Personal NO2 exposures of preschool children in Helsinki

Weekly personal NO2 exposures of 246 children aged 3-6 years were measured with Palmes tubes during 13 weeks in winter and spring in 1991. Measurements were made in eight day-care centers in the downtown and suburban areas of Helsinki, Finland. At the same time, inside and outside NO2 concentration of the day-care centers and the ambient air fixed site measurements were conducted. Palmes tubes were found to be applicable for NO2 exposure measurements of preschool children, but rather high sample losses could be expected. The geometric mean of personal NO2 exposure levels of 13-week period was 26.5 micrograms/m3 in the downtown and 17.5 micrograms/m3 in the suburban area. Gas stove and smoking at home increased significantly personal exposure to NO2. The weekly population NO2 exposure correlated rather poorly with the fixed site ambient air NO2 levels (R2 = 0.37), but much better with the NO2 levels inside and outside the day-care centers (R2 = 0.88 and 0.86). In the suburban and downtown groups the between children variations in the NO2 exposures were only 14% and 28% of the total variations, which were dominated by the within child variation. Stationary measurements at the ambient air fixed sites and inside and outside the day-care centers explained the variation in personal exposures of the children well during the spring, but not during the winter. A regression model, where data from outside day-care center measurements, fixed ambient air monitors, residential area and home characteristics (i.e., gas stove, smoking inside at home, type of dwelling) were included, explained 32% of the personal NO2 exposure variation in winter and 67% in spring. In the absence of personal exposure measurements, both stationary measurements and questionnaire information are useful in estimating variations in personal exposures.     

PARATI--a dynamic model for radiological assessments in urban areas. Part I. Modelling of urban areas, their contamination and radiation fields

The structure and mathematical model of PARATI, a detailed computer programme developed for the assessment of the radiological consequences of an accidental contamination of urban areas, is described with respect to the scenarios used for the estimation of exposure fields in a village or town, the models for the initial and secondary contamination with the radionuclide 137Cs, the concepts for calculating the resulting radiation exposures and the changes with time of the contamination and radiation fields. Kerma rates at various locations in tropical urban areas are given, and the contribution of different contaminated surfaces to these rates after dry or wet deposition are discussed.     

Paraquat Exposure of Knapsack Spray Operators on Banana Plantations in Costa Rica

A study of occupational exposure to paraquat was performed among 11 knapsack spray operators at banana plantations in Costa Rica. External and internal exposures were quantified and determinants of exposure identified by measurements, observations, and interviews. Dermal exposure was measured with skin pads, respiratory exposure by personal air sampling, and internal exposure by urine sampling. The wrists, back, and legs were the areas with the highest levels of dermal exposure. Respiratory exposures appeared to be strongly influenced by differences between days, while dermal exposures varied mostly due to differences between plantations. The use of protective clothing did not effectively protect against dermal exposures. Both respiratory and dermal exposures were significantly related to internal exposures, and both should be considered possible routes for systemic absorption of paraquat. It cannot be excluded that measurable levels of exposure can lead to acute as well as chronic health effects. Furthermore, due to poor conditions within the working environment, the spray operators are continuously at risk for high exposures that could lead to severe intoxication, and therefore a strategy for control of exposure is necessary.     

Quantification of historical exposures in occupational cohort studies

Relatively few investigators have estimated quantitative exposure levels in epidemiologic studies, and, for those that have, few have discussed the strengths and weakness of their estimation method with respect to other methods. This paper reviews the steps for developing quantitative exposure estimates that have been used in published studies. First, the qualitative considerations to be evaluated in the selection of the agent to be estimated (i.e., the disease mechanism, the effects of exposure mixtures and interactions, the physical state of the agent, and the routes of exposures) are discussed. Considerations for developing exposure groups are then presented, including work history and exposure information characteristics, the homogeneity of exposures within exposure groups, the exposure estimation method, and the disease risk analyses to be performed. The various exposure estimation approaches are reviewed for their strengths and weaknesses, including the calculation of the mean exposures from existing exposure measurements, statistical models, measurement data from surrogate exposures, and professional judgment. Recommendations for future studies are provided.     

An estimate by two methods of thyroid absorbed doses due to BRAVO fallout in several Northern Marshall Islands

Estimates of the thyroid absorbed doses due to fallout originating from the 1 March 1954 BRAVO thermonuclear test on Bikini Atoll have been made for several inhabited locations in the Northern Marshall Islands. Rongelap, Utirik, Rongerik and Ailinginae Atolls were also inhabited on 1 March 1954, where retrospective thyroid absorbed doses have previously been reconstructed. The current estimates are based primarily on external exposure data, which were recorded shortly after each nuclear test in the Castle Series, and secondarily on soil concentrations of 137Cs in samples collected in 1978 and 1988, along with aerial monitoring done in 1978. The external exposures and 137Cs soil concentrations were representative of the atmospheric transport and deposition patterns of the entire Castle Series tests and show that the BRAVO test was the major contributor to fallout exposure during the Castle series and other test series which were carried out in the Marshall Islands. These data have been used as surrogates for fission product radioiodines and telluriums in order to estimate the range of thyroid absorbed doses that may have occurred throughout the Marshall Islands. Dosimetry based on these two sets of estimates agreed within a factor of 4 at the locations where BRAVO was the dominant contributor to the total exposure and deposition. Both methods indicate that thyroid absorbed doses in the range of 1 Gy (100 rad) may have been incurred in some of the northern locations, whereas the doses at southern locations did not significantly exceed levels comparable to those from worldwide fallout. The results of these estimates indicate that a systematic medical survey for thyroid disease should be conducted, and that a more definitive dose reconstruction should be made for all the populated atolls and islands in the Northern Marshall Islands beyond Rongelap, Utirik, Rongerik and Ailinginae, which were significantly contaminated by BRAVO fallout.     

Standardized management of patients and employees exposed to pertussis

Waning pertussis immunity and spread of pertussis by asymptomatic adults contributes to increased pertussis exposures of vulnerable children. The Santa Clara Valley Medical Center had 49 pertussis exposures between July 1, 1989, and June 30, 1997, which originated in pediatric units or clinics and had an impact on the Employee Health Service (EHS) and Emergency Department (ED). We have developed a standardized protocol for management of employees and patients exposed to pertussis. The protocol includes a checklist for infection control staff; memoranda to exposed units conveying exposure information, instructions for employees to report to EHS or ED, and disease symptom information; written guidelines for physician management of patient exposures (prophylaxis and isolation) and EHS or ED management of employee exposures; and prophylaxis recommendations. We allow exposed employees to work while wearing a mask (worn until 5 days of prophylaxis are completed or for the entire potential contagious period if prophylaxis was refused). Employees who develop pertussis are restricted from work. Our protocol and standardized forms provide consistent management of pertussis exposures in both patients and employees.     

Industrial hygiene aspects of a sampling survey at a bleached-kraft pulp mill in British Columbia

To validate exposure estimates used to investigate correlations between exposure and cancer risk, 1678 personal measurements were collected for 46 job titles during 73 day shifts at a bleached-kraft pulp mill. Measurements included shift-long average and short-term exposures to carbon monoxide, chlorine dioxide (ClO2), and hydrogen sulfide; and shift-long average exposures to calcium oxide and wood dust (WD). Overall results indicate low levels of exposure with a few noteworthy exceptions. Although ClO2 was the exclusive bleaching agent, 77 area samples indicated that chlorine (Cl2), not ClO2 was present in all areas apart from the chemical preparation area (chem-prep) and during a pulp spill. The highest shift-long exposures to Cl2 were measured in the chip yard and are attributed to uncontrolled stack emissions. Finally, WD samples collected from several laborers significantly exceeded regulatory limits, with the highest exposures measured in the steam and recovery area. For short-term exposures to ClO2 in chem-prep, 12 of 17 data-logging electro-chemical sensor sample results showed at least one peak that exceeded the short-term exposure limit of 0.3 ppm. The use of data-logging equipment quantified short-term exposures that previously had been characterized only anecdotally. The peaks were correlated with tasks and upset conditions and, given their transient nature, these exceedances could not have been detected using shift-long average-based sampling devices. Since the respiratory effects of significant short-term exposures to irritant gases such as Cl2 and ClO2 are well-documented, data-logging instruments are necessary to characterize exposures in the pulp and paper industry.     

Plant exposures ... a national profile of the most common plant genera

Plant exposures are the 4th most common cause of poisoning and 85% of those exposures involve the pediatric population. The large number of plant-related exposures and the lack of knowledge about plant toxicity has led to plant paranoia and considerable educational efforts to reduce the number of exposures. These efforts are often dictated by misconceptions and folklore. American Association of Poison Control Centers (AAPCC) data on all plant exposures for the years 1985-1994 were electronically analyzed by plant genus to establish a frequency distribution of all plant exposures in the United States. A total of 912,534 plant exposure cases were analyzed to tabulate the top 100 plant exposures. Philodendron spp were the most common exposures, followed by Dieffenbachia spp, Euphorbia spp, Capsicum spp and Ilex spp. Plant exposures are very common and poison information centers devote significant clinical service and educational effort to manage these exposures and enhance the public's awareness. Awareness of specific plant species and exposure frequency in a poison center region can serve as a basis for staff education and as the cornerstone for the development of appropriate information in poison prevention and education brochures. This can direct better utilization of poison center financial resources.     

Paradoxical enhancement of learned fear.

Conducted 2 experiments to demonstrate that presentation of the CS alone, after conditioning, can enhance learned fear. In Exp. I, groups of 12 Holtzman albino rats received 0-, 1/2-, 5-, 15-, or 50-min postconditioning exposure to the apparatus (the CS) in which they had previously been shocked. Results suggest that the 5-min exposure group was more fearful than the nonexposed controls. In Exp. II, 32 male Holtzman albino weanling rats were conditioned to fear 1 compartment in a shuttle box, followed 2 wk. later by interpolated exposures to the fear cues alone for 0, 30, 60, or 300 sec. 30- and 60-sec exposures produced significantly more spatial avoidance than 0- and 300-sec exposures. (34 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Methods development for epidemiologic investigations of the health effects of prolonged ozone exposure. Part II. An approach to retrospective estimation of lifetime ozone exposure using a questionnaire and ambient monitoring data (California sites)

An extensive body of data supports a relation between acute exposures to ambient ozone and the occurrence of various acute respiratory symptoms and changes in measures of lung function. In contrast, relatively few data are available on the human health effects that result from long-term exposure to ambient ozone, Current efforts to study long-term ozone-related health effects are limited by the methods available for ascertaining lifetime exposures to ozone. The present feasibility study was undertaken as part of the Health Effects Institute's Environmental Epidemiology Planning Project (Health Effects Institute 1994) to (1) determine whether, in the context of an epidemiologic study, reliable estimates can be obtained for lifetime exposures to ozone by combining estimates from lifetime residential histories, typical activity patterns during life, and residence-specific ambient ozone monitoring data; (2) identify the minimum data required to produce reliable estimates of lifetime exposure; and (3) analyze the relations between various estimates of lifetime ozone exposure and measures of lung function. A convenience sample of 175 first-year students at the University of California, Berkeley, who lived all of their lives in selected areas of California (the Los Angeles Basin or the San Francisco Bay Area), were studied on two occasions (test and retest or test sessions 1 and 2), five to seven days apart. Residential and lifestyle data were obtained from a questionnaire: residence-based ambient ozone exposure values were assigned by interpolation of ambient ozone monitoring data to residential locations. Estimated lifetime exposure was based on average ozone levels between 10 a.m. and 6 p.m. and hours of exposure to ozone concentrations greater than 60 parts per billion (ppb). "Effective" lifetime exposure to ozone was based on a weighted average of estimated time spent in different ambient ozone environments as determined by different combinations of activity data. Pulmonary function was evaluated with flows and volumes from maximum expiratory flow-volume curves and slope of phase III of the single-breath nitrogen washout (SBNW) curves. Although the test-retest reliability of the residential history was acceptably high only for first and second residences, most of the unreliability for other residences came from residences occupied for relatively short durations. Therefore, the test-retest reliability of estimated lifetime exposure to ozone was high, with intraclass correlations greater than 0.90 for all approaches evaluated. Multiple, linear regression analyses showed a consistently negative relation between estimates of lifetime exposure to ozone and flows that reflect the physiology of pulmonary small airways. No relation was observed between lifetime ozone exposure and forced expiratory volume or the slope of phase III, and the relation between lifetime exposure and forced expiratory volume in one second was inconsistent. The results of the flow measures were unaffected by the method used to estimate lifetime exposure and gave effect estimates that were nearly identical. The data from this study indicate that useful and reproducible estimates of lifetime ozone exposure can be obtained in epidemiologic studies by using a residential history. However, the total burden of ozone to which the subjects were exposed cannot be determined accurately from such data. Nonetheless, the estimates so obtained appear to be associated with alterations in pulmonary function that are consistent with the predicted site of maximum effect of ozone in the human lung.     

Novel popout: Empirical boundaries and tentative theory.

Observers received glimpses of 4-word arrays and were probed for the locations of particular words. Familiar words were repeated across arrays but novel words were not. Accuracy was higher for familiar than for novel arrays, but this baseline difference was diminished when a single novel word appeared with 3 familiar words. In these arrays, accuracy rose above baseline for novel words, defining novel popout (NPO), and fell below baseline for familiar words, defining familiar sink-in (FSI). In Exps 1–4, NPO remained intact and FSI actually increased as duration of array exposure was reduced from 200 msec to as brief as 33 msec. At brief exposures, even familiar words popped out from fields in which they had never before appeared. NPO is attributed to the distribution of locations associated with bottom-up-top-down mismatches. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychosocial, behavioral, and health factors related to menopause symptomatology

California Proposition 65 (Prop65) provides a mechanism by which the manufacturer may perform a quantitative risk assessment to be used in determining the need for cancer warning labels. This paper presents a risk assessment under this regulation for professional and do-it-yourself insulation installers. It determines the level of insulation glass fiber exposure (specifically Owens Corning's R-25 PinkPlus with Miraflex) that, assuming a working lifetime exposure, poses no significant cancer risk under Prop65's regulations. "No significant risk" is defined under Prop65 as a lifetime risk of no more than one additional cancer case per 100,000 exposed persons, and nonsignificant exposure is defined as a working lifetime exposure associated with "no significant risk." This determination can be carried out despite the fact that the relevant underlying studies (i.e., chronic inhalation bioassays) of comparable glass wool fibers do not show tumorigenic activity. Nonsignificant exposures are estimated from (1) the most recent RCC chronic inhalation bioassay of nondurable fiberglass in rats; (2) intraperitoneal fiberglass injection studies in rats; (3) a distributional, decision analysis approach applied to four chronic inhalation rat bioassays of conventional fiberglass; (4) an extrapolation from the RCC chronic rat inhalation bioassay of durable refractory ceramic fibers; and (5) an extrapolation from the IOM chronic rat inhalation bioassay of durable E glass microfibers. When the EPA linear nonthreshold model is used, central estimates of nonsignificant exposure range from 0.36 fibers/cc (for the RCC chronic inhalation bioassay of fiberglass) through 21 fibers/cc (for the i.p. fiberglass injection studies). Lower 95% confidence bounds on these estimates vary from 0.17 fibers/cc through 13 fibers/cc. Estimates derived from the distributional approach or from applying the EPA linear nonthreshold model to chronic bioassays of durable fibers such as refractory ceramic fiber or E glass microfibers are intermediate to the other approaches. Estimates based on the Weibull 1.5-hit nonthreshold and 2-hit threshold models exceed by at least a factor of 10 the corresponding EPA linear nonthreshold estimates. The lowest nonsignificant exposures derived in this assessment are at least a factor of two higher than field exposures measured for professionals installing the R-25 fiberglass insulation product and are orders of magnitude higher than the estimated lifetime exposures for do-it-yourselfers.     

Stimulus recognition may mediate exposure effects.

R. L. Moreland and R. B. Zajonc (see record 1979-23545-001) presented stimuli with differential numbers of exposures to Ss and obtained measures of affect (e.g., ratings of liking) and ratings of familiarity. Exposure frequency and ratings of familiarity were both significant predictors of affect in a multiple regression equation. Moreland and Zajonc concluded that there are 2 independent effects, and thus the exposure effect could not be explained by a stimulus recognition factor alone. However, the present article argues that these results can be explained by the theory that exposure frequency affects a single mediator that is imperfectly correlated with ratings of familiarity and affect. Thus, the null hypothesis that recognition mediates the exposure effect cannot be refuted by the partial correlation and regression analyses of Moreland and Zajonc. (7 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Accidental needlesticks in the phlebotomy service of the Department of Laboratory Medicine and Pathology at Mayo Clinic Rochester

OBJECTIVE: To determine the change in accidental needlestick rates in the Phlebotomy Service at Mayo Clinic Rochester and to identify safety practices implemented from 1983 through 1996. MATERIAL AND METHODS: We retrospectively reviewed yearly Phlebotomy Service accidental needlestick rates from 1983 through 1996. Interviews were conducted with representatives of the Infection Control Committee and the management team for the Phlebotomy Service, and minutes of meetings of these two groups were reviewed to identify implemented safety improvements that may have had an effect on accidental needlestick exposures. RESULTS: Accidental needlestick exposures in the Phlebotomy Service declined from a high of 1.5/10,000 venipunctures to 0.2/10,000 venipunctures. Several safety improvements were made during that time, including the implementation of a one-handed recapping block, change to single-use evacuated tube holders, increased number and improved locations of disposal containers for needles, implementation of resheathing needles and retractable capillary puncture devices, discontinuation of the practice of changing needles before inoculation of blood culture bottles, increased emphasis on safety for new and experienced phlebotomists, and improved exposure reporting tools. CONCLUSION: We believe that the decrease in our accidental needlestick exposure rate is correlated with the changes in education, practices, and products that we have implemented.     

Short-term versus long-term effects of adrenal hormones on behaviors.

Hypothesizes that short-term exposures to stress facilitate performances of serially repetitive, overlearned tasks and impair performances of perceptual restructuring tasks, while long-term exposures to stress produce the opposite behavioral effects. These effects are attributed, in part, to the length of exposure of the central nervous system to stress-elicited adrenal hormones (epinephrine and cortisol). Short-term exposures are believed to induce states of central adrenergic dominance that favor performances of serially repetitive, overlearned tasks at the expense of perceptual restructuring tasks. Longer exposures are thought to result in a shift to central cholinergic dominance that favors the opposite pattern of performances. A physiological model is presented that accounts for the shift from central adrenergic to central cholinergic dominance. Experimental procedures derived from the model promote the reversal of some of the behavioral and physiological effects of a long-term stressor. (5 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of six respirator fit-test methods with an actual measurement of exposure in a simulated health care environment: Part II--Method comparison testing

This article, the second in a series of three, describes the method comparison testing portion of a study conducted to compare the fit factors from six quantitative fit-tests (QNFT) with a measure of a respirator wearer's actual exposure assessed by end-exhaled air analysis for 1,1,2-trichloro-1,2,2-trifluoroethane (Freon-113) under the same conditions. The six QNFT methods were (1) continuous low flow, flush probe; (2) continuous high flow, deep probe (CHD); (3) exhalation valve discharge (EVD); (4) controlled negative pressure; (5) 10-minute Ambient Aerosol 1 (AA1); and (6) 30-minute Ambient Aerosol 2. The first three methods utilized corn oil and a forward light scattering photometer. The last two methods used the TSI Portacount. Respirators used in the study were both disposable and elastomeric organic vapor/high efficiency half-masks. The characterization equations from the preliminary research (described previously) were used to determine the actual exposure to Freon-113 during the method comparison testing. The fit factors resulting from the QNFT methods were then individually correlated with the Freon-113 exposures using the coefficient of determination, R2. The lowest R2 value, 0.20, was found with the EVD method. The highest R2 values, 0.81 and 0.78, were associated, respectively, with the CHD and AA1 methods. This study suggests that some QNFT methods may be used to estimate actual respirator performance under laboratory conditions.     

CO2 and Nd:YAG laser-induced pulmonary parenchymal lung injury in a rabbit model

Laser exposure of the pulmonary parenchyma during treatment of emphysema and other clinical indications causes acute lung injury. Animal investigations are needed to understand and control laser-induced lung injury. We hypothesized that lung injury is deeper from Nd:YAG laser exposures than CO2 exposures because of deeper penetration of Nd:YAG wavelength light. We compared the temporal evolution of histologic injury in rabbits resulting from continuous mode shallow CO2 and Nd:YAG laser pulmonary parenchymal exposures applied in rabbits. Forty-six New Zealand white (NZW) rabbits underwent treatment with CO2 laser (n=18), Nd:YAG laser (n=18), or sham thoracotomy control (n=10) to the visceral pleural surface using 1 min of exposure (5 watts, defocused to 70 W/cm2 power density for both lasers). Animals were killed at 0, 4, 7, 21, and 49 d after exposure. Lung injury, similar to that seen clinically in humans, developed in all laser-treated animals. Injury progressed from ischemia and vascular congestion, to edema and necrosis, followed by pleural and parenchymal fibrosis. The acute injury was qualitatively distinct and slightly deeper in CO2 than Nd:YAG-treated animals (p<0.02) despite the shallower depth of penetration of the CO2 laser. These findings may imply that higher absorption coefficient for CO2 laser energy results in greater focal temperatures and injury in the areas of direct exposure, and suggest that Nd:YAG laser exposure at these settings may cause shallower injury than CO2 lasers in humans undergoing clinical treatment.     

Review of health consequences from high-, intermediate- and low-level exposure to organophosphorus nerve agents

Short and long-term health effects from exposure to organophosphorus (OP) military and insecticidal nerve agents are evaluated based on the abundant scientific literature published over five decades on health effects in humans (from human experimentation and occupational exposures) and in laboratory animals. Four distinct health effects are identified: acute cholinergic toxicity; organophosphate-induced delayed neuropathy (OPIDN); subtle long-term neuropsychological and neurophysiological effects; and a reversible muscular weakness called 'intermediate syndrome'. Some effects are subtle and difficult to differentiate from health effects caused by other diseases or occupational exposures. Each effect has data suggesting threshold exposure levels below which it is unlikely to be clinically detectable. Therefore, meaningful interpretation of human and animal studies requires rigid exposure characterization. Because precise exposure levels are often difficult to reconstruct, a system for characterizing exposure is proposed based upon observed initial acute signs and symptoms, as high-level (definitive cholinergic poisoning); intermediate-level (threshold cholinergic effects including miosis, rhinorrhea or clinically measurable depression of cholinesterase); and low-level (no immediate clinical signs or symptoms) exposure. Threshold exposure levels for known long-term effects from OP nerve agent are at or above intermediate-level exposure. Long-term health effects seen at intermediate-level exposures or in many survivors of high-level exposure are subtle, detectable in exposed populations but not individuals, and not reported in individuals experiencing low-level exposure alone. Co-exposure to other pharmaceutical agents may promote or protect against health effects from OP nerve agents, but qualitatively they are the same effects seen with OP nerve agents alone. Thus, the system for characterizing exposure based on initial acute effects is also useful for evaluating health outcomes from co-exposure to OP nerve and other agents.     

Misclassification model for person-time analysis of automated medical care databases

A misclassification model is presented for the assessment of bias in rate ratios estimated by person-time analyses of automated medical care databases. The model allows for misclassification of events and person-time and applies to both differential and nondifferential errors. The focus is on medical care exposures that occur at discrete points in time (e.g., vaccinations) and on adverse events that are closely associated in time. Bias corrections for rate ratios and binomial tests of equality of event rates during exposed and unexposed person-time are developed and illustrated. For nondifferential under- or over-ascertainment of events, the observed rate ratio (r) is unbiased at the null hypothesis (true rate ratio R = 1), negatively biased when R > 1, and positively biased when R < 1 (i.e., biased toward the null). Differential under-ascertainment of unexposed events and differential over-ascertainment of exposed events positively bias r when R = 1. Differential event sensitivities cause larger biases in rate ratios than differential false event rates. False positive exposures bias observed event rate ratios more than false negative exposures. Biases are small when event sensitivities are nondifferential and when less than 10% of database exposures and events are false. The usefulness of the model for critical sensitivity analysis is illustrated by an example from a linked database study of childhood vaccine safety. Greater dissemination of data quality assessments, sensitivity analyses, and methods used to supplement automated databases are needed to further our understanding of the appropriate role of medical care databases in epidemiologic research.