Search

Two complexes, PbCl 2 mbit and Pb(NCS) 2 mbit (mbit=1,1′-methylenebis(3-methyl-2)3 H )-imidazolethione)) have been synthesized and characterized. A single crystal X-ray study of PbCl 2 mbit revealed a unique cross-linked polymeric structure composed of very distorted PbCl 4 S 2 octahedra sharing common edges through long PbCl bridges. The bridging pairs of Cl atoms are displaced cis to each other in the coordination sphere of lead thus creating twisted polymeric PbCI strands running along the c axis. In the direction of the b axis, the strands are further linked by mbit ligands acting as bridges between neighboring twisted strands created by the lead chloride bonds. This is the first instance where mbit is shown to act a bridging ligand. There is no clear evidence for the lone pair of electrons through systematic distortions in the lead coordination sphere. A high melting point of 259–261 °C is consistent with the polymeric structure. Cell parameters are as follows for PbCl 2 mbit: space group Pbca, a =8.699(3), b =17.164(4), c =20.469(6) A, Z =8, V =3056.2 A 3 , D c =2.254 g/cm 3 , D o =2.23 g/cm 3 (λ=0.71073 A). R =0.047. Pb(NCS) 2 mbit complex was also synthesized and characterized, but crystals suitable for X-ray study were not obtained. IR stretching frequencies of the SCN group fall in the ranges observed for this ligand bonding only through N and no evidence for S bonding. The relatively high melting point (254–256 °C) gives evidence for a polymeric structure the details of which remain unknown.

After showing that india (In2O3) resisted high-temperature reaction with SO3/Na2SO4 and vanadate melts, we prepared india-stabilized zirconia (ISZ) by a proprietary sol–gel process, and tested the material for corrosion resistance to 700–900°C molten vanadates. ISZ was superior to yttria-stabilized zirconia (YSZ) in vanadate resistance at 700°C, and essentially equivalent at 900°C. Certain differences were observed between the vanadate-induced corrosion/destabilization of ISZ and that of YSZ.

The complex, Pb(NCS) 2 (dmit) 2 , has been previously reported (dmit=1,3-dimethyl-2(3 H )-imidazolethione). A new complex, Cd(NCS) 2 (dmit) 2 , has also been synthesized and characterized. Single crystal X-ray structural studies were completed for both complexes. Cell parameters for [Pb(NCS) 2 (dmit) 2 ]: space group C 2/ c , a =11.118(2), b =14.121(4), c =12.970(3) A, β=108.29(2)°, Z =4, V =1933.4 A 3 , D c =1.895 g/cm 3 , D 0 =1.93 g/cm 3 (λ=0.71073 A), R =0.030; [Cd(NCS) 2 (dmit) 2 ]: space group C2 / c , a =10.911(2), b =14.172(2), c =12.471(2) A, β=107.54(1)°, Z =4, V =1838.7 A 3 , D c =1.752 g/cm 3 , D 0 =1.75 g/cm 3 (λ=0.71073 A), R =0.031. Both complexes are isostructural polymers comprised of zigzag chains of MS 4 N 2 distorted octahedra sharing common edges through almost perfectly linear bridging SCN groups displaced cis to each other relative to the central metal atom. Thiourea ligands are displaced trans to each other. Comparative bond distances show the formulation of these complexes to be more accurately stated as M(NCS) 2 (dmit) 2 . There is no clear evidence for the lone pair of electrons through systematic distortions in the lead structure although there are greater observed deviations from 90° in the local site symmetry about Pb than about Cd.

Samples of the surficial 17 cm of the plot in continuous corn production since 1876 and without fertility treatment and the adjacent plot, also planted annually to corn but receiving rock and super P among other fertility amendments, were studied. Average uranium (U) content in the untreated corn plot was 3.04 mg/kg, and there was no change between 1904 and 1985. Average U in the P‐treated plot was 3.78 mg/kg and more variable than the untreated plot. Uranium did not increase with addition of 17.6 t/ha of rock P between 1904 and 1919; U increases in 1955 and 1967 may be attributable to limestone applications and in both cases U content declined rapidly with time. From 1923 to 1985 the average annual loss of phosphorus was 1.8 mg/kg from the P‐treated plot that received rock P between 1904 and 1919 and then super P after 1966. This rate of P loss from 1923 to 1985 in the treated plot is not significantly different than that in the untreated plot (1.9 mg/kg). It is speculated that P has eluviated a...

The major Canadian disasters from the 1500s to date are identified by cause and type. General disaster criteria are defined. Twenty or more deaths occurring at one time is the primary criterion. The other principal criterion is to include events which have occurred within Canada and offshore inside the 200 mile economic zone. Events such as wars, epidemics and battles between natives and European settlers during colonization have been excluded. These criteria limit the events which are discussed to a manageable number. The results of an expanded literature search are presented and a brief description of some of the disasters is given. An historical perspective is discussed with a view to illustrating the disasters which were common in early Canadian history, and those which have occurred in modern times. Conclusions are drawn as to which types of natural and man-made disasters are likely to occur in Canada in the future.

Objective—To evaluate efficacy of monthly administration of selamectin and fipronil against Ctenocephalides felis in cats. Design—Randomized controlled trial. Animals—36 healthy cats. Procedure—Cats known to be free of fleas were infested with 100 unfed adult fleas on days –28 and –21. On days 0, 30, 60, 90, and 120, sixteen cats (8 pairs/treatment group) were treated by topical administration of selamectin (6 mg/kg [2.7 mg/lb] of body weight) or fipronil (7.5 mg/kg [3.4 mg/lb]). Four control cats (2 pairs) were not treated. On day –6 and every 2 weeks after initial treatment, comb counts were performed to detect fleas. Flea counts were recorded, and fleas (≤ 50) that had been removed were replaced onto the cat. On day 89, fleas were not replaced. On day 91 and every 7 days until the end of the study (day 150), cats were challenged with 20 adult fleas. Flea counts were compared between and within treatments. Results—14 days after treatment, geometric mean flea counts were reduced by 71.2% by fipronil treatment and 35.3% by selamectin treatment. Both treatments resulted in 97 to 98% reduction in flea counts on day 29 and 99.8 to 100% reduction from day 44 to the end of the study. Conclusions and Clinical Relevance—Selamectin is as effective as fipronil in treating infestation in cats housed for 3 months in a flea-infested environment under conditions known to support the flea life cycle and in protecting against subsequent weekly challenges with C felis for an additional 2 months. (J Am Vet Med Assoc 2000;217:1666–1668)

Posterior shoulder dislocation is a relatively uncommon event, with an incidence of 1% to 4% of all shoulder dislocations. Because of the infrequency of this condition, the diagnosis is often missed, with significant consequences to the patient. Injury in the athlete is usually from a direct blow or fall onto an outstretched arm. After such an injury, symptoms may be confused with a shoulder contusion or rotator cuff injury. Significant complications such as chronic posterior dislocation and degenerative disease of the shoulder can occur if the diagnosis is missed. A careful history and physical examination, complete radiographic evaluation, and a high level of suspicion are required to identify posterior shoulder dislocation. Treatment consists of prompt closed reduction, or operative repair if this is unsuccessful.

This research was conducted to examine the inherent properties of yogurt contaminated with staphylococcal enterotoxin B (SEB). Two types of yogurts were produced for this study. Type I yogurts were produced by adding SEB at the start of yogurt production, and type II yogurts were produced by adding SEB after the milk base had been boiled. Biochemical characteristics inherent to yogurt, including pH, lactic acid and acetaldehyde concentrations, were analyzed weekly for each batch beginning at a time just after production and throughout a storage period of at least 4 weeks. The presence of toxin during yogurt production did not result in any significant biochemical or physical changes in yogurt. However, we were unable to detect SEB toxin in type I yogurt using a commercially available enzyme-linked immunosorbent assay (ELISA). In contrast, SEB was easily detectable by our ELISA in type II yogurt samples. Higher levels of SEB were recovered from type II yogurt that had been stored for 1 week than from type II yogurt that had been stored for any other length of time. These results indicate that the biochemical characteristics of yogurt did not change significantly (relative to control yogurt) in the presence of either thermally processed SEB or native SEB. However, the ability to detect SEB by ELISA was dependent on whether the toxin had been processed.

OBJECTIVES. To evaluate trends in children's blood lead levels and the extent of blood lead testing of children at risk for lead poisoning from national surveys conducted during a 16-year period in the United States. METHODS. Data for children aged 1 to 5 years from the National Health and Nutrition Examination Survey III Phase I, 1988–1991, and Phase II, 1991–1994 were compared to data from the survey period 1999–2004. RESULTS. The prevalence of elevated blood lead levels, ≥10 μg/dL, among children decreased from 8.6% in 1988–1991 to 1.4% in 1999–2004, which is an 84% decline. From 1988–1991 and 1999–2004, children's geometric mean blood lead levels declined in non-Hispanic black (5.2–2.8 μg/dL), Mexican American (3.9–1.9 μg/dL), and non-Hispanic white children (3.1 μg/dL to 1.7 μg/dL). However, levels continue to be highest among non-Hispanic black children relative to Mexican American and non-Hispanic white children. Blood lead levels were distributed as follows: 14.0% were CONCLUSIONS. Children's blood lead levels continue to decline in the United States, even in historically high-risk groups for lead poisoning. To maintain progress made and eliminate remaining disparities, efforts must continue to test children at high risk for lead poisoning, and identify and control sources of lead. Coordinated prevention strategies at national, state, and local levels will help achieve the goal of elimination of elevated blood lead levels.

We describe the distribution and demographic characteristics of total blood Hg levels in the U.S. general population among persons ages 1 year and older who participated in the 2003-2006 National Health and Nutrition Examination Survey (NHANES). We also describe trends in the total blood Hg of children ages 1-5 (n=3456) and females ages 16-49 during 1999-2006 (n=7245). In the combined 2003-2006 survey periods, the geometric means for non-Hispanic blacks, 0.853microg/L (95% confidence interval [CI], 0.766-0.950microg/L), and non-Hispanic whites, 0.833microg/L (95% CI, 0.752-0.922microg/L), were higher than the geometric mean for Mexican Americans, 0.580microg/L (95% CI, 0.522-0.645microg/L). Also in 2003-2006, regression analysis of log total blood Hg with age, race/ethnicity and gender showed that total blood Hg levels in the population exhibited a quadratic increase with age (p0.0001), peaking at ages 50-59 in non-Hispanic blacks and whites, at ages 40-49 in Mexican Americans, and then declining at older ages. Over the four survey periods (1999-2006), regression analysis showed that total blood Hg levels increased slightly for non-Hispanic white children and decreased slightly for non-Hispanic black and Mexican American children. Over the same four survey periods, female children had slightly higher total blood Hg levels than males (0.356 vs. 0.313microg/L, p=0.0050) and total blood Hg levels in non-Hispanic black women aged 16-49 years were significantly higher than in non-Hispanic white women (1.081 vs. 0.850microg/L, p0.0001) and in Mexican American women (1.081 vs. 0.70microg/L, p0.0001).

The study examined the effects of endotracheal suction with and without saline instillation on neonates with respiratory distress. In a completely counterbalanced factorial-within-subjects design, 27 intubated neonates were randomly assigned to two orders of presentation of treatment conditions. Heart rate and blood pressure were continuously recorded throughout both treatment conditions. The ratio of arterial oxygen tension to alveolar oxygen tension was used to assess oxygenation. Results indicated that clinically stable newborns tolerated instillations of 0.25-0.5 ml. The suctioning protocol used in this study minimized changes in infants' heart rates and blood pressures.

Two alpha-D-glucans, produced from amylopectin by an oral isolate Streptococcus sanguis 1 MC 204, were shown to contain both (1----4) and (1----6) linkages. The first alpha-D-glucan (amyloglucan) was adherent and highly insoluble, and methylation analysis, i.r. spectroscopy, and enzymic analyses showed it to be similar to amylopectin but less branched with longer interior and exterior chains. The second polymer was a non-adherent soluble alpha-D-glucan that was similar to amyloglucan but with long exterior chains. These alpha-D-glucans were not synthesised de novo, but were the products of the modification of amylopectin.

A series of group 4 metallocenes possessing chiral ligand environments have been characterized and their structures are compared with their propylene polymerizations. Isotactic, syndiotactic, hemiisotactic, and atactic polypropylenes are produced selectively with chiral monoalkyl metallocene cations paired with perfluorotetraphenyl borate; analogous to the results obtained using methylaluminoxane as a cocatalyst. The relative catalyst stereospecificities suggest specific π-face selectivities and nonbonded contacts. Trends with solvents, temperatures, and catalyst structures are consistent with contact ion pairing for iPr[CpFlu]Zr-P(+) in liquid propylene. The specificities of differently structured metallocenes imply chain-migratory monomer addition reactions.

A potential problem exists with the certification of Class II, Type A, biological safety cabinets using the standard method for deriving cabinet intake velocity. It has been found that the cabinet air flow balance is affected by low ceiling height over the cabinet exhaust opening. Two different Class II, Type A, cabinets and two air flow measuring methods were compared as a false ceiling apparatus was positioned from 5.2 to 35.6 cm (2–14 in.) above the cabinet exhaust opening. The results showed that a ceiling height as low as 5.2 cm (2 in.) above the exhaust plenum had no effect on actual cabinet air flow. Results also indicated two measuring methods yielded different results throughout the range of ceiling heights. Both measuring methods demonstrated a strong negative correlation (-0.9) for derived cabinet intake air velocity as a function of increased ceiling height. The precisely determined, yet inaccurate, operational setpoint (with the low ceiling in place) versus the actual operational set...

Full-unit transfusions of RBC enzymatically converted from group B to group O by treatment with alpha-galactosidase (ECO RBC) to group O and A normal healthy individuals exhibit excellent in vivo survival times (24-hour survival 95.1% +/- 2.3%, T50 36.9 +/- 4.6 days). These results confirm our earlier findings describing ECO RBC in vitro viability and normal in vivo survival time after small-volume infusions. No significant increase in pretransfusion anti-B titer or score is observed in either group O or A subjects provided that sufficient enzyme is used to treat the cells: Cells transfused to group O recipients require higher levels of enzyme (185 to 200 U/mL RBC) than those infused to group A (90 U/mL RBC). Two separate single-unit transfusions of ECO RBC to one group O recipient (4.5 months apart) also survived normally (24-hour survival 96% and 92%, T50 40 and 36 days) and did not increase preexisting anti-B levels in this subject. ECO RBC were not agglutinated or lysed by recipient sera before or after transfusion. Similarly, no antibody development to the alpha- galactosidase used in cell treatment (and washed from the product before transfusion) could be detected in any subject. The sustained increase in hemoglobin levels after transfusion of ECO RBC suggests that this product will be useful in treatment of acute and chronic anemia.

We compared the iron status between children 11 to 33 months old with confirmed blood lead levels of 20 to 44 microg/dL and demographically similar children with blood lead levels of10 microg/dL. There were no differences. Laboratory investigation or empirical treatment for iron deficiency is not justified on the basis of moderately elevated blood lead levels alone.

With funding from The Robert Wood Johnson Foundation's Generalist Physician Initiative, the Pennsylvania State University College of Medicine created a community-based primary care clerkship in general pediatrics, general internal medicine, and family and community medicine, in which third-year students spend a month in a small town, rural area, or urban underserved medical community. In addition to linking students with preceptors who would teach the clinical skills essential to primary care practice, the medical school set out to teach and to evaluate knowledge, attitudes, and behaviors unique to primary care. This paper describes the three-part teaching tool/evaluation developed to address (1) a student's recognition of the characteristics of primary care (learning objectives assignment), (2) a student's ability to appreciate the multiple nonmedical factors influencing a patient's health and experience of illness (family project), and (3) a student's ability to solve clinical problems (clinical reasoning examination). The authors describe how these evaluation methods are linked with the clerkship's goals and objectives and how they yield a richer portrait of the student's performance than the traditional preceptor's evaluation alone can provide. They also discuss the relationship between students' performances on the primary care clerkship and their performances in other clinical clerkships. Similar clinical experiences in primary care should focus on features unique to primary care medicine in both teaching and evaluation.

Multilocus variable number tandem repeat analysis (MLVA) has recently emerged as a genotyping method that is both robust and highly discriminatory for the differentiation of Mycobacterium tuberculosis complex (MTBC) strains, including Mycobacterium bovis. However, MLVA assessment of M. bovis isolates recovered from animals in North America has been limited. Using an epidemiologically diverse set of 41 North American M. bovis animal isolates, MLVA, based on 27 published variable number tandem repeat (VNTR) loci, was evaluated. Nineteen loci displayed polymorphism, which resulted in differentiation of 21 unique MLVA genotypes. A subset of 6 loci differentiated the isolates into 14 genetically related groups that displayed remarkable concordance with the epidemiological data gathered via traditional trace-back methods. In most cases, MLVA exhibited greater resolution than spoligotyping, which differentiated the isolates into 11 groups. MLVA genotyping of M. bovis shows great potential as a molecular typing tool for characterizing the epidemiology of M. bovis animal infections in North America. However, the greatest resolution was achieved by using a combination of both MLVA and spoligotyping.

A robust analytical method has been developed and validated by use of high-performance liquid chromatography inductively coupled plasma mass spectrometry with Dynamic Reaction Cell (DRC) technology that separates seven arsenic (As) species in human urine: arsenobetaine (AB), arsenocholine, trimethylarsine oxide (TMAO), arsenate (As(V)), arsenite (As(III)), monomethylarsonate, and dimethylarsinate. A polymeric anion-exchange (Hamilton PRP X-100) column was used for separation of the species that were detected at m/z 75 by ICP-DRC-MS (PerkinElmer SCIEX ELAN DRCII) using 10% hydrogen-90% argon as the DRC gas. The internal standard (As) is added postcolumn via an external injector with a sample loop. All analyte peaks were baseline-separated except AB and TMAO. Analytical method limits of detection for the various species ranged from 0.4 to 1.7 microg L(-1) as elemental As. As(III) conversion to As(V) was avoided by adjusting the urine sample to

To provide levels of total and speciated urinary arsenic in a representative sample of the US population.For the first time, total arsenic and seven inorganic and organic arsenic species were measured in the urine of participants (n=2557) for the 2003-2004 National Health and Nutrition Examination Survey (NHANES). Data were compiled as geometric means and selected percentiles of urinary arsenic concentrations (microg/l) and creatinine-corrected urinary arsenic (microg/g creatinine) for total arsenic, dimethylarsinic acid, arsenobetaine, and a sum of the inorganic related species.Arsenic acid, arsenous acid, arsenocholine, and trimethylarsine oxide were detected in 7.6%, 4.6%, 1.8%, and 0.3% of the participants, respectively (the limits of detection of 0.6-1.2 microg/l). Monomethylarsonic acid was detected in 35% of the overall population. For all participants agedor =6 years, dimethylarsinic acid (geometric mean of 3.71 microg/l) and arsenobetaine (geometric mean of 1.55 microg/l) had the greatest contribution to the total urinary arsenic levels. A relatively greater percentage contribution from arsenobetaine is seen at higher total urinary arsenic levels and from dimethylarsinic acid at lower total urinary arsenic levels. For all participants agedor =6 years, the 95th percentiles for total urinary arsenic and the sum of inorganic-related arsenic (arsenic acid, arsenous acid, dimethylarsinic acid, and monomethylarsonic acid) were 65.4 and 18.9 microg/l, respectively. For total arsenic and dimethylarsinic acid, covariate-adjusted geometric means demonstrated several slight differences due to age, gender, and race/ethnicity.The data reflect relative background contributions of inorganic and seafood-related arsenic exposures in the US population. Arsenobetaine and dimethylarsinic acid are the major arsenic species present with arsenobetaine, accounting for a greater proportion of total arsenic as total arsenic levels increase.

A workshop was held from 28 February to 2 March 2006 at the National Institute of Standards and Technology (NIST) to evaluate the needs for new directions for complex matrix reference materials certified for radionuclide content, interlaboratory comparisons and performance evaluation (PE) programs. The workshop identified new radioanalytical metrology thrust areas needed for environmental, radiobioassay, emergency consequence management, and nuclear forensics, attribution, nonproliferation, and safeguards.

The interactions of DAPI with natural DNA and synthetic polymers have been investigated by hydrodynamic, DNase I footprinting, spectroscopic, binding, and kinetic methods. Footprinting results at low ratios (compound to base pair) are similar for DAPI and distamycin. At high ratios, however, GC regions are blocked from enzyme cleavage by DAPI but not by distamycin. Both poly[d(G-C)]2 and poly[d(A-T)]2 induce hypochromism and shifts of the DAPI absorption band to longer wavelengths, but the effects are larger with the GC polymer. NMR shifts of DAPI protons in the presence of excess AT and GC polymers are significantly different, upfield for GC and mixed small shifts for AT. The dissociation rate constants and effects of salt concentration on the rate constants are also quite different for the AT and the GC polymer complexes. The DAPI dissociation rate constant is larger with the GC polymer but is less sensitive to changes in salt concentration than with the AT complex. Binding of DAPI to the GC polymer and to poly[d(A-C)].poly[d(G-T)] exhibits slight negative cooperativity, characteristic of a neighbor-exclusion binding mode. DAPI binding to the AT polymer is unusually strong and exhibits significant positive cooperativity. DAPI has very different effects on the bleomycin-catalyzed cleavage of the AT and GC polymers, a strong inhibition with the AT polymer but enhanced cleavage with the GC polymer. All of these results are consistent with two totally different DNA binding modes for DAPI in regions containing consecutive AT base pairs versus regions containing GC or mixed GC and AT base pair sequences. The binding mode at AT sites has characteristics which are similar to those of the distamycin-AT complex, and all results are consistent with a cooperative, very strong minor groove binding mode. In GC and mixed-sequence regions the results are very similar to those observed with classical intercalators such as ethidium and indicate that DAPI intercalates in DNA sequences which do not contain at least three consecutive AT base pairs.

The operational air flow balance recommended by the Class II biological safety cabinet (BSC) manufacturer is called the nominal setpoint. Few, if any, BSCs actually operate at nominal setpoint under normal laboratory conditions. The purpose of this article is to define statistically the air flow boundaries within which a BSC will perform adequately. Performance is quantified by the microbiological aerosol tracer test as defined in the National Sanitation Foundation Standard #49. The boundaries which delineate passing test results from failing are called the performance envelope. Performance envelopes for three different models of BSCs are reported. They were determined by combining test data from at least five individual cabinets from each model. An ad hoc statistical method for calculating confidence limits around the performance envelope lines was developed to enhance the interpretation of conflicting performance envelope data. Results indicated that each model of BSC has its own unique perform...

(1990). Designing Factor Models for Different Types of Stock: What’s Good for the Goose Ain’t Always Good for the Gander. Financial Analysts Journal: Vol. 46, No. 2, pp. 25-30, 50.

In May, 2005, a partial recall of LeadCare® portable blood lead testing kits was initiated after proficiency testing revealed a negative error (mean, −25%; 95% CI, −15% to −35%) in blood lead concentrations (often called blood lead level in the US) analyzed with this device (1)(2). This bias exceeded previously recommended 95% error thresholds established with graphite furnace atomic absorption spectroscopy (3). The recall included 8 lots of defective sensors containing enough material for an estimated 500 000 patient tests distributed between September 2003 and May 2005. The LeadCare device uses an anodic stripping voltammetry method to measure lead. Capillary sampling by fingerstick is the most common method of specimen collection. Assessments of the portable units by testing of venous samples from occupationally exposed workers have demonstrated that measurements obtained with these units show an insignificant positive error that decreases as blood lead concentrations increase (4). A blood lead concentration ≥10 μg/dL (100 μg/L) has been established as the …

According to a 1997 finding, mercury was available for sale in several Chicago communities for use in spiritual or medicinal practice. Mercury used this way may impact the health of children. The Chicago Department of Public Health (CDPH) and the Centers for Disease Control and Prevention conducted a study to 1) quantify mercury exposure in biological specimens collected from a pediatric clinic or home visit in selected neighborhoods in Chicago, and 2) investigate possible sources of mercury exposure in homes.An exposure assessment study design was chosen to determine whether children living in Chicago communities that historically sold mercury were exposed to mercury vapor. We enrolled and collected biological samples from 306 children aged 2-10 years. In addition, we enrolled 42 children during a door-to-door survey of community residents. All the urine samples were analyzed for elemental or inorganic mercury. We also analyzed 43 blood samples to assess dietary mercury.Overall geometric mean urine mercury was 0.26 microg/L. Urine mercury levels did not differ among the three clinics or between the various participant groups. We did not find any association between ritualistic mercury use and exposure to mercury.Although pediatric mercury exposure does not appear to be problematic among our study population, mercury remains a potential health threat as long as it is readily available in communities. Healthcare providers should be aware of the potential for mercury exposure. Physicians and patients may call the National Poison Control Centers (1-800-222-1222) for information about diagnosis, testing, and treatment for all types of exposures, including exposure to mercury. Professionals are available 24 hours a day.

Although the maternal fish consumption is supposed to have beneficial effects on development of infants, it may be harmful for child cognitive development since fish is a common source of methylmercury.Purpose of the study was to describe the usual pattern of fish consumption during pregnancy in Poland and explain the variability of prenatal mercury exposure due to fish intake by mothers. The other endpoint of the study was the assessment of the cognitive and psychomotor development of infants related to prenatal mercury exposure over the 3-year follow-up.The study sample consisted of 374 infants born at 33-42 weeks of gestation between January 2001 and March 2003 to mothers attending ambulatory prenatal clinics in the first and second trimesters of pregnancy. Total mercury level in whole cord blood was measured and the Bayley Scales of Infant Development (BSID-II) was used to assess the mental (MDI) and psychomotor developmental index (PDI) in children at 12, 24 and 36 months of age.Self-reported weekly amount of fish consumption during the first two trimesters of pregnancy correlated positively with umbilical cord mercury concentrations (r(s)=0.22, p0.0001). The corresponding correlation coefficient for the fish consumption in the third trimester of pregnancy was 0.21, p0.0001. There was an inverse association between mercury exposure and both MDI (beta regression coeff.=-2.8, p=0.01) and PDI scores (beta coeff.=-2.3, p=0.04) at 12 months of age. Subsequent BSID-II testing at 24 and 36 months did not confirm significant association between exposure and cognitive or psychomotor function. The estimates of association between mercury prenatal exposure and the development of infants, which were based on the longitudinal analysis of all BSID-II measurements done in the follow-up (generalized estimating equations statistical model) showed that the performance deficit observed at 12 months of age was of border significance.

Objectives: The particular purpose of our study was to assess the impact of environmental tobacco smoke (ETS) on the individual variability of blood lead levels in pregnant women as earlier publications demonstrated the increased blood lead in smokers. Materials and Methods: The material consisted of 240 pregnant women who participated in a prospective cohort study on vulnerability of the fetus and infant to environmental hazards. The enrolment included only non-smoking women with singleton pregnancies between the ages of 18-35 years. Whole blood lead concentrations were determined using inductively coupled plasma mass spectrometry. Results: On average, blood-lead measured in pregnant women at delivery was low (GM = 1.7 mg/dL; 95% CI:1.6-1.8 mg/dL) and none of them showed levels above 4.0 mg/dL, but persons reporting exposure to ETS had significantly higher blood lead level (GM = 1.9 mg/dL; 95%CI:1.8-2.1 mg/dL) than those free from this exposure (GM = 1.6 mg/dL; 95%CI:1.5-1.7 mg/dL). In order to single out the effect of the ETS exposure from the confounding variables, we used the stepwise multivariate linear regression for log blood-lead in maternal blood as dependent variable and a set of independent variables, such as age, weight of women before pregnancy and their education level. The results of the analysis showed that all the independent variables included in the model explained 11% of total blood-lead variability among the study women. The strongest component of variance was attributed to ETS exposure (5%), age (3%), education level (2%) and weight (1%). Inclusion into the model of other variables, e.g., residence area and traffic intensity did not improve the proportion of explained variability. Conclusions: The reason for higher levels of blood-lead in the ETS-exposed women may result from the fact that tobacco smoke contains lead. However, it is possible that inhaled tobacco smoke also increases the absorption of lead from particulate matter deposited in the bronchial tree.

Urine iodine has been measured in the U.S. population by the National Health and Nutrition Examination Survey (NHANES) since 1971. A downward trend was noted between NHANES I (320 +/- 6 microg/L in 1971-1974) and NHANES III (145 +/- 3 microg/L in 1988-1994). This report presents data from NHANES 2001-2002 that indicates that the U.S. median urine iodine (UI) level has stabilized since the initial drop between NHANES I and NHANES III. The median UI concentration in the U.S. population in NHANES 2001-2002 was found to be 167.8 microg/L (95% confidence interval [CI] 159.3-177.6). The NHANES 2001-2002 data confirm the current stability of the U.S. iodine intake and continued adequate iodine nutrition for the country.

A new crystalline polymorph of cyclo-(Cp*Sb)4 has been crystallographically characterized that contains the mostly acutely angled four-membered, homoatomic ring system known (Sb−Sb−Sb = 76.1(1)°). In the previously reported form, the Cp* and Sb4 ring centroids (viewed along the C−Sb bond) are anti; in the new form the Cp* ring rotates over 100° to a more crowded gauche form. The new form melts at a temperature 72 °C higher than the one previously reported and is about 15% more dense. While the Sb−Sb ring distances are normal (2.836(1) A), the transannular Sb···Sb distances are the shortest known for antimony (3.518(1) A) and apparently provide a stabilization that compensates for the extreme ring distortion.

BACKGROUND: Field-portable instruments can offer expeditious analytical results to health professionals in field settings and in areas lacking laboratory infrastructure. This study further evaluated an electroanalytical field-portable instrument, which rapidly analyzes blood lead concentrations. METHODS: A portable anodic stripping voltammetry (ASV) instrument was evaluated utilizing paired samples from 243 employees working at an elevation of approximately 3,800 meters in Peru. Each worker donated two venous blood samples, one of which was analyzed by the ASV device and the other by a reference analytical method, graphite furnace atomic absorption spectrometry (GFAAS). RESULTS: According to the GFAAS results, the mean blood lead concentration measured was 46(+/-16) mug/dl; this was significantly greater than the mean ASV measurement of 32(+/-11) mug/dl (paired t-test; P < 0.0001). The accuracy of the ASV estimation decreased as the measured blood lead concentration increased. CONCLUSIONS: The results from this investigation were significantly different from the previous study, which was conducted near sea level. The exact causes for the discrepancies between the portable ASV results from the two studies are unclear, but are thought to be related to differences in blood chemistry between the Midwestern United States and Peruvian Andes worker cohorts. Portable ASV blood lead measurements from populations living at high altitudes should be viewed with caution. Am. J. Ind. Med. 46:656-662, 2004. Published 2004 Wiley-Liss, Inc.

Objective. Some children in the United States continue to be exposed to levels of lead that increase their risk for lowered intellectual functioning and behavior problems. It is unclear whether chelation therapy can prevent or reverse the neurodevelopmental sequelae of lead toxicity. The objective of this study was to determine whether chelation therapy with succimer (dimercaptosuccinic acid) in children with referral blood lead levels between 20 and 44 μg/dL (0.96-2.12 μmol/L) at 12 to 33 months of age has neurodevelopmental benefits at age 7 years. Methods. The Treatment of Lead-Exposed Children (TLC) study is a randomized, double-blind, placebo-controlled trial that was conducted between September 1994 and June 2003 in Philadelphia, PA; Newark, NJ; Cincinnati, OH; and Baltimore, MD. Of 1854 referred children who were between the ages of 12 to 33 months and screened for eligibility, 780 were randomized to the active drug and placebo groups stratified by clinical center, body surface area, blood lead level, and language spoken at home. At 7 years of age, 647 subjects remained in the study. Participants were randomly assigned to receive oral succimer or placebo. Up to 3 26-day courses of succimer or placebo therapy were administered depending on response to treatment in those who were given active drug. Eighty-nine percent had finished treatment by 6 months, with all children finishing by 13 months after randomization. All participants received residential lead hazard control measures before treatment. TLC subjects also received a daily multivitamin supplement before and after treatment(s) with succimer or placebo. Scores on standardized neuropsychological measures that tap cognition, behavior, learning and memory, attention, and neuromotor skills were measured. Results. Chelation therapy with succimer lowered average blood lead levels for ∼6 months but resulted in no benefit in cognitive, behavioral, and neuromotor endpoints. Conclusion. These new follow-up data confirm our previous finding that the TLC regimen of chelation therapy is not associated with neurodevelopmental benefits in children with blood lead levels between 20 and 44 μg/dL (0.96–2.17 μmol/L). These results emphasize the importance of taking environmental measures to prevent exposure to lead. Chelation therapy with succimer cannot be recommended for children with blood lead levels between 20 and 44 μg/dL (0.96–2.12 μmol/L).

Humans are exposed to many environmental chemicals, some of which can potentially affect neurodevelopment. Fetuses, infants, and young children are the most susceptible to the effects of these chemicals. As part of the National Health and Examination Survey, 1999-2000, the Centers for Disease Control and Prevention analyzed biological samples for many of these chemicals in a representative sampling of the U.S. population. Concentration data of selected metals, persistent organic pollutants, organophosphorus and carbamate insecticides, and cotinine are presented. For example, the 95th percentile estimates for serum total PCBs (whole weight) in the population aged 20 years and older is about 2.7 ng/g. The 95th percentile estimates for serum dioxin total toxic equivalence in the U.S. population aged 20 years and older is between 40 and 50 pg/g lipid basis. In general, human levels of these chemicals are decreasing over time in the U.S. population. This reflects the effects of legislation, industry efforts, and changes in lifestyle/activity patterns in the U.S. population. These data will continue to be collected in 2-year cycles and thus allow changes in human levels to be followed.

The authors evaluated mean blood lead levels (BLLs) and the prevalence of elevated BLLs in children 1-6 yr of age living in Torreón, Mexico, and assessed risk factors for lead exposure in these children. The study involved a simple random sample of households in the area around a local smelter, as well as a 2-stage cluster sample of neighborhoods and households in the remainder of Torreón. The geometric mean BLL of children in this study (N = 367) was 6.0 microg/dl (95% confidence interval [CI] = 5.2, 6.8) (0.29 microM/l [95% CI = 0.25, 0.33]). Twenty percent of the children had BLLsor = 10 microg/dl (0.48 microM/l), and 5% had BLLsor = 20 microg/dl (0.97 microM/l). In multivariate analyses, distance from the smelter, amount of income, and education level of the primary caregiver predicted BLLs. In the environmental risk factor subsample (n = 124), dust and soil lead levels were associated with BLLs and distance from the smelter. BLLs in this study were moderately high, but the levels were lower than those in other smelting communities prior to remediation.

Developed nations share similar challenges to human health from commercial and agricultural chemicals that are released into the environment. Although Russia and the United States are historically distinct and unique, both countries are geographically large and economically dependent on emission-producing surface transportation. This paper describes U.S.-Russian collaborative activities that grew from a 1995 conference in Moscow that brought together environmental health investigators from both countries to discuss common concerns about the human health impact of environmental pollutants. Lead, pesticides, volatile organic compounds, and mercury were identified as contaminants of greatest concern. Collaborative studies were initiated that included collecting blood and hair samples and splitting samples for analyses in both countries, and introducing and sharing new portable blood and environmental sample analyses instruments. The findings demonstrated that hair analysis was not a good predictor of BLL and that Russian children in the first city sampled had a mean BLL of 7.7 microg/dl. Although higher than the U.S. mean, this level was below the 10.0 microg/dl CDC level of concern. This manuscript summarizes additional study results and describes their impacts on Russian policy. On-going collaborative environmental investigations are described.