bluuebunny/crossref_metadata_2025 huggingface dataset:
Supporting Our Junior Faculty
Authors: Good Jessica J. , Keeley Jared W. , Leder Sadie , Afful Stephanie E. , Stiegler-Balfour Jennifer J.
Published: September 2013

The American Psychological Association and its divisions have developed various resources aimed at aiding early career psychologists (ECPs); yet, very little research has been conducted to assess the actual needs of this group. Specifically, research has not identified the needs and concerns of junior faculty engaged in classroom teaching. As members of the Society for the Teaching of Psychology (STP)’s ECP Council, we sought to remedy this by conducting a nationwide online survey of ECPs ( N = 85), asking about the characteristics of their work and their greatest concerns as junior faculty. Results indicated that the top concerns involved finding a balance, both between work and family, and between the three major aspects of an academic position: teaching, research, and service. Participants also reported that prepping classes and fulfilling tenure requirements were major concerns. In addition, we found that participants who were members of the STP reported significantly greater use of STP resources than nonmembers. In this article, we utilize these findings to provide practical suggestions for those attempting to understand and help today’s early career faculty in meeting the many demands of an academic psychologist career.
Experimental and theoretical study of the ignition of timber by an incandescent lamp
Authors: Wang Fengli , He Yaping , Li Pan , Chen Xiao , Zhou Dechuang , Wang Jian
Published: September 2013

In this work, an experimental and theoretical study of the ignition of 20 mm thick paulownia wood exposed to a clear glass envelope incandescent light was performed. The experimental study includes both calibration tests and ignition experiments. Three simple models are established to estimate the incident heat flux in different positions, and the minimum heat flux to achieve ignition, and to correlate the ignition time with distance between the incandescent lamp and the wood sample. Considerable agreement between experimental and theoretical results was obtained in most cases.
Developmental Assets and Ethnic Identity as Predictors of Thriving in Hispanic Adolescents
Authors: Alvarado Melissa , Ricard Richard J.
Published: September 2013

This study examined the confluence of developmental assets, ethnic identity, and acculturative stress in the prediction of thriving among Hispanic adolescents. Thriving is used to encompass youth who are not only doing well now but who are also on the trajectory toward overall success. Study participants included 130 self-reported Hispanic middle and high school students participating in a leadership program specifically geared toward at-risk students. The results indicated that ethnic identity and developmental assets positively predict adolescent thriving. As expected, the correlations between developmental assets scores (context and category) and composite thriving were all significant and positive. Specifically, internal assets and ethnic identity were the main predictors of thriving according to regression analysis. Implications for professionals working with Hispanic youth are discussed.
Factors Affecting Wealth Accumulation in Hispanic Households
Authors: Fontes Angela , Kelly Nicole
Published: September 2013

This research addresses differences between Hispanic ( N = 2,333) and White ( N = 15,521) households in the ownership and allocation of two representative measures of wealth accumulation, stock and homeownership. Using data from the 2008 panel of the Survey of Income and Program Participation, this research estimates a two-stage interaction model to examine differences in both asset ownership and asset allocation decisions. This article established two important findings: (1) results indicate that the negative effects of Hispanic ethnic identity on asset ownership were the result of disadvantaged positions of Hispanic households in the distribution of financial, immigration-related, and demographic characteristics, and (2) once ownership was controlled for, there is no difference in the holdings of stock allocation or home equity between Hispanic and White households.
Acculturation-Related Stress and Mental Health Outcomes Among Three Generations of Hispanic Adolescents
Authors: Cervantes Richard C. , Padilla Amado M. , Napper Lucy E. , Goldbach Jeremy T.
Published: September 2013

Stress associated with acculturation and minority status among Hispanic youth is understudied. Using survey data from the Hispanic Stress Inventory–Adolescent Version (HSI-A), we examined psychosocial stress across eight domains including family economic stress and acculturation-gap stress in a national sample of three generations (first, second, and third or higher) of Hispanic adolescents ( N = 1,263). Research questions addressed generation differences in frequency of stressor events (i.e., discrimination), appraisal of these events, and mental health symptoms. Results indicated that experiences of different categories of stress were significantly related to generation status. The first generation reported more stressors and greater stress appraisal than the third-generation adolescents. Similar levels of discrimination stress were reported by participants regardless of generation. The second-generation participants reported a greater number of Acculturation Gap Stressors than the third generation, and more delinquent and aggressor behaviors than first-generation participants. An acculturation paradox was found with greater stress exposure and stress appraisals in the first-generation youth, but with lower mental health symptoms than later generations. Family integrity and more traditional family values may buffer the negative impact of greater stressor exposure among immigrants and second-generation youth when compared with third-generation adolescents.
The Massachusetts Blood Pressure Study, Part 3. Experimental Reduction of Sodium in Drinking Water: Effects On Blood Pressure
Authors: Calabrese Edward J. , Tuthill Robert W.
Published: September 2013

An experimental bottled water study assessed the effect on blood pressure of lowering Na concentration in the water of some of the high sodium community fourth graders. For three months, trios of children matched by sex, school, and baseline BP each used different water for all cooking and drinking purposes, with BP monitored bi-weekly. Pupils were randomly allocated to the three water conditions: (1) high sodium water bottled from their own community distribution system, (2) low sodium water bottled from the distribution system of the comparison community with sodium added to the level of the high sodium community water and (3) low sodium water bottled from the distribution system of the low sodium community but with no sodium added. The results indicate that BP levels among the girls but not boys on the low sodium water exhibited marked decreases in BP over the test period when compared to the other two groups.
Health Implications of a 5 Mm Hg Increase in Blood Pressure
Authors: Wilkins John R. , Calabrese Edward J.
Published: September 2013

The health implications of a mean increase in blood pressure on the order of 5 mm Hg among young persons are explored primarily from a public health point of view. After an overview of the epidemiologic behavior of human blood pressure is provided, the phenomenon of "tracking" of blood pressure is examined as is the possible relationship between the rate of blood pressure change over time and the initial value. In the last part of the paper, the community benefits of lowering the average blood pressure 5 mm Hg (in terms of number of heart attacks prevented) are estimated under several simplifying assumptions.
A Statistical Model for Species Extrapolation Using Categorical Response Data
Authors: Hertzberg Richard C. , Miller Michael
Published: September 2013

Predictions of human health risk for single chemicals are often based on animal studies and hence require some sort of adjustment for species differences in toxic susceptibility. In the past, either the animal dose has been divided by an uncertainty factor or the dose has been transformed by a mathematical model into a human equivalent dose. A generalization of the allometric model previously used for carcinogens, the so-called "surface area model, " is investigated here for use with graded severity response data for noncarcinogenic systemic toxicity. Statistical methods for estimating one of the model's parameters, the power of body weight, are proposed and tested on simulated and actual toxicity data. Early results indicate reasonable accuracy if data are available for a large number of dose groups.
Methods for Route-To-Route Extrapolation of Dose
Authors: Pepelko William E. , Withey James R.
Published: September 2013

Results of acute toxicity studies for a variety of chemicals have indicated that, in most cases, although the inhalation route was more effective than the IG route, wide variations in toxicity occurred between these two routes. The major factors that may result in variations in toxicity between routes include: (1) differences in absorption efficiency; (2) differences in systemic effects; (3) occurrence of critical toxicological effects at the portal of entry; (4) first-pass effects resulting in inactivation or activation of the chemical agent before it reaches the target organ; and (5) variations in temporal patterns of target organ concentrations.

Extrapolation to determine safe exposure levels during chronic exposure becomes less reliable, not only as information relating to these factors decreases, but also as the quality or length of exposure decreases in the available toxicologic studies. VDC is an example of one of a few chemicals for which both chronic inhalation and oral toxicity data are available, along with detailed pharmacokinetic information. On the basis of the pharmacokinetic data, differences in toxicity between the two routes did not appear to be very likely for this chemical. This conjecture was supported by the results of chronic toxicity studies. Finally, assuming sufficient data and pharmacokinetic parameters are available, this paper presents a useful and practical approach to route extrapolation.
Permissible Concentrations of Chemicals in Air and Water Derived From Rtecs Entries: a "Rash" Chemical Scoring System
Authors: Jones Troyce D. , Walsh Phil J. , Zeighami Elaine A.
Published: September 2013

Many chemicals are of concern to human health, but only a few have epidemiologically derived risk estimates. About 45,000 chemicals are listed in RTECS, most of which have had some testing in subhuman models. RTECS entries range from cellular effects through organoleptic damage to lethality, with many pathological endpoints listed, including mutagenic changes, irritation, teratogenesis, cancer, mortality, etc. However, it is difficult to extend any biological test results to human risk assessments. If the results are extended, the degree of validity is highly uncertain.

This paper describes a logical basis for using the entire complex spectrum of test results to evaluate the overall toxicological potency of a chemical to be assayed ( i.e., an interviewing chemical) and describes how to derive tentative, permissible concentrations in air and water for any particular chemical for which no regulatory guidance exists. This approach has been tested for 16 reference chemicals discussed in NIOSH Criteria Documents, EPA-CAG reports, etc. The evaluations are uncomplicated, but occasionally it is difficult to match RTECS entries for two different chemicals. Difficult compar isons may require some familiarity with experimental design and the toxicological literature.

One important product of this novel approach is that a distribution or array of potency values is obtained for any chemical evaluated. This distribution reflects many uncertainties stemming from low statistical power, experimental design, pharmacological processes, interspecies variability, dose rate, biological effect monitored, route of treatment, etc. The array of relative values for a particular chemical reflects many different biological and physical conditions. The distribution of the array helps to index a composite toxicological profile for many different biological effects resulting from numerous treatment protocols.

To minimize the effect of extreme sensitivity of certain (perhaps novel) biological test models, possible errors in the RTECS database, and possible human pharmacological insensitivity to a particular chemical and/or a particular route of administration, we consider the interquartile range (i.e., the central 50%) of the array of relative potency values between two chemicals being compared as a practical measure of uncertainty. Thus, the range in response derived from variability in relative potency should be useful in addressing the range of response in man as estimated from extrapolations of test data.
Percutaneous Absorption of Anthracene in the Rat: Comparison of in Vivo and in Vitro Results
Authors: Yang Joseph J. , Roy Timothy A. , Mackerer Carl R.
Published: September 2013

The present study was conducted to evaluate the applicability of in vitro percutaneous absorption techniques to estimate in vivo absorption of polynuclear aromatic (PNA) compounds commonly found in mineral oils. The percutaneous absorption of 14C-labeled anthracene, a three-ring PNA, was compared in a six-day in vivo and in vitro experiment with female Sprague-Dawley rats following a single topical dose (9.3 μg/cm2). In vivo absorption was mea sured by the presence of 14C radioactivity in urine, feces and tissues and in vitro absorption by penetration of radioactivity through excised skin into the receptor fluid of Franz-type diffusion cells. Several modifications of standard diffusion cell techniques were used which are known to enhance the absorption of lipophilic compounds. Anthracene was observed to readily penetrate the skin in both experiments and the total amounts absorbed in vivo and in vivo were seen to gradually coalesce over time. Within six days after application, 52.3 and 55.9% of the administered anthracene was absorbed in vivo and in vitro, respectively.
Absence of Hydrocarbon-Induced Nephropathy in Rats Exposed Subchronically To Volatile Hydrocarbon Mixtures Pertinent To Gasoline
Authors: Aranyi Catherine , Oshea William J. , Halder Clive A. , Holdsworth Charles E. , Cockrell Beverly Y.
Published: September 2013

Ninety-day inhalation studies were conducted on 50:50 weight per cent (wt %) mixtures of n-butane:n-pentane and isobutane:isopen tane, respectively, and on a distillation cut boiling below 145° F of a reference unleaded gasoline blend to assess the nephrotoxicity of these volatile mixtures. The mixtures of butanes and pentanes were selected because these four hydrocarbons are the most prevalent components of gasoline vapors encountered under typical occupa tional exposures. The 0-145° F gasoline distillation fraction was tested because it reasonably approximates the composition of gaso line vapors measured under occupational settings. Male and female F-344 rats were exposed to 2 levels of each mixture, 6 hours per day, 5 days per week, for 13 weeks. The target concentrations for the butane:pentane mixtures were 4500 and 1000 parts per million (ppm), while 5200 and 1200 ppm were set for the gasoline distilla tion fraction. An interim sacrifice was conducted after 28 days. The rats were not significantly affected by the exposures, and there was no evidence of hydrocarbon-induced nephropathy in either sex at the termination of each study. However, at the 28-day interim sac rifice period for both butane:pentane mixtures, mild, transient treatment-related but not exposure-related kidney effects were observed in the male rats. These perturbations were absent at the interim sacrifice period for the gasoline distillation fraction.
A Methodology for Assessing Developmental and Reproductive Hazards of Chemicals
Authors: Brown Halina Szejnwald , West Carol Rowan , Bishop Donna R. , Hicks Labelle R.
Published: September 2013

A method to evaluate developmental and reproductive toxicity for a wide variety of chemicals has been developed. The assessment includes all effects on male and female reproductive function as well as effects in the developing embryo or fetus. Effects are evalu ated using primary literature. Studies are classified as adequate, supportive or inadequate. Only adequate studies are used in further assessment. Reproductive and developmental toxicity of each chemical is assessed using both qualitative and quantitative infor mation. Three elements are used to describe developmental toxicity of chemicals: Lowest Observed Effect Level (LOEL), weight-of- evidence classification and a Risk Ratio (RR). For reproductive toxicity only two elements are used, LOEL and weight-of-evidence. LOEL is defined as the lowest dose at which statistically significant effects are found. A risk ratio is calculated using the levels of the chemical producing acute maternal lethalilty (LD50 or LC5o) to the levels producing developmental toxicity in the same animal species and route of administration. The risk ratio is used to indicate the extent to which the developing embryo or fetus is more susceptible than the dam to the toxic effects of a chemical. A toxicity score (A
Mechanisms of Rodent Liver Carcinogenesis
Authors: Michalopoulos George K. , Eckl Peter M. , Cruise Jennifer L. , Novicki Deborra L. , Jirtle Randy L.
Published: September 2013

Stimulation of DNA synthesis by peroxisonte proliferators, including DEHP, should be viewed differently from the stimulation of DNA synthesis by xenobiotic chemicals which stimulate restorative hyperplasia after hepatic necrosis induced by the toxicity of the chemical. The emerging picture of the control mechanisms for hepatocyte proliferation suggests that rather few and distinct factors are involved. The stimulation of DNA synthesis by peroxisome proliferators should be examined in the context of the effects of these factors. Comparisons with other xenobiotics show that induction of DNA synthesis at rates comparable to those of peroxisome proliferators is not sufficient to explain the rates of carcinogenicity associated with peroxisonie proliferators. These considerations lead to the conclusion that although DNA synthesis enhances the incidence of neoplasia, it should not be viewed as a complete carcinogen, nor should it be considered as resulting in initiation at rates that can explain the carcinogenic potency of compounds such as peroxisome proliferators.
Teratogenic Potential of Triphenyl Phosphate in Sprague-Dawley (Spartan) Rats
Authors: Welsh John J. , Collins Thomas F.X. , Whitby Karen E. , Black Thomas N. , Arnold Alphonso
Published: September 2013

Male and female Sprague-Dawley (Spartan) rats were fed dietary levels of 0, 0.25, 0.50, 0.75 or 1.00% triphenyl phosphate (TPP) from 4 weeks post weaning for 91 days, through mating and gesta tion. At these dietary levels, the daily intake of TPP during preg nancy was 0, 166, 341, 516 and 690 mg/kg body weight, respectively. TPP exposure had no toxic effects on mothers or offspring at these dosages. The types of developmental anomalies were similar in both treated and control animals. No significant increases in the incidence of anomalies were seen in the treated groups as compared to control values. TPP was not teratogenic in Sprague-Dawley rats at the levels tested.
Pathologic Effects of Chronic Administration of Hydrochlorothiazide, with and without Sodium Nitrite, to F344 Rats
Authors: Lijinsky William , Reuber Melvin D.
Published: September 2013

The diuretic drug hydrochlorothiazide was administered to 24 male and 24 female F344 rats as a mixture of 0.1% in powdered food. A parallel group of the same size was given 0.1% hydrochlorothiazide plus 0.2% sodium nitrite in the food. A third group received 0.2% sodium nitrite in the food and there was a similar group of untreated controls. The treatments were well tolerated and there was no significant life shortening. A majority of the rats given hydrochlorothiazide, with or without nitrite, developed chronic progressive nephropathy, which was more severe in males than in females. Associated with this were diffuse parathyroid hyperplasia in both groups receiving the drug, also more severe in males than in females, and parallel increases in lesions of the blood vessels (mural thrombosis of the heart and polyarteritis). The few adenomas of the parathyroid and tubular cell adenomas of the kidney in rats ingesting hydrochlorothiazide were not statistically significant.
Comparative Dermal Carcinogenesis of Shale and Petroleum-Derived Distillates
Authors: Clark Charles R. , Walter Mark K. , Ferguson Paul W. , Katchen Mark
Published: September 2013

Ten test materials derived from petroleum or hydrotreated shale oils were applied 3 times/week for up to 105 weeks to the shaved skin of 25 male and 25 female C3H/HeN mice per group. Mineral oil and benzo(a) pyrene (0.15%) were control materials. Clinical observations were recorded during the study. At death, histopathologic examination was conducted on skin, internal organs and any gross lesions. Exposures to some materials were ended midway in the study due to severe irritation. Chronic toxicity of all materials was limited to inflammatory and degenerative skin changes. Significant increases over control incidence of skin tumors (squamous cell carcinoma and fibrosarcoma) occurred with both petroleum and shale-derived naphtha (21%, 50%), Jet A (26%, 28%), JP-4 (26%, 50%), and crude oils (84%, 54%). Severely hydrotreated shale oil and petroleum and shale-derived diesel distillates were not considered tumorigenic. Results indicate that toxicity of comparable petroleum and shale-derived fractions was qualitatively similar and confirm earlier findings that hydrotreating reduces or eliminates carcinogenicity of raw shale oil.
Lack of Effect of Selenium On Induction of Tumors of Esophagus and Bladder in Rats By Two Nitrosamines
Authors: Lijinsky W. , Milner J.A. , Kovatch R.M. , Thomas B.J.
Published: September 2013

The effect of differences in level of dietary selenium on the induction of esophageal and bladder tumors in rats by two nitrosamines was investigated. Groups of 20 female F344 rats were given a synthetic diet containing less than 0.05 ppm Se to which selenium (as sodium selenite) was added at the concentration of 0.35, 0.7, 1.4 and 2.1 ppm selenium. These four groups, plus one without added Se, were treated with 20 ml per rat per day, 5 days a week, of a solution of nitrosomethylcyclohexylamine containing 5 mg/liter. A parallel five groups were treated in the same way with a solution of nitrosomethyl-3-carboxypropylamine in drinking water containing 600 mg per liter, as drinking water. Treatment lasted 28 weeks, at which time some animals had developed tumors. A group of 20 rats fed 0, 1.4 and 2.1 ppm Se was not treated with carcinogen. Rats consuming 1.4 ppm or 2.1 ppm Se gained weight more slowly than other groups. There was no significant difference in survival between the five groups treated with each carcinogen but receiving different dietary levels of selenium. Neither was there any significant difference between groups receiving each carcinogen in the incidence of tumors of the esophagus induced by nitrosomethylcyclohexylamine or of tumors of the urinary bladder induced by nitro somethylcarboxypropylamine. Control rats on the synthetic diets did not survive as well as untreated rats eating regular chow diet. In these conditions there was no effect of dietary selenium levels on the induction of tumors in female rats by the two carcinogenic nitrosamines we used.
Health Effects of the Alkylbenzenes. II. Ylenes
Authors: Low Lawrence K. , Meeks J. Ralph , Mackerer Carl R.
Published: September 2013

The alkylbenzenes are a class of six-membered ring aromatic compounds that have a variety of alkyl groups attached. These chemicals are liquids with relatively low boiling points used primarily as solvents or as starting materials in the synthesis of other chemicals and drugs. They are integral components of gasoline, distillate fuels and other petroleum products and are economically important in the chemical, petroleum, pharmaceutical, polymer, paint and dye industries. Alkylbenzenes such as toluene, the xylenes, ethylbenzene, styrene and cumene are produced and utilized in large quantities and therefore, present the possibility of exposure to humans and to wildlife. Fortunately, the toxicity of alkylbenzenes has been found to be rather low and therefore, the human and environmental risks are probably low. In modern industrial activities, exposures to the alkylbenzenes are minimized by workplace controls or personal protective equipment which meet guidelines for maximum allowable exposure concentrations that have been established for the workplace. Nevertheless, considerable quantities of alkylbenzenes are released to the environment each year through solvent and fuel evaporation, accidental spills and misuse, and considerable toxicological infonnationfor these materials has appeared in the recent literature. This present paper, the second in a series reviewing the potential health effects of alkylbenzenes, covers the toxicology and disposition of the dimethyl-substituted benzenes (the .xylenes) in animals and man.
Carcinogenic Risk Assessment of Complex Mixtures
Authors: Krewski D. , Thorslund T. , Withey J.
Published: September 2013

Although procedures for assessing the carcinogenic risks associated with exposure to individual chemicals are relatively well developed, risk assessment methods for mixtures of chemicals are still in the developmental stage. In this paper, we examine the difficulties in assessing the risks of exposure to complex mixtures, with special reference to the potential for synergistic effects among the compo nents of the mixture. Statistical models for describing the joint action of multiple exposures are reviewed, and their implications for low-dose risk assessment are examined. The potential use of pharmacokinetic models to describe the metabolism of mixtures is also considered. Application of these results in regulating mixtures of carcinogenic substances is illustrated using examples involving multiple contaminants in drinking water and polycyclic aromatic hydrocarbons produced from combustion sources.
Subchronic Toxicity Studies Indicate that Tris(2-Chloroethyl)Phosphate Administration Results in Lesions in the Rat Hippocampus
Authors: Matthews H.B. , Dixon D. , Herr D.W. , Tilson H.
Published: September 2013

Tris(2-chloroethyl)phosphate (TRCP), a flame-retardant plasticizer used in plastics, polymeric foams and synthetic fibers, was studied as part of the National Toxicology Program's class study of phosphate flame-retardants. TRCP was administered at 0, 22, 44, 88, 175 and 350 mg/kg to both sexes of rats and 0, 44, 88, 175, 350 and 700 mg/kg to both sexes of mice in both fourteen day repeat dose and sixteen week subchronic studies. Results of these studies showed that TRCP toxicity in the 14-day studies was limited to modest increases in male rat kidney and female rat liver weights. Little evidence of toxicity was observed in mice in the 14 day studies. Toxicity observed in mice in the sixteen week studies was limited to increased liver weights in both sexes and decreased kidney weights in males. Administration of TRCP to rats for sixteen weeks resulted in increased mortality of both males and females, increased liver and kidney weights and a lesion in the hippocampal region of the brain. The lesion observed in rat brain appeared as loss of the pyramidal neurons of the CA1 region of the hippocampus and was both more common and more severe in female rats. This lesion, which was not observed in mice, is unusual for any chemical and is unique for a trialkyl phosphate such as TRCP. It is speculated that this highly directed toxicity of TRCP might be used as a chemical probe to investigate the role of the hippocampus in behavior and other functions.
Pulmonary Function Study in Female Grinders Exposed to Agate Dust
Authors: Rastogi Subodh K. , Gupta Brahma N. , Mathur Neeraj , Husain Tanveer , Mahendra Prakash N.
Published: September 2013

This paper reports a cross-sectional study of a non-smoking population of silica exposed female workers compared with a group of healthy non-exposed females. The exposed group is divided into cohorts according to the presence or absence of pneumoconiosis in either simple or complex form. The study revealed statistically significant difference in pulmonary function between each of the pneumoconiosis group and the controls and healthy exposed workers. Furthermore, there was statistically significant difference between the values of pulmonary function parameters of the healthy exposed group and the controls. The most important observation of the study is that almost equal decrement of pulmonary function values was observed in the diseased groups and in the healthy exposed group compared to the decrement seen between the latter group and the control group. VC and FVC showed a mean fall of 11.0 and 11.5% in the healthy exposed group as compared to those observed in the unexposed controls (p < 0.01 and p < 0.05) while in the pneumoconiosis group VC and FVC showed 16.9 and 18.2% decrease as compared with the values obtained in the healthy grinders (p < 0.01). Similarly FEV1 showed almost same decrease in the healthy (17.9%) and diseased (20.7%) exposed groups (p < 0.001). However, FEV0.75 and MVV parameters showed greater decrement (25.4 and 33.7%) in the pneumoconiosis group as compared to 15.7 and 18.5% observed in the healthy exposed workers. The important observation made in this study is that potential pulmonary debilitation may occur in pneumoconiosis before, or in the absence of, any radiologic findings.
Asbestos Disease at Low Exposure after Long Residence Time in Amphibole Miners
Authors: Sluis-Cremer Gerhard K.
Published: September 2013

Short reports of several studies carried out in South Africa which have a bearing on the health effects of low exposures to asbestos are presented. It is stressed that the findings refer solely to amphibole asbestos. Average fiber exposure of 1 or less or a cumulative expo sure of > 2-5 fibers/ml years is associated with the development of asbestosis increasing in frequency with residence time.
Effects of Repeated Intermittent Exposures to Nitrous Oxide on Central Neurotransmitters and Hepatic Methionine Synthetase Activity in Cd-1 Mice
Authors: Abdul-Kareem Hind S. , Sharma Raghubir P. , Drown David B.
Published: September 2013

The central neurotransmitters and hepatic methionine synthetase (MS) appear to play an important role in mediating the side effects associated with N2O exposure. Male CD-1 mice were exposed to 0, 50, 500, and 5,000 ppm of N2O 6 hr per day, 5 days a week for 2 or 13 weeks. One day after the last day of exposure, the animals were decapitated and steady state concentrations of norepinephrine (NE), dopamine (DA), serotonin (5-HT), 3-methoxy-4-hydroxy- mandelic acid (VMA), 3-methoxy-4-hydroxyphenyl glycol (MOPEG), dihydroxyphenylacetic acid (DOPAC), and 5-hydrox yindoleacetic acid (5-HIAA) were determined in six discreet brain regions using electrochemical high-performance liquid chromatogra phy. Hepatic MS activity was measured using a newly developed non-isotopic method. After a 2-week exposure to 5,000 ppm N2O, levels of NE and DA in some brain regions were significantly increased and were accompanied by significant decreases in the levels of their major metabolites. Serotonin levels were significantly decreased in certain brain regions. After the 13-week exposure to
An Assessment and Quantitative Uncertainty Analysis of the Health Risks to Workers Exposed to Chromium Contaminated Soils
Authors: Paustenbach Dennis J. , Meyer Deborah M. , Sheehan Patrick J. , Lau Virginia
Published: September 2013

Paustenbach, Dennis J., Deborah M. Meyer, Patrick J. Shee han, and Virginia Lau (1991). An assessment and quantitative uncertainty analysis of the health risks to workers exposed to chromium contaminated soils. Toxicol. Industrial Health.

Millions of tons of chromite-ore processing residue have been used as fill in various locations in Northern New Jersey and else where in the United States. The primary toxicants in the residue are trivalent chromium [ Cr(III)] and hexavalent chromium [ Cr(VI)]. The hazard posed by Cr(III) is negligible due to its low acute and chronic toxicity. In contrast, Cr(VI) is considered a inhalation human carcinogen at high concentrations. Approxi mately 40 commercial and industrial properties in Northern New Jersey have been identified as containing chromite ore processing residue in the soil. One site, a partially-paved trucking terminal, was evaluated in this assessment. The arithmetic mean and geo metric mean concentrations of total chromium in soil were 977 and 359 mg/kg, respectively. The data were log-normal distrib uted. The arithmetic mean and geometric mean concentrations of Cr(VI) in surface soil were 37.6 and 3.1 mg/kg, respectively. The data could not be fit to a standard distribution, likely due to the large number of samples with concentrations below the method detection limit (65%). Dose was calculated for each exposure route using a Monte Carlo statistical simulation.
Repeated-Dose Gavage Studies on Polychlorotrifluoroethylene Acids
Authors: Kinkead Edwin R. , Bunger Susan K. , Wolfe Robin E. , Flemming Carlyle D. , Whitmire Richard E. , Wall Henry G.
Published: September 2013

C8 polychlorotrifluoroethylene (pCTFE) oligomers accumulate preferentially in the liver during long-term oral exposure and appear to be more hepatotoxic than C6 oligomers. A repeated-dose gavage study was initiated to determine the relative contributions of the corresponding C6 (trimer) and C8 (tetramer) acid metabolites to the toxicity of pCTFE in the male Fischer 344 rat. Test animals were dosed once per week for various time periods up to one year. A depression (p < 0.05) in mean body weight occurred in the highest dose tetramer acid (2.16 mg/kg) group. An increase in hepatic peroxisomal β-oxidation activity was found in the 2.16 mg pCTFE tetramer acid/kg dose group at the 3-, 6-, and 9-month sacrifice periods. An increase in relative liver weight was seen at all sacrifice periods in this dose group. Hepatocellular cytomegaly was a common finding in the higher dose tetramer acid groups but not in the trimer-treated rat groups.
Environmental Impact Assessment as a Tool for Risk Management
Authors: Ratanachai Chatchai
Published: September 2013

Environmental Impact Assessment is essentially a process comprising four elements: identification, prediction, evaluation, and monitoring. Properly conducted EIA studies can identify linkages between injurious events and/or activities and their damaging consequences. This aids in making the risk management decision.

This paper discusses how EIA can be used as a tool for risk managemnet. Each element of EIA, as well as available risk management options, is discussed. As a case example, the paper reviews EIA guidelines/procedures in Thailand and identify weakness and strength in capabilities to identify the sensitive areas where risk should be effectively controlled.
The Effect of Aluminum On Conditioned Avoidance Response (Car) in Mice
Authors: Yen-Koo Helen C.
Published: September 2013

Aluminum is used in medical products and some parenteral products (Vaccines) contain aluminum. In a study of neurotoxicity of aluminum in mice, four groups of CD 1 mice (5 males and 5 females per dose level) were treated as follows: group one drank 1.0% of aluminum (as AlCl3) during the weaning period from day 1 to 8 weeks of age; group two drank AlCl3 from 1 month to 4 months of age; group three mice (1 month old) were injected i.p. with 10, 30 and 100 mg of aluminum /kg/day for two days; group four mice (1 month old) were injected s.c. with 3, 10, and 30 mg of aluminum/kg/day for 2 days. Controls received the vehicle only. All mice were trained for CAR five times at 2 months of age. The CAR of mice that ingested AlCl3 during the weaning period to 8 weeks of age was lowered by 26% compared to the control group, which achieved 46% of CAR after five training sessions. Also, the retention of CAR was reduced to 30% whereas that of the control group remained at the same level after 1 month. CAR values of group two did not differ from those of its control. CAR of group three (at 30 mg/ kg i.p.) was 36% lower than controls. CAR of s.c. group four (3, 10, and 30 mg/kg) was lowered to 16%-28% of the control; CAR retention was reduced to 18%. Therefore, the oral ingestion of aluminum induced neurotoxicity in mice which may be seen only at an early age, but injection of aluminum can cause neurotoxicity at any age.
Man-Made Mineral Fibers and Lung Cancer: an Hypothesis
Authors: Pezerat Henri , Guignard Joëlle , Cherrie John W.
Published: September 2013

Epidemiological data have revealed significant excesses of lung cancer among workers exposed to some types of man-made mineral fibers (MMMF), but inhalation experiments performed on rats have failed to reveal the origin of these excesses. Some of these materials, however, are able, in aqueous media, to exhibit surface oxidizing properties after reduction of oxygen by a radical pathway. Tests have been carried out with 12 MMMF samples collected from various sources without prior knowledge of their origin, to determine their oxidizing surface activity in relation to their divalent iron content. Some of these fibers were obtained from factories included in an epidermiological investigation. Only fibers coming from plants where excesses of lung cancer were observed are classified as active in an oxidative process and, consequently, probably toxic in biological media by an oxidative stress mechanism. We therefore propose an hypothesis of a causal relationship between these oxidizing properties and the ability of the materials to induce lung cancer.
On Reference Dose (RFD) and Its Underlying Toxicity Data Base
Authors: Dourson Michael L. , Knauf Linda A. , Swartout Jeffrey C.
Published: September 2013

The toxicity data of pesticides were summarized and compared amongst different animal species and types of bioassays. These comparisons showed the expected inter-species and inter-bioassay variability. After quantitative and statistical analysis of these data, it was concluded that, on the average, a 2-year dog bioassay detected toxic responses at similar doses as a 2-year rat study, and that both of these bioassays detected toxic responses at lower doses than either a rat 2-generation bioassay, a rat developmental toxicity study, or a 2-year mouse bioassay. Although these chronic dog and rat bioassays were found to detect toxic responses at lower doses than the other studies listed, this analysis does not reflect the seriousness of the effects that were compared. Within the confines of this analysis, then, it appears that a 2-year dog and rat study, reproductive and developmental bioassays are a sufficient data base on which to estimate high confidence Reference Doses (RfDs), and furthermore, that an additional uncertainty factor is needed to estimate RfDs to account for this inter-species and inter-bioassay variability when fewer than this number of bioassays are available.
N-Methyl-N'-Nitroguanidine: Irritation, Sensitization, and Acute Oral Toxicity, Genotoxicity, and Methods for Analysis in Biological Samples
Authors: Kinkead E.R. , Wolfe R.E. , Salins S.A. , Godin C.S. , Lu P.P. , Ketcha M.M. , Thilagar A. , Brashear W.T.
Published: September 2013

Currently. N-methyl-N'-nitroguanidine (MNG) is being considered by the U.S. Air Force Armament Laboratory for use in explosive formulations. A mammalian toxicity profile has been performed which includes the analysis of chemical impurities and an assessment of the potential for the metabolism of MNG to 1-methyl-3-nitro-1-nitrosoguanidine (MNNG). Potential in situ gastric conversion of MNG to MNNG is a toxicological concern because MNNG is both mutagenic and carcinogenic. The compound was also evaluated in several bioassays to assess its potential genotoxic activity. The acute oral toxicity was determined in male and female Fischer 344 rats administered a single dose of MNG in corn oil. The maximum suspension of MNG that could be delivered, 1 mg MNG/kg body weight, produced no signs of toxic stress during the 14-day observation period. The primary eye and skin irritation potential of MNG was determined in female New Zealand white rabbits using the Draize technique. MNG produced no irritation to intact skin but did produce mild conjunctival irritation. The response of a single guinea pig to the dermal sensitization evaluation indicated that MNG is a weak sensitizer. The results of three genetic tests indicated that MNG does not interact with genetic material. Gastric contents and feces from treated animals showed no evidence of conversion of MNG to MNNG.
Oxisterol Determination in Selected Coffees
Authors: Turchetto Edoardo , Lercker Giovanni , Bortolomeazzi Renzo
Published: September 2013

The main aim of green-coffee processing techniques, such as decqffeination and roasting, is always to maintain a very high level of quality in taste and flavor, the beverage's most important cliaracteristics to consumers. Oxidative alterations of coffee lipids, which can occur in roasting, exert a very marked influence on these quality traits. Determining the extent of oxidation thus can provide an indication of the product's potential shelf-life and reveal traces of any newly-formed oxidative products that might prove nutritionally unsafe.

Yet, while much attention has recently been focused on certain by-products induced by cholesterol oxidation and their proven toxicity as risk factors in atherosclerosis and cancer, oxidated phytosterols have largely gone unnoticed, being considered along with β-sitosterol as not very dangerous in that neither is absorbed by the intestinal tract. The present study investigates the substances derived from phytosterol oxidation (oxisterols) in samples of regular and decaffeinated commercial coffees. The findings show that oxisterols were absent in some samples and that the traces of oxidate phytosterols detected in others were well below the threshold considered as toxicologically active.
Purification and Characterization of Hepatic P-450Iie1 from Acetone-Treated Mice
Authors: Longo Vincenzo , Menicagli Silvia , Minks Michael , Santucci Annalisa , Gervasi Pier Giovanni
Published: September 2013

A new cytochrome P-450 isozyme (Mr = 52,000) was purified to apparent electrophoretic homogeneity from hepatic microsomes of mice treated with acetone and its biochemical, spectral, and immunological properties characterized. Several criteria indicated that the purified cytochrome was distinct from the known mouse P-450 isozymes. The absolute spectrum of its oxidized form indicated that it was in the high spin state. In a reconstituted system, it showed low catalytic activities towards 7-ethoxycoumarin, aminopyrine, and coumarin, whereas it catalyzed the oxidation of aniline, acetone, dimelhylnitrosoamine with high turnover number. The mouse enzyme was immunoreactive with polyclonal antibodies against rat P-45011E1 and exhibited an NH2-terminal aminoacid sequence with a high homology to that of rat-P-450IIEI. Based upon the above catalytic, spectral, immunological and structural properties, the purified mouse P-450 appears to be the ortholog of previously described P-450IIE1 (s) of other species.
Toluene Diisocyanate: an Assessment of Carcinogenic Risk Following Oral and Inhalation Exposure
Authors: Doe J.E. , Hoffmann H.D.
Published: September 2013

Although respiratory sensitization and pulmonary irritation have been the subject of particular studies with toluene diisocyanate (TDI), in recent years the potential carcinogenicity of TDI has been a reason for concern and speculation. This has arisen from the expectation that following exposure to TDI the chemical would hydrolyze at aqueous tissue surfaces to give rise to toluene diamine (TDA), a mutagen and rodent carcinogen. The chemistry of TDI suggests that the reaction with biological NH2 groups such as those on proteins, and polymerization to oligoureas, will compete with the hydrolysis reaction. This has been shown with results of in vitro studies where conjugation to protein occurs without detectable formation of TDA when protein solutions in saline are exposed to TDI vapor. Lower pH levels leading to high protonation of biological NH2 groups facilitate hydrolysis of TDI to TDA and subsequent formation of polyureas. These observations are consistent with comparative toxicokinetic studies in rats, which demonstrate significant levels of TDA following oral dosing with TDI - due to the acidic environment in the stomach - but not after inhalation. These results provide an explanation for the tumors observed in rodents after oral dosing of TDI in com oil, but not after inhalation. Inhalation is the relevant route of human exposure for TDI and the toxicokinetics of TDI exposure at occupational exposure limits have been studied. These data provide a means by which quantitative estimates of the risk of carcinogenicity possibly resulting from the intermediate formation of TDA during TDI exposure can be obtained. Several calculations have been made, all
Occupational Exposure To Nor-Nitrogen Mustard: Chemical and Biological Monitoring
Authors: Thulin Hans , Sundberg Eva , Hansson Kerstin , Cole Jane , Hartley-Asp Beryl
Published: September 2013

Nor-nitrogen mustard is an alkylating agent used in kilogram quantities in the production of various cytostatics. It has been shown to be mutagenic in vitro, and therefore must be regarded as a health hazard. We have studied the environment and blood of a small group of individuals working with nor- nitrogen mustard. New chemical methods for measuring surface contamination were used to make comparisons with ambient air levels of nor-nitrogen mustard. Surprisingly high levels of surface contamination were found even after decontamination, which has led to new decontamination routines and the establishment of wipe test limits of 0.5 μg nor-nitrogen mustard/dm 2. The wipe test has proved effective in following the day-to-day routine handling of nor- nitrogen mustard. Blood samples were taken before, during, and after production runs and analyzed for the frequency of chromosome aberrations (CAs), sister chromatid exchanges (SCEs), and somatic (HPRT) mutations. No significant differences in chromosome aberrations, SCEs, or somatic mutations were found in the peripheral blood from production workers before, during, or after handling of nor-nitrogen mustard. Nor was any difference found between the production workers and a local control group. However, the local controls' chromosome and HPRT frequencies appeared to be somewhat high, demonstrating the problems involved in these types of studies, in which the group sizes are small.
Tamoxifen — Breast Cancer Preventive or Human Carcinogen?
Authors: Clute Eve
Published: September 2013

Much has been written on both sides of the debate over the safety of tamoxifen. This paper discusses the toxicity of this chemical and the latest findings supporting the end of tamoxifen trials.
Rapid Assay of Cytotoxicity Using Tetramitus Flagellates
Authors: Jaffe Robert L.
Published: September 2013

A simple test for measuring cytotoxic agents has been developed using the flagellate phenotype of Tetramitus rostratus. The test measures dose-dependent inhibition of cell division by individual agents such as 4-nitroquinoline-N-oxide and other mutagens. Dose-response data are given also for mixtures including coal tar pitch condensate, centrifuged particles obtained from tap water, and water concentrates prepared with XAD-2 resin.

Because Tetramitus flagellates have a gullet and are particle-feeders, the assay allows for cytotoxic measurements of whole particles without prior extraction or solvent substitution procedures. The cytotoxic activities observed may reflect genotoxic activity, since all chemicals that produced a positive response are genotoxic in other test systems.