky Mountain spotted fever may be complicated by pregnancy. Several conditions of pregnancy have similar presentations to the initial, often nonspecific manifestations of RMSF. Although doxycycline is the recommended therapy for children and nonpregnant women, chloramphenicol remains the recommended therapy for women during pregnancy. The time of year, local prevalence, and patient's exposure history may be taken into account when deciding to treat during pregnancy. Vertical transmission of RMSF has not been documented in humans. Prevention of RMSF by avoidance of tick-infested areas or by the use of insect repellents and long clothing is recommended for all patients.

Adult↗
PubMed1979

Evaporation of diethyltoluamide from human skin in vivo and in vitro.

Relative evaporation and penetration of the insect repellent, N,N-diethyl-m-toluamide, has been measured by 3 methods, 2 in vivo and 1 in vitro. The evaporation rate 30 min after application was found to be similar by all 3 methods. At an applied dose of 0.25 microgram/cm2, 9.6% in vivo and 9.7% in vitro evaporated from the skin in the first hour after application. Although the techniques used produced similar results in vivo and in vitro for diethyltoluamide, studies are being conducted to further elucidate kinetics of loss by evaporation.

Benzamides↗
PubMed2001

Initial degradation of dimethylphthalate by esterases from Bacillus species.

Dimethylphthalate (DMP), one of the phthalate esters, is used in the manufacture of plasticizers, insect repellents, and synthetic fibers, and contributes to environmental pollution. In the present study, we report a novel bacterium belonging to the Bacillus sp., which has the ability to utilize DMP as the sole source of carbon. The esterases from the cell-free extract of the Bacillus de-esterified DMP. Native polyacrylamide gel electrophoresis showed the presence of four isoesterases designated Et1--4. The isoesterases Et-4 and Et-1 showed a higher preference towards DMP hydrolysis as compared with Et-2 and 3. A megaplasmid of about 60 kb was detected in this bacterium. The ability of this bacterium to utilize DMP as the sole source of carbon was lost upon plasmid curing. The isoesterases Et-1--4 were absent in the cell-free extracts of the cured bacterium. The results from our studies clearly demonstrate that de-esterification is the initial step in the degradation of DMP and the genes for these esterases seem to be harbored on the plasmid in this bacterium.

Bacillus↗