Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “multiple exposures”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 577 records · Page 32Linked to original sources
PubMed1993

Opioid physical dependence development in humans: effect of time between agonist pretreatments.

We examined the effect of morphine pretreatment spacing on intensity of subsequent precipitated withdrawal response to test the hypothesis that withdrawal intensity would be inversely related to pretreatment spacing. Subjects were ten nondependent male volunteers who reported using opioids an average of 2.5 times per week. Three IM morphine injections (each 18 mg/70 kg) were administered during each of four experimental conditions. The experimental conditions involved spacing injections at 12-, 24-, 48- or 72-h intervals. Naloxone (10 mg/70 kg IM) was administered 24 h after the last morphine exposure. A comparison condition was included in which a naloxone challenge was given at 24 h following a single IM morphine pretreatment (18 mg/70 kg). Subject rated measures of symptoms and observer-rated measures of signs indicated that withdrawal intensity was inversely related to the morphine spacing interval and in particular that intensity of withdrawal precipitated after three pretreatments spaced at 12-h intervals was greater than that precipitated after a single morphine pretreatment. Physiological data supported a more intense withdrawal response in the 12-h spacing condition and provided evidence of overshoot on blood pressure and skin temperature measures. These findings are pertinent to the transition between acute and chronic physical dependence; they suggest that there is a temporal window during which repeated opioid administrations result in escalation of physical dependence but that dependence levels after widely spaced multiple exposures may be no greater than after a single exposure.

Adult↗
PubMed2005

A long-term study of the effects of diazinon on sleep, the electrocorticogram and cognitive behaviour in common marmosets.

The long-term sequelae of exposure to low doses of organophosphate compounds are ill defined, with effects variously reported on a range of indices of central nervous system functions such as sleep, cognitive performance and electroencephalogram (EEG). These indices were examined in common marmosets exposed to a range of doses of the organophosphorous sheep dip, diazinon. Cognitive performance was assessed by means of elements from the Cambridge Neuropsychological Test Automated Battery (CANTAB), and radiotelemetry techniques were employed to monitor the electrocorticogram and sleep patterns. Data were collected for 12 months following intramuscular administration of a single dose of diazinon (10, 90 or 130 mg.kg (-1)) or vehicle. Although high levels of erythrocyte acetylcholinesterase (AChE) inhibition (up to 82%) and short-term changes in sleep patterns were seen, there was no evidence of biologically significant long-term changes in any measures. The effects of multiple exposures, impurities or mixtures of OP compounds remain to be investigated.

Acetylcholinesterase↗
PubMed2005

Exposure of orbital implants wrapped with polyester-urethane after enucleation for advanced retinoblastoma.

PURPOSE: Enucleation is the main form of treatment for advanced retinoblastoma. The major complication of this procedure is orbital implant exposure. Different implants and wrapping materials are currently in use. The aim of the current study was to analyze the complications associated with the use of polyester-urethane, an artificial dura substitute, as a wrapping material for enucleation in advanced retinoblastoma. METHODS: A retrospective review of 32 cases (28 patients), who were treated with enucleation for advanced retinoblastoma, was performed. The age of the patients ranged between 3 months and 6.7 years (median, 19 months). Additional chemotherapy was administered in 12 cases. The removed eyeball was replaced either with a silicone implant and polyester-urethane wrapping (13 cases) or hydroxyapatite, silicone-hydroxyapatite, or polyethylene implants without additional wrappings (19 cases). The follow-up period ranged from 7 months to 5.9 years (median, 22.4 months). Statistical analysis was performed using the Kaplan-Meier method. RESULTS: Single or multiple exposures occurred in 22% of cases (7/32). There were 6 exposures (46%, 6/13) in the group with polyester-urethane wrapping compared with only 1 exposure (5%, 1/19) in the implants without wrapping. This difference was statistically significant (p=0.0236). None of the other analyzed factors (additional chemotherapy, surgeon, age of the patient, or size of the implant) demonstrated a significant correlation to implant exposures. CONCLUSIONS: Wrapping of orbital implants with polyester-urethane resulted in a high rate of implant exposures after enucleation for advanced retinoblastoma. In this series, the best results were achieved with integrated implants without additional wrapping.

Child↗
PubMed2005

Effects of repeated in vivo inhalant nitrite exposure on gene expression in mouse liver and lungs.

Exposure to inhalant organic nitrites (drugs of abuse commonly known as "poppers") has been reported to enhance tumor growth in mice, but the mechanism is not fully defined. This study examined the effect of repeated in vivo nitrite exposures on gene expression in the mouse liver and lungs using a gene array panel of 94 cancer- and angiogenesis-related genes. Using 2-fold change as a threshold criterion, repeated nitrite exposure was found to alter the expression of 65 and 23 genes in the liver and lungs, respectively. Six genes were significantly upregulated (p<or=0.05), viz., those encoding VEGF, VEGFD (vascular endothelial growth factor A and D, respectively) in the lungs and FGF1, FGF4 (fibroblast growth factor 1 and 4, respectively), Hsp70 (heat shock 70kDa protein 4), and PF4 (platelet factor 4) in the liver. mRNA encoding HO-1 (heme oxygenase-1) and Smad7 were marginally (p=0.057) stimulated in the liver. Follow-up studies in the liver revealed significant nitrite-induced expression of VEGF protein and mRNA. Immuno-staining of liver slices revealed that the increased hepatic VEGF expression resided mainly in hepatocytes. Stimulation of hepatic VEGF expression by ISBN was not different in endothelial nitric oxide synthase (eNOS) knockout vs. wild-type mice. In conclusion, multiple exposures to inhalant nitrite appeared to cause alteration in the expression of a number of genes relating to cancer and angiogenesis, including VEGF. eNOS presence did not appear to be essential for nitrite-induced VEGF expression. These studies demonstrate that in vivo exposure to inhalant nitrites results in changes in the angiogenesis cascade.

Administration, Inhalation↗
PubMed1988

Conditioned augmentation of natural killer cell activity. Independence from nociceptive effects and dependence on interferon-beta.

Injection of mice with 20 micrograms polyinosinic: polycytidylic acid (Poly I:C) after exposure to camphor odor results in a conditioned augmentation of natural killer cell (NK) activity. In this study, we show that the conditioned response is not the result of nociceptive stimulation and that interferon-beta (IFN), but not IFN-alpha can replace Poly I:C as the unconditioned stimulus (US). Two conditioned stimuli (CS) were used with equivalent results. A combination CS consisting of a novel taste (saccharin) and a 125 mg/kg injection of LiCl that induces gastric upset was paired with a Poly I:C or IFN-beta (1 X 10(4) IU) injection. This resulted in an augmentation of NK activity when the conditioned animals were reexposed to the saccharin-LiCl CS. In addition, an identical conditioned response was elicited when a camphor odor CS was paired with either of these US. To test whether the conditioned response might be an artifact not detected by our controls, a mock conditioning experiment was performed, which assessed the differential effect of multiple exposures to the saccharin-LiCl CS without a CS/US pairing. The mock conditioned group was significantly suppressed relative to saline treated controls, whereas the mock nonconditioned group and the mock conditioned group that was not reexposed to the CS after conditioning did not show significant suppression. This indicates that the augmentation observed in the conditioned group after CS/US pairing was not the result of exposure to the CS itself. Small doses of Poly I:C (5 micrograms or 2.5 micrograms) given on days 3 and 5 (or on day 5 only) to boost NK activity had the effect of increasing the magnitude of the conditioned response measured on day 6. In addition, an identical conditioned response was observed when the interval between the CS/US pairing and the later CS exposures was changed, which places the test for the conditioned response either on day 6 (CS given on days 3 and 5) or day 10 (CS given on days 7 and 9). These results show that the observed conditioned enhancement of NK activity in conditioned animals is not caused by any nociceptive properties of the CS itself and is dependent on the IFN-beta produced after Poly I:C injection in the conditioned paradigm.

Adjuvants, Immunologic↗
PubMed2005

The temporal and spatial variations of acid aerosols in the geothermal area of metropolitan Taipei, Taiwan.

This study involved sampling over 1 year of data on exposure to acid aerosols in the geothermal area of metropolitan Taipei. The temporal and spatial variations of the concentrations of acid aerosols were assessed by sampling at three sites: A, B, and C. Results indicate that the SO2 concentrations lead the concentrations of other acid aerosols at site C because two active fumaroles surround this site. The mean SO2 concentrations at sites A, B, and C were 2.4, 2.4, and 6.2 ppb. Previous studies have found that H2S levels were highest at site C. However, the SO4(-2) and H+ concentrations among the three sites were similar. The mean aerosol SO4(-2) concentrations were 7.0, 5.7, and 5.7 microg m(-3) at sites A, B, and C, respectively; their H+ concentrations were 5.5, 4.2, and 5.4 nmol m(-3). No seasonal variations are observed for most of the acid aerosols in the geothermal area except that the types of hot spring affect the SO4(-2) concentration nearby. The different seasonal fluctuation among the sites reflect the determinant of SO4(-2) emission from different geothermal sources. Sulfur-rich aerosols and some SO2 emitted from geothermal sources are obvious. The predominance of nitrogen-containing gases (sum of NO2 + HNO2 + HNO3) over SO2 indicates the importance of the anthropogenic origin of emissions. The effect of multiple exposures to sulfur-rich aerosol (including H2S, SO2, and SO4(-2)), H+, and nitrogen-containing aerosols on the health of nearby residents warrants concern.

Acids↗
PubMed1999

The radiation-attenuated schistosome vaccine induces high levels of protective immunity in the absence of B cells.

Radiation-attenuated cercariae of Schistosoma mansoni elicit consistently high levels of protective immunity in mice. The cell-mediated pulmonary effector mechanisms have been well characterized but the role of B cells and antibodies remains ill defined. We have compared the immune responses of B-cell-deficient (muMT) mice and their wild-type (WT) counterparts following exposure to the attenuated vaccine. Both groups mounted a T helper type 1 (Th1)-biased response in the skin-draining lymph nodes after vaccination. Interferon-gamma was the dominant cytokine secreted by airway leucocytes after challenge in both muMT and WT mice, but there was a somewhat greater Th2 component in the former animals. The cellular infiltrates observed in the airways, and the pulmonary effector foci, were of similar composition in the two groups although some large foci were present in the muMT mice. There was a marked dichotomy in the protection induced in muMT animals by a single vaccination, with two-thirds showing levels similar to their WT counterparts, demonstrating that cell-mediated mechanisms alone can provide adequate protection. The remaining muMT mice had a mean worm burden identical to that of their challenge controls. A possible explanation is that a proportion of the muMT animals have a genetic defect closely associated with the mu-heavy-chain locus on chromosome 12, which affects their ability to mount a protective cell-mediated response. Three vaccinations enhanced the immunity of WT animals, most likely by augmenting antibody-mediated mechanisms. In contrast, no enhancement was seen in muMT mice, suggesting that the cell-mediated response is not boosted by multiple exposures to attenuated larvae.

Animals↗
PubMedDate not supplied

HIV neutralizing IgA in exposed seronegative subjects recognise an epitope within the gp41 coiled-coil pocket.

Human immunodeficiency virus (HIV)-specific IgA can be detected in cervical secretions, saliva, and sera of HIV-infected and HIV-uninfected individuals with a known exposure to the virus. IgA from HIV-uninfected exposed seronegative individuals (ESN) neutralize in vitro primary strains of HIV-1. We analyzed the epitopes of HIV recognized by serum HIV-specific IgA of ESN individuals to identify the antigenic correlates of HIV neutralization in exposed-uninfected subjects, and to verify whether different epitopes would be recognized by HIV-specific IgA of ESN and of HIV-infected patients. Results confirmed that HIV-neutralizing IgA are detected in sera of ESN and showed that neutralization of primary HIV strains is mediated by the recognition of different epitopes in HIV-infected patients and ESN. Thus, whereas IgA of HIV+ individuals recognize epitopes expressed both within gp120 and gp41, IgA of ESN exclusively bind to gp41-expressed epitopes. Epitope mapping revealed that the epitope recognized by serum IgA of ESN on gp41 is restricted to aa 581-584 (LQAR) and corresponds to coiled coil pocket in the alpha helic region. In contrast, the epitope seen by IgA of HIV-infected patients on gp41 is identified by two regions; the first is contained within the cystein loop (aa 589-618), the second correspond to C terminal region in the extra membrane region of gp 41 (aa 642-673). Thus, we have identified and characterized the epitopes that mediate neutralization of HIV in individuals in whom infection does not occur despite multiple exposures to the virus. These results have important implications for the development of a new therapy against HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Exposure pathway assessment at a copper-beryllium alloy facility.

Controlling beryllium inhalation exposures to comply with regulatory levels (2 micro g m(-3) of air) does not appear to prevent beryllium sensitization and chronic beryllium disease (CBD). Additionally, it has proven difficult to establish a clear inhalation exposure-response relationship for beryllium sensitization and CBD. Thus, skin may be an important route of exposure that leads to beryllium sensitization. A 2000 survey had identified prevalence of sensitization (7%) and CBD (4%) in a beryllium alloy facility. An improved particulate migration control program, including dermal protection in production areas, was completed in 2002 at the facility. The purpose of this study was to evaluate levels of beryllium in workplace air, on work surfaces, on cotton gloves worn by employees over nitrile gloves, and on necks and faces of employees subsequent to implementation of the program. Over a 6 day period, we collected general area air samples (n = 10), wipes from routinely handled work surfaces (n = 252), thin cotton glove samples (n = 113) worn by employees, and neck wipes (n = 109) and face wipes (n = 109) from the same employees. In production, production support and office areas geometric mean (GM) levels of beryllium were 0.95, 0.59 and 0.05 micro g per 100 cm(2) on work surfaces; 42.8, 73.8 and 0.07 micro g per sample on cotton gloves; 0.07, 0.09 and 0.003 micro g on necks; and 0.07, 0.12 and 0.003 micro g on faces, respectively. Correlations were strong between beryllium in air and on work surfaces (r = 0.79), and between beryllium on cotton gloves and on work surfaces (0.86), necks (0.87) and faces (0.86). This study demonstrates that, even with the implementation of control measures to reduce skin contact with beryllium as part of a comprehensive workplace protection program, measurable levels of beryllium continue to reach the skin of workers in production and production support areas. Based on our current understanding of the multiple exposure pathways that may lead to sensitization, we support prudent control practices such as use of protective gloves to minimize skin exposure to beryllium salts and fine particles.

Air Pollutants, Occupational↗
PubMed1996

Effects of multiple sterilization on surface characteristics and in vitro biologic responses to titanium.

PURPOSE: This study evaluates the surface changes and effects on in vitro cell attachment and spreading brought about on prepared commercially pure titanium by multiple exposures to common sterilization methods. MATERIALS AND METHODS: Discs of commercially pure titanium were prepared to approximate the surface roughness of commercially available bone miniplates. Samples underwent sterilization by exposure to ultraviolet light; ethylene oxide sterilization (1, 5, or 10 cycles); or by steam autoclaving (1, 5, or 10 cycles). Representative surfaces from these sterilization groups were examined using a series of surface analytical techniques including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES), and contact angle measurements. Cell attachment assays using murine fibroblasts were then performed on titanium surfaces from each sterilization group and on tissue culture plastic controls. Sterilized surfaces contained O, C, and N contaminants, which affected surface energetics. Mean percent cell attachment values for each group were obtained for periods of up to 1 hour. Representative samples from each group were examined using SEM to ascertain cell spreading and morphology for each sterilization group. RESULTS: Ultraviolet (UV) sterilized surfaces showed no changes from the unsterilized state macroscopically or under SEM. UV surfaces showed cell attachment levels similar to control surfaces at all intervals, and a chronologic progression of cell spreading. Ethylene oxide-sterilized surfaces showed occasional bluish discoloration and a microscopic particulate contaminant, resulting in modest decreases in cell attachment levels without strong correlation to numbers of sterilization cycles. Autoclaved surfaces generally showed the greatest discoloration and heaviest particulate contamination. Cell attachment levels were lower, and cell spreading was diminished compared with the ethylene-oxide-treated group. CONCLUSIONS: Both ethylene oxide and steam autoclave sterilization contaminated and altered the titanium surface, resulting in decreased levels of cell attachment and spreading in vitro. Although corroborative in vivo experiments should be conducted, the results of this study indicate that some multiple sterilization regimens for metallic materials may pose serious biologic concerns.

3T3 Cells↗
PubMed1998

The adaptive response in radiobiology: evolving insights and implications.

The first of the regularly reproducible experiments to show that very low doses of ionizing radiation, like very low doses of chemical agents, could induce mechanisms whereby cells become better fit to cope with subsequent exposures to high doses were carried out on the induction of chromosome aberrations in cultures of human lymphocytes. If cells that had been exposed to a very low dose (1 cGy) of X rays were subsequently exposed to a relatively high dose (1 Gy), approximately half as many chromosome breaks were induced. Subsequent experiments showed that this adaptive response to low doses requires a certain minimal dose before it becomes active; occurs only within a relatively small window of dose; is dose-rate dependent; and depends on the genetic constitution of the people or animals exposed, with some being unresponsive. It was further shown that the response to the low-dose preexposure was not instantaneous but took approximately 4 to 6 hr to become fully active, and could be prevented if during this period protein synthesis was inhibited, i.e., a necessary protein (enzyme) was being induced. In fact, subsequent experiments with two-dimensional gel electrophoresis showed new proteins in cells irradiated with 1 to 2 cGy. The adaptation induced by low doses of radiation was therefore attributed to the induction of a novel efficient chromosome break repair mechanism that if active at the time of challenge with high doses would lead to less residual damage. This hypothesis was strengthened by a series of experiments in which it was found that inhibitors of poly(ADP-ribose)polymerase, an enzyme implicated in DNA strand break rejoining, could prevent the adaptive response. Although the phenomenon is well established in cellular systems, it is still problematical as to whether or not it will have any utility in establishing risks of ionizing radiation to humans. Newer experiments have now been carried out on the mechanisms underlying the effect and whether or not the effect can manifest itself as a decrease in the number of induced cancers and radiation-induced mortality. Experiments with restriction enzymes now indicate that double-strand breaks in DNA can be triggering events in adaptation. In addition, preliminary experiments on the survival of whole-body irradiated mice have shown that multiple exposures to low adapting doses can have profound effects on survival, and other experiments have shown that adaptation can affect the induction of thymic lymphoma in irradiated mice. It therefore appears that the initial experiments behind the adaptive response have led to a vigorous worldwide effort to understand the basic mechanisms behind it. This effort is stimulated both by a desire to understand the basic cell biology behind the response and a desire to see if indeed this phenomenon affects the estimation of risks of low-level radiation exposure.

Adaptation, Physiological↗
PubMed1988

Human immunodeficiency virus infection in sexually active wives of infected hemophilic men.

PURPOSE: Because of past multiple exposures to contaminated coagulation factor concentrates, the prevalence of human immunodeficiency virus (HIV) infection among adult hemophilic men in the United States is reported to range from 75 to 90 percent. The risk of HIV transmission through a long-term monogamous heterosexual contact can be estimated by studying the spouses of hemophilic subjects since these couples generally do not abuse intravenous drugs, usually maintain stable monogamous relationships, and are usually free of other risk factors. Our purpose was to gather data on the risk of heterosexual transmission of HIV infection in the context of long-term monogamous relations according to the duration of HIV antibody seropositivity and of HIV antigenemia in HIV-infected hemophilic men, and their sexual habits. SUBJECTS AND METHODS: Infection with HIV was studied in 14 sexually active spouses of infected hemophilic men who had been HIV antibody reactive for a mean of 46 +/- 23 (SD) months. One half of the hemophilic men studied had overt HIV antigenemia for a mean duration of 27 +/- 23 (SD) months; six of the men studied fulfilled clinical criteria for the diagnosis of acquired immunodeficiency syndrome (AIDS). All 14 couples were sexually active in a strictly monogamous fashion, in marriages of 13.5 +/- 10.5 (SD) years with an average reported frequency of four sexual encounters per month (range: one to 12). Plasma samples of the hemophilic husbands were retrospectively analyzed for HIV and hepatitis B virus markers. Blood samples were obtained from female spouses on at least two occasions, six months apart. Comprehensive questionnaires regarding sexual habits and other risk factors were filled out by each couple; during this interview, the couple was counseled about safe sexual practices. None of the couples studied used condoms prior to January 1986. RESULTS: Antibodies to HIV developed in only one of the 14 wives. At the time when this seroconversion was detected, her husband, in whom AIDS developed, had been reactive for HIV antibody for 49 months, and showed positive findings for HIV antigen for 26 months. No additional risk factors were identified for this couple. The infected female spouse, however, has a 14-year history of multiple sclerosis, and had been treated with immunosuppressant intermittently. Despite a significantly reduced number of CD4 lymphocytes, she has remained clinically asymptomatic for 17 months since seroconversion. HIV antibodies did not develop in any of the 13 remaining wives, despite the frequent practice of oral sex by six couples and reports of occasional anal intercourse by another couple.(ABSTRACT TRUNCATED AT 400 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed2000

Mortality from multiple sclerosis and exposure to residential and occupational solar radiation: a case-control study based on death certificates.

OBJECTIVES: To explore whether mortality from multiple sclerosis is negatively associated with exposure to sunlight. METHODS: Two case-control studies based on death certificates were conducted for mortality from multiple sclerosis and non-melanoma skin cancer (as a positive control) to examine associations with residential and occupational exposure to sunlight. Cases were all deaths from multiple sclerosis between 1984 and 1995 in 24 states of the United States. Controls, which were age frequency matched to a series of cases, excluded cancer and certain neurological deaths. The effects of occupational exposure to sunlight were assessed among subjects with usual occupations requiring substantial activity, so as to exclude those whose indoor jobs resulted from disabilities subsequent to the onset of the disease. Multiple logistic regression analyses were applied, with adjustment for age, sex, race, and socioeconomic status. RESULTS: Unlike mortality from skin cancer, mortality from multiple sclerosis was negatively associated with residential exposure to sunlight (odds ratio (OR)=0.53 (multiple sclerosis) and OR=1.24 (skin cancer)). Odds ratios for the highest occupational exposure to sunlight were 0.74 (95% confidence interval (95% CI) 0.61 to 0.89) for mortality from multiple sclerosis, compared with 1.21 (1.09 to 1.34) for mortality from non-melanoma skin cancer. The OR was 0.24 for the combined effect of the highest levels of residential and occupational exposure to sunlight on multiple sclerosis, compared with an OR of 1.38 for skin cancer. CONCLUSIONS: In this exploratory study, mortality from multiple sclerosis, unlike mortality from skin cancer, was negatively associated with both residential and occupational exposure to sunlight.

Adult↗
PubMed1988

Q fever. A call to heighten our index of suspicion.

The prevalence of Q fever infection is probably underestimated. In Michigan, the first two reported human cases of Q fever occurred in 1984. The case-patients lived in adjacent, rural counties and had multiple exposures to goats. We conducted a serosurvey of goat owners and a reference population to compare the prevalence of Q fever antibodies in the two-county area. Goat owners were almost three times more likely to be seropositive with Q fever antibodies than the reference population (43% vs 15%). Among goat owners, individual and household seropositivity prevalences were positively correlated with the number of goats, the number of positive goats, and the number of goat births on the farm. Q fever should be considered more often in the differential diagnosis of patients with compatible illness, especially those with frequent animal contact.

Adolescent↗
PubMed1996

Simulation study of hierarchical regression.

Hierarchical regression - which attempts to improve standard regression estimates by adding a second-stage 'prior' regression to an ordinary model - provides a practical approach to evaluating multiple exposures. We present here a simulation study of logistic regression in which we compare hierarchical regression fitted by a two-stage procedure to ordinary maximum likelihood. The simulations were based on case-control data on diet and breast cancer, where the hierarchical model uses a second-stage regression to pull conventional dietary-item estimates toward each other when they have similar levels of food constituents. Our results indicate that hierarchical modelling of continuous covariates offers worthwhile improvement over ordinary maximum-likelihood, provided one does not underspecify the second-stage standard deviations.

Bayes Theorem↗
PubMed1998

Low cyanide exposure from consumption of cassava in Dar es Salaam, Tanzania.

The extent of cyanide exposure from cassava consumption was studied in low income suburbs of Dar es Salaam, Tanzania. Mean cyanogen levels in sun-dried root pieces called makopa was 9.4 (range 0-79) mg HCN equivalents kg(-1) dry weight. The mean glucoside and hydrogen cyanide levels were 6.4 and 3.2 mg HCN equivalents kg(-1) dry weight, respectively, while cyanohydrins were lower with a mean of 2.0 (range 0-27) equivalents kg(-1) dry weight. Food frequency interviews with 193 schoolchildren revealed that 13% of the children consumed cassava stiff porridge in the previous week. Fried cassava pieces were consumed by 82% and boiled cassava pieces by 49% of the children. The urinary thiocyanate in these children was 36 +/- 3 (mean +/- SEM) micromol l(-1) and mean urinary linamarin level was 18 +/- 1 micromol l(-1), indicating low cyanide exposure. Multiple regression analysis revealed a positive correlation between urinary thiocyanate and consumption of boiled cassava pieces as well as between urinary linamarin levels and daily intake of fried cassava pieces.

Adolescent↗
PubMed1984

Mortality from cancers of major sites in female radium dial workers.

The female radium dial workers have now experienced significant mortality from cancers other than the bone sarcomas and head carcinomas long known to be radium induced. The relationships of radium exposure to mortality from cancers of the stomach, pancreas, colon, rectum, liver, lung, breast, cervix, and corpus uteri, and from leukemia were studied in 1,285 pre-1930 dial workers. Mortality was compared with that expected from rates for US white females, with and without adjustment for local area mortality rates, and with mortality in dial workers exposed from 1930 to 1949. For the 693 cases whose body content of radium has been measured since 1955, dose-response relationships of cancer to systemic intake of radium and duration of employment were examined. Liver, pancreatic, cervical, and uterine cancers were clearly unrelated to radium exposure. Other cancers of the digestive tract appeared to be indirectly, if at all, associated with work in radium facilities. Lung cancer requires further investigation; inhalation exposures of the dial workers were reviewed. Analyses of the breast cancer data uncovered several observations inconsistent with the previously suggested causal association with radium exposure. Multiple myeloma was also reviewed. A threefold excess risk of death due to multiple myeloma has occurred, but is more closely correlated with duration of employment (a surrogate for external gamma radiation) than with radium intake.

Aged↗
PubMed1987

Mortality among workers at a butadiene facility.

Several studies of styrene-butadiene rubber (SBR) workers have reported excess cancers at various sites; however, little could be concluded concerning specific etiologic agents because of the multiple exposures encountered by these groups. The current study examined cause-specific mortality in a cohort of 2,586 male workers employed for at least 6 months between 1943 and 1979 in a butadiene manufacturing plant that supplied butadiene to two SBR plants. Standardized mortality ratios were calculated using national (NSMR) and local (LSMR) comparison populations. The all-cause NSMR was 80 (p less than 0.05) and the all-cancer NSMR was 84; the corresponding LSMRs were 96 and 76 (p less than 0.05). No significant excesses were observed for any cause of death except lymphosarcoma and reticulum cell sarcoma (NSMR = 235). When the cohort was subdivided into routine, nonroutine, and low-exposure groups, the SMRs were consistently elevated for this cause of death in all three groups. However, direct comparisons between each of the two exposure groups and the low-exposure group were inconsistent. This suggests butadiene may not be responsible for the excess, but the association deserves close attention in future studies.

Adult↗