Reliably colonising broiler chickens with Campylobacter spp. using a litter-based method.

1. Chicken-associated Campylobacter spp. are the cause of most food poisoning cases in Europe. In order to study the host-pathogen interactions, a reliable and reproducible method of colonising chickens with the bacteria is required. 2. This study aimed to identify a more appropriate and less invasive method of colonisation (cf. gavaging) by seeding bedding material (litter) that commercial chickens are kept on with a mixture of Campylobacter spp., broth and faeces. 3. The first phase of the study tested the longevity of Campylobacter spp. recovery in seeded litter over 24 h: significantly more Campylobacter spp. was recovered at 0 or 3 h post-seeding than at 6 and 24 h post-seeding, indicating that the pathogen can survive to detectable levels for at least 3 h in this environment. 4. In the second phase, three groups of 10 broiler chickens (negative for Campylobacter spp. prior to exposure) were exposed at 21 days of age to one of three different Campylobacter jejuni and C. coli mixes (A, B, C), using the method above. At 28 days of age, birds were euthanised by overdose of barbiturate or cervical dislocation, and livers and caeca removed for Campylobacter spp. assessment. 5. All liver and 28/30 caeca samples tested positive for Campylobacter spp., with mix A and C giving higher counts in the caeca than mix B. The method of euthanasia did not affect Campylobacter spp. counts. 6. In conclusion, a successful method for reliably colonising broiler chickens with Campylobacter spp. has been developed which negates the need for gavaging and is more representative of how contamination occurs in the field.

Maternal age and asthma in Latino populations.

BACKGROUND: Younger maternal age at birth is associated with increased risk of asthma in offspring in European descent populations, but has not been studied in Latino populations. OBJECTIVES: We sought to examine the relationship between maternal age at birth and prevalence of asthma in a nationwide study of Latino children. METHODS: We included 3473 Latino children aged 8-21 years (1696 subjects with physician-diagnosed asthma and 1777 healthy controls) from five US centres and Puerto Rico recruited from July 2008 through November 2011. We used multiple logistic regression models to examine the effect of maternal age at birth on asthma in offspring overall and in analyses stratified by ethnic subgroup (Mexican American, Puerto Rican and other Latino). Secondary analyses evaluated the effects of siblings, acculturation and income on this relationship. RESULTS: Maternal age < 20 years was significantly associated with decreased odds of asthma in offspring, independent of other risk factors (OR = 0.73, 95% CI: 0.57-0.93). In subgroup analyses, the protective effect of younger maternal age was observed only in Mexican Americans (OR = 0.53, 95% CI: 0.36, 0.79). In Puerto Ricans, older maternal age was associated with decreased odds of asthma (OR = 0.65, 95% CI: 0.44-0.97). In further stratified models, the protective effect of younger maternal age in Mexican Americans was seen only in children without older siblings (OR = 0.44, 95% CI: 0.23-0.81). CONCLUSION AND CLINICAL RELEVANCE: In contrast to European descent populations, younger maternal age was associated with decreased odds of asthma in offspring in Mexican American women. Asthma is common in urban minority populations but the factors underlying the varying prevalence among different Latino ethnicities in the United States is not well understood. Maternal age represents one factor that may help to explain this variability.

The association of psychosocial screening and service provision in pediatric oncology: the Psychosocial Assessment Tool (PAT2.0) into clinical practice.

PURPOSE: Distress screening in oncology has been widely endorsed in recent years. However, current knowledge of the impact of screening on delivery of clinical psychosocial services is limited. This study investigated the association between screening and psychosocial services in the early period following diagnosis of childhood cancer. METHODS: The Psychosocial Assessment Tool (PAT2.0) was administered by clinical social workers in two pediatric oncology centers shortly following diagnosis. Psychosocial service activity in the first 8 weeks post diagnosis was collected via social work surveys and extraction of information from hospital databases. RESULTS: PAT2.0 and psychosocial service data were obtained for 89 families with a child newly diagnosed with cancer. Distribution of PAT2.0 risk categories was consistent with previous studies (57.3 % universal, 38.2 % targeted, 4.5 % clinical). Significant, weak to moderate correlations between PAT2.0 and social workers' estimates of psychosocial risk were observed. No significant differences in the amount of psychosocial services provided to families with "universal" versus "elevated" (i.e., targeted or clinical) risk were found. Number of days in hospital was strongly and positively associated with the amount of psychosocial services families received in the first 8 weeks following diagnosis. CONCLUSIONS: Psychosocial risk, as measured by the PAT2.0, and allocation of psychosocial services were not significantly associated in the early period following diagnosis. Further investigation is required to understand if differences emerge over time when psychosocial screening is implemented clinically. Development of clinical pathways of care needs to account for patients who may predominantly be treated in the outpatient setting.

Race, Calcineurin Inhibitor Exposure, and Renal Function After Solid Organ Transplantation.

BACKGROUND: Calcineurin-inhibitor (CNI)-induced nephrotoxicity frequently complicates transplantation. African-Americans are at a greater risk of renal failure than the general population. We investigated whether race was an effect modifier of the relationship between CNI exposure and kidney function after nonrenal solid organ transplantation. METHODS: This is a retrospective cohort study of 1609 patients who underwent initial nonrenal solid organ transplantation between January 2000 and June 2012. A central repository administrative database was queried electronically for demographics, comorbidities, and serial levels of tacrolimus, cyclosporine, and serum creatinine. Predictors of interest were total drug exposure of tacrolimus and cyclosporine (area under the concentration-time curve) and self-reported race. The outcome of interest was cumulative change in estimated glomerular filtration rate (GFR). RESULTS: There were 1109 patients treated with tacrolimus (271 African-Americans) and 500 patients treated with cyclosporine (113 African Americans). A decline in GFR over time was seen with total tacrolimus exposure (-1.3 mL/min/1.73 m(2) for every 5 ng/mL·year increase in tacrolimus) and total cyclosporine exposure (-1.1 mL/min/1.73 m(2) for every 50 ng/mL·year increase in cyclosporine). However, total CNI exposure effect on estimated GFR changes did not vary by race (P interaction was 0.9 for tacrolimus and 0.6 for cyclosporine). CONCLUSIONS: Total CNI exposure is associated with worsening kidney function among patients with nonrenal solid organ transplantation. However, African-American patients are not more vulnerable to chronic CNI-induced nephrotoxicity when compared to white patients.

Work-related stress and reward: an Australian study of multidisciplinary pediatric oncology healthcare providers.

OBJECTIVE: Managing staff stress and preventing long-term burnout in oncology staff are highly important for both staff and patient well-being. Research addressing work-related stress in adult oncology is well documented; however, less is known about this topic in the pediatric context. This study examined sources of work-related stress and reward specific to multidisciplinary staff working in pediatric oncology in Australia. METHOD: Participants were 107 pediatric oncology clinicians, including medical, nursing, and allied health staff from two Australian pediatric oncology centers. Participants completed an online survey using two newly developed measures: the work stressors scale-pediatric oncology and the work rewards scale-pediatric oncology. RESULTS: The most commonly reported sources of both stress and reward are related to patient care and interactions with children. Results indicated that levels of work-related stress and reward were similar between the professional disciplines and between the two hospitals. Regression analyses revealed no demographic or organizational factors that were associated with either stress or reward. CONCLUSIONS: Work-related stress and reward are not mutually exclusive; particular situations and events can be simultaneously stressful and rewarding for healthcare providers. Although patient care and interactions with children was found to be the most stressful aspect of working in this speciality, it was also the greatest source of reward. Results are discussed in relation to workplace approaches to staff well-being and stress reduction.

Parent perceptions of managing child behavioural side-effects of cancer treatment: a qualitative study.

BACKGROUND: Very little research has examined the role of parenting in managing behavioural side-effects of cancer treatment. The purpose of this paper was to explore parent perceptions of (a) parenting in the context of childhood cancer; (b) the parenting strategies used in the context of managing child behavioural side-effects of cancer treatment; and (c) the perceived impact that cancer-specific parenting strategies have on child behaviour. METHODS: Participants were 15 mothers of children aged 2-6 years in the maintenance phase of treatment for acute lymphoblastic leukaemia at the Royal Children's Hospital Children's Cancer Centre, Melbourne, Australia. Mothers participated in a one-on-one semi-structured telephone interview using an interview guide which included questions on parenting in the context of childhood cancer, specifically in relation to behavioural side-effects (problems with behaviour, sleep and eating) and any perceived impact cancer-specific parenting may have on the ill child. RESULTS: Many parents reported that following their child's cancer diagnosis, they had to implement a suite of 'new' strategies that 'pre-diagnosis' were used only in moderation, if at all. The most salient theme that emerged was parents' perception that their parenting became more lax since their child's diagnosis. Parents further reported specific parenting strategies for each of the main child behavioural side-effects of cancer treatment. CONCLUSION: Data from the current qualitative exploratory study highlight the role of specific parenting strategies in managing or assisting child behavioural side-effects of cancer treatment. Further quantitative research is needed to more fully examine the association between parenting and child behavioural outcomes in order to develop modifiable approaches to improving child behavioural side-effects in a paediatric oncology context.

Gene-based association identifies SPATA13-AS1 as a pharmacogenomic predictor of inhaled short-acting beta-agonist response in multiple population groups.

Inhaled short-acting beta-agonist (SABA) medication is commonly used in asthma patients to rapidly reverse airway obstruction and improve acute symptoms. We performed a genome-wide association study of SABA medication response using gene-based association tests. A linear mixed model approach was first used for single-nucleotide polymorphism associations, and the results were later combined using GATES to generate gene-based associations. Our results identified SPATA13-AS1 as being significantly associated with SABA bronchodilator response in 328 healthy African Americans. In replication, this gene was associated with SABA response among the two separate groups of African Americans with asthma (n=1073, P=0.011 and n=1968, P=0.014), 149 healthy African Americans (P=0.003) and 556 European Americans with asthma (P=0.041). SPATA13-AS1 was also associated with longitudinal SABA medication usage in the two separate groups of African Americans with asthma (n=658, P=0.047 and n=1968, P=0.025). Future studies are needed to delineate the precise mechanism by which SPATA13-AS1 may influence SABA response.

Efficient inference of local ancestry.

MOTIVATION: The inference of local ancestry of admixed individuals at every locus provides the basis for admixture mapping. Local ancestry information has been used to identify genetic susceptibility loci. RESULTS: In this study, we developed a statistical method, efficient inference of local ancestry (EILA), which uses fused quantile regression and k-means classifier to infer the local ancestry for admixed individuals. We also conducted a simulation study using HapMap data to evaluate the performance of EILA in comparison with two competing methods, HAPMIX and LAMP. In general, the performance declined as the ancestral distance decreased and the time since admixture increased. EILA performed as well as the other two methods in terms of computational efficiency. In the case of closely related ancestral populations, all the three methods performed poorly. Most importantly, when the ancestral distance was large or moderate, EILA had higher accuracy and lower variation in comparison with the other two methods. AVAILABILITY AND IMPLEMENTATION: EILA is implemented as an R package, which is freely available from the Comprehensive R Archive Network (http://cran.r-project.org/). CONTACT: jyangstat@gmail.com.

Campylobacter infection has different outcomes in fast- and slow-growing broiler chickens.

Campylobacter spp. are frequently carried by poultry, but they are not believed to cause significant disease in these animals. Modern poultry breeds have been selected to grow rapidly under intensive conditions, but recently, consumers have moved toward purchasing birds produced in higher welfare, free-range or organic systems. Birds reared in these systems tend to be a slower growing breed and are fed a different diet. Birds reared in such systems are stocked at a lower density compared with the standard conventional broilers, and they have access to environmental enrichment, such as perches. In previous research, these slower growing birds have been shown to have different levels of Campylobacter carriage in commercial rearing conditions, but the reasons for, and effect of, these different levels are unknown; is it the bird breed, diet, or environmental conditions? In this study, experimental flocks of fast- and slow-growing breeds of broiler chickens were reared to a standard commercial slaughter weight, with their weight gain being measured during the growing period. At 21 days, birds were either infected with Campylobacter jejuni or given a placebo as control. Cohorts of birds were euthanatized at various intervals, and samples were taken for examination for Campylobacter. The fast-growing birds gained weight more rapidly than the slow-growing birds. By 2 days postinfection (dpi), C. jejuni was detected in the caeca and by enrichment from the liver and spleen samples from both breeds of birds. Low-level colonization persisted in the spleen and liver samples but was undetectable by 28 dpi. Fast- and slow-growing birds did not show detectably different levels of Campylobacter carriage. Infection with C. jejuni affected the incidence of hock marks and pododermatitis in both breeds of birds, but the differences were greater with the fast-growing breed compared with the uninfected control birds. In addition, the incidence of pododermatitis was significantly higher in Campylobacter-positive fast-growing birds than in their slower-growing counterparts. The results show that infection with Campylobacter can have an indirect welfare effect on birds via increased incidence of hock marks and pododermatitis.

Enrichment culture can bias the isolation of Campylobacter subtypes.

Enrichment culture is often used to isolate Campylobacter. This study compared isolation of Campylobacter spp. from 119 broiler chicken environments from two farms, using Preston and modified Exeter (mExeter) and modified Bolton (mBolton) enrichments. mExeter was significantly more effective in isolating Campylobacter spp. from the environmental samples compared to Preston (P<0.001) and mBolton (P<0.04) broths but there was no significant difference between the latter two methods (P>0.05). Enrichment broth type did not affect isolation from chicken faecal or soil and litter samples. C. jejuni was isolated from significantly more environmental samples using mExeter broth compared to Preston (P<0.01) and mBolton (P<0.003) broths; there was no difference between the latter two methods or between all methods for detection of C. coli (P>0.05). Only C. coli was isolated from the soil and litter samples and although both C. jejuni and C. coli were recovered from the faecal samples there was no effect of using different enrichment broths. The majority of samples where the same species had been isolated yielded the same or closely related genotypes as defined by pulsed-field gel electrophoresis. Isolates recovered using Preston and mBolton broths were less genetically diverse than those from mExeter broth. We conclude that the enrichment method used affects both the number and species of Campylobacter isolated from naturally contaminated samples.

Expression of the familial cardiac valvular dystrophy gene, filamin-A, during heart morphogenesis.

Myxoid degeneration of the cardiac valves is a common feature in a heterogeneous group of disorders that includes Marfan syndrome and isolated valvular diseases. Mitral valve prolapse is the most common outcome of these and remains one of the most common indications for valvular surgery. While the etiology of the disease is unknown, recent genetic studies have demonstrated that an X-linked form of familial cardiac valvular dystrophy can be attributed to mutations in the Filamin-A gene. Since these inheritable mutations are present from conception, we hypothesize that filamin-A mutations present at the time of valve morphogenesis lead to dysfunction that progresses postnatally to clinically relevant disease. Therefore, by carefully evaluating genetic factors (such as filamin-A) that play a substantial role in MVP, we can elucidate relevant developmental pathways that contribute to its pathogenesis. In order to understand how developmental expression of a mutant protein can lead to valve disease, the spatio-temporal distribution of filamin-A during cardiac morphogenesis must first be characterized. Although previously thought of as a ubiquitously expressed gene, we demonstrate that filamin-A is robustly expressed in non-myocyte cells throughout cardiac morphogenesis including epicardial and endocardial cells, and mesenchymal cells derived by EMT from these two epithelia, as well as mesenchyme of neural crest origin. In postnatal hearts, expression of filamin-A is significantly decreased in the atrioventricular and outflow tract valve leaflets and their suspensory apparatus. Characterization of the temporal and spatial expression pattern of filamin-A during cardiac morphogenesis is a crucial first step in our understanding of how mutations in filamin-A result in clinically relevant valve disease.

Echocardiography in hypertrophic cardiomyopathy diagnosis, prognosis, and role in management.

Hypertrophic cardiomyopathy (HCM) is diagnosed on the basis of left ventricular (LV) hypertrophy for which there is insufficient explanation (e.g. mild hypertension or mild aortic stenosis with marked hypertrophy). Echocardiography is an invaluable tool in the diagnosis and follow-up of patients with HCM. Echocardiographic assessment requires a comprehensive assessment in several imaging planes with careful attention to correct beam alignment in order to minimize errors in the measurement of LV wall thickness and appropriate identification of hypertrophy with an unusual distribution.

Persistence of Campylobacter species, strain types, antibiotic resistance and mechanisms of tetracycline resistance in poultry flocks treated with chlortetracycline.

OBJECTIVES: The aim of this study was to investigate the persistence of Campylobacter species, strain types, antibiotic resistance and mechanisms of tetracycline resistance in poultry flocks treated with chlortetracycline. METHODS: Three commercially reared broiler flocks, naturally colonized with Campylobacter, were treated with chlortetracycline under experimental conditions. The numbers of Campylobacter isolated, and the species, flaA short variable region allele, and antimicrobial resistance of isolates were determined. RESULTS: For two of three flocks, tetracycline-resistant strains predominated prior to chlortetracycline exposure. Presence of the antibiotic had no discernible effect on the numbers or types of Campylobacter and the tetracycline-resistant strains persisted in numbers similar to those observed before treatment. With all flocks, some faecal samples were obtained that contained no Campylobacter, irrespective of exposure to chlortetracycline; this was more common as the birds grew older. For the third flock, tetracycline-resistant Campylobacter were in the minority of samples before and during exposure to chlortetracycline, but at sampling times after this, no resistant strains were found in the treated (or untreated) birds, irrespective of exposure to the antibiotic. All tetracycline-resistant isolates (MICs 16 to >128 mg/L) contained tet(O) and, for some isolates, this was transferable to Campylobacter jejuni 81116. The efflux pump inhibitor PAbetaN reduced the MICs of tetracycline for these isolates by 4-fold, suggesting that an intact efflux pump, presumably CmeABC, is required for high-level tetracycline resistance. CONCLUSIONS: Our data indicate that chlortetracycline treatment does not eradicate tetracycline-resistant Campylobacter spp. from poultry. However, if a low number of resistant isolates are present, then the antibiotic pressure appears insufficient to select such strains as the dominant population.

Mechanical stretch promotes alveolar epithelial type II cell differentiation.

Functional maturation of pulmonary alveolar epithelial cells is crucial for extrauterine survival. Mechanical distension and mesenchymal-epithelial interactions play important roles in this process. We hypothesized that mechanical stretch simulating fetal breathing movements is an important regulator of pulmonary epithelial cell differentiation. Using a Flexercell Strain Unit, we analyzed effects of stretch on primary cultures of type II cells and cocultures of epithelial and mesenchymal cells isolated from fetal rat lungs during late development. Cyclic stretch of isolated type II cells increased surfactant protein (SP) C mRNA expression by 150 +/- 30% over controls (P < 0.02) on gestational day 18 and by 130 +/- 30% on day 19 (P < 0.03). Stretch of cocultures with fibroblasts increased SP-C expression on days 18 and 19 by 170 +/- 40 and 270 +/- 40%, respectively, compared with unstretched cocultures. On day 19, stretch of isolated type II cells increased SP-B mRNA expression by 50% (P < 0.003). Unlike SP-C, addition of fibroblasts did not produce significant additional effects on SP-B mRNA levels. Under these conditions, we observed only modest increases in cellular immunoreactive SP-B, but secreted saturated phosphatidylcholine rose by 40% (P < 0.002). These results indicate that cyclic stretch promotes developmentally timed differentiation of fetal type II cells, as a direct effect on epithelial cell function and via mesenchymal-epithelial interactions. Expression of the SP-C gene appears to be highly responsive to mechanical stimulation.

Lice, nits, and school policy.

BACKGROUND: The epidemiology of head lice infestation is poorly understood. Many schools treat all children with nits as though they are contagious. Children with nits but no lice are often removed from school until they are treated and all visible nits are removed. OBJECTIVE: To investigate the probability that children with nits alone will become infested with lice. DESIGNS: Prospective cohort study. SETTING: Two metropolitan Atlanta elementary schools. PARTICIPANTS: A total of 1729 children were screened for head lice. Twenty-eight children (1.6%) had lice, whereas 63 (3.6%) had nits without lice. Fifty of the 63 children (79%) with nits alone completed follow-up. OUTCOME MEASURE: Conversion (ie, becoming infested with lice) within 14 days after initial screening. RESULTS: Nine of 50 children (18.0%) followed for nits alone converted. Although children who converted did not have significantly more nits than did nonconverters, having nits near the scalp was a risk factor for conversion. Seven of 22 children (31.8%) with >/=5 nits within one fourth inch of the scalp converted, compared with 2 of 28 children (7.1%) with fewer (relative risk: 4.45; 95% confidence interval: 1.03-19.35). This risk remained statistically significant after separately stratifying for sex, recent treatment, and total number of nits. CONCLUSIONS: Although having >/=5 nits within one fourth inch of the scalp was a risk factor for conversion, most children with nits alone did not become infested. Policies requiring exclusion from school and treatment for all children with nits alone are likely excessive. Instead, these children may benefit from repeated examination to exclude the presence of crawling lice.lice, pediculus, lice infestations, pediatrics, school.

Fluorous-phase soluble polymeric supports.

Fluorous phase soluble polymer supports derived from fluoroacrylate polymers are described. N-Acryloxysuccinimide-containing fluoroacrylate polymers were readily prepared from commercially available monomers. The activated acrylates so prepared were then converted into chelating and non-chelating ligands by amidation of the N-acryloxysuccinimide active ester residues. Phosphine ligands attached to these supports were used to prepare neutral and cationic rhodium(I) hydrogenation catalysts as well as palladium(0) catalysts. Similar substitution of pendant active ester groups to form hydroxamic acid ligands for metal sequestration is also feasible. Liquid/liquid extraction readily separated, recycled and reused these polymer-bound ligands and catalysts. While fluorous phase solubility could be attained with polymers containing only heptafluorobutyryl groups, selective solubility in a fluorous phase in contact with an organic phase was only seen with fluoroacrylates that contained larger fluorinated ester groups.

The effects of 1-nitropyrene, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and 7,12-dimethylbenz[a]anthracene on 8-hydroxy-2'-deoxyguanosine levels in the rat mammary gland and modulation by dietary 1,4-phenylenebis(methylene) selenocyanate.

Humans are exposed to 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 1-nitropyrene (1-NP) via several environmental sources and both are known mammary carcinogens in rodents, with the former being more potent (K. El-Bayoumy, Y.-H. Chae, P. Upadhyaya, A. Rivenson, K. Kurtzke, B. Reddy, S.S. Hecht, Comparative tumorigenicity of benzo[a]pyrene, 1-nitropyrene, and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine administered by gavage to female CD rats, Carcinogenesis 16 (1995) 431-434). Following their metabolic activation, both carcinogens are known to bind covalently to DNA. However, it remains to be determined whether these carcinogens can also induce DNA-base oxidation. Our goal was to determine the effects of PhIP and 1-NP on the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG; a marker of oxidative DNA damage) in rat mammary glands and to evaluate the effect of the chemopreventive agent 1,4-phenylenebis(-methylene)selenocyanate (p-XSC) as an inhibitor of such damage. As an established potent mammary carcinogen, the synthetic 7,12-dimethylbenz[a]anthracene (DMBA) was included in this study. Female CD rats were fed a high-fat AIN-76A diet (23.5% corn oil) supplemented with p-XSC (10 ppm as selenium) or unsupplemented control diet for 1 week. At 50 days of age, each rat (12 rats/group) was gavaged with either PhIP (22 mg (100 micromol) per rat) or I-NP (20 mg (80 micromol) per rat) in trioctanoin (0.5 ml), DMBA (5 mg (20 micromol) per rat] in olive oil (0.2 ml), or the corresponding vehicle. Rats were sacrificed 6 and 24 h after carcinogen treatment (six rats per time point). Mammary fat pads were excised and DNA was isolated and enzymatically hydrolyzed. The hydrolysates were analyzed for 8-OHdG using HPLC with EC detection. PhIP significantly increased the levels of 8-OHdG by 83% after 6 h (P < 0.05), but the increase (47%) at the 24 h point was not significant. p-XSC alone had no effect on the levels of 8-OHdG. However, the elevation of 8-OHdG caused by PhIP at 6 h was significantly inhibited by p-XSC to levels similar to those measured in rats treated with the vehicle only (P < 0.05). p-XSC had no effect on PhIP-induced 8-OHdG at 24 h. I -NP had no effect on the levels of 8-OHdG at either time point. Levels of 8-OHdG were increased by 22% 6 h after DMBA administration and, significantly, rose to 84% at 24 h (P < 0.01); at either time point, this elevation was not inhibited by p-XSC. Although the mechanisms remain to be determined, to our knowledge, this is the first report demonstrating that PhIP and DMBA are capable of enhancing 8-OHdG levels in the rat mammary tissue in vivo.

Ozone. The good, the bad, and the ugly.

Sensitive individuals are at risk of adverse health effects from exposure to even modest levels of ozone. Such individuals are likely to develop respiratory symptoms and are more likely to be hospitalized when exposed to ozone at currently accepted levels. A review of scientific documents regarding the health effects of ozone has led the DHHS to agree with the EPA that the primary ambient air standard for ozone should be changed from 0.12 ppm (1-hour average) to 0.08 ppm (8-hour average). Achieving the proposed 0.08 ppm standard should decrease physician visits, hospitalization, and use of respiratory medications. In addition, because very susceptible healthy individuals may experience adverse health effects of the current standard, it is clear that the current standard provides little or no margin of safety, particularly for sensitive individuals. In order to avoid exposure to unhealthy levels of ozone, people should take precautions to minimize exposure from 2:00 to 6:00 pm on days when ozone levels are high. This is especially so for children, adults who are active outdoors, those with respiratory disease such as asthma, and people with unusual susceptibility to ozone.