Biomedical subjects

G C Lalor

Publications and source records attributed to G C Lalor.

7 recordsLinked to original sources

PubMed2004

In situ gamma spectroscopy measurement of 41Ar during neutron activation analysis with the SLOWPOKE II reactor in Jamaica.

In situ gamma spectroscopy was used to measure 41Ar released into the laboratory due to the activation of air in the irradiation tubes of SLOWPOKE reactor during routine neutron activation analysis. The data obtained were used to predict the 41Ar distribution in the laboratory for various operating conditions of the reactor. The dose received by the analyst from the immersion in 41Ar was calculated to be 2.36 microSv gamma(-1), which is approximately 1% of the normal background exposure.

Air Pollutants, Radioactive↗

PubMed2004

Trace elements in Jamaican tobacco.

The concentrations of 28 elements, in hand-made cigars, "rope" tobacco and freshly picked tobacco leaves from the parish of Manchester in central Jamaica, were compared with locally packaged and imported cigarettes and cigars. Except for chromium and vanadium, which are lower in the imported products, the elemental concentrations of all the brands sold in Jamaica are rather similar. The means for aluminium, cadmium, caesium, cerium, chromium, iron, thorium, uranium, vanadium and zinc for the Manchester material exceed the maximum values of the other tobaccos. The significant concentrations of heavy metals, and especially cadmium, which is about 50 times that of commercial cigarettes, reflect the known high concentrations in the soils in the region. This tobacco is not filtered and the smoke contains 50% of the cadmium. This, and the concentrations of radioactive elements, may indicate an additional health risk compared with commercial cigarettes. A study of three samples of marijuana indicates a similar level of risk from heavy metals.

Cannabis↗

PubMed2004

Blood lead levels in children in Jamaican basic schools.

Blood lead levels (BLL) for 285 children, three to six years old, from seven basic schools located in known areas of anthropogenic pollution, and in urban and rural areas are reported. The samples were obtained by the finger-prick method and analyzed for lead by anodic stripping voltammetry. The majority of the children had blood lead levels below the now accepted limit of 10 micrograms dL-1 and there was no indication of cases that would represent medical emergencies. The present results show considerable improvement in the BLLs of children living in contaminated sites indicating the effectiveness of the previous remediation steps. Follow-up intervention work is in progress for cases of blood lead levels in excess of the recommended limit.

Child↗

PubMed2004

Cadmium levels in kidney and liver of Jamaicans at autopsy.

The cadmium concentrations in the kidneys and livers of 39 autopsy cases in Jamaica, in the age group > or = 40 years, are renal cortex: range 6.7-126 mg kg-1, mean 43.8 mg kg-1; liver: range 0.3-24.3 mg kg-1, mean 5.3 mg kg-1. The mean levels in the renal cortex are higher for women than for men but not so significantly, nor are the differences between smokers and non-smokers clear. The observed values are considered high, second only to Japan where cadmium related health impairments have occurred, and nearly twice as high as the values reported from Austria, Australia, the United Kingdom and Sweden. The Jamaican cases were from areas with relatively low soil-cadmium concentrations, and the corresponding values are likely to be significantly higher in central Jamaica where the soil contains unusually high levels of cadmium. An examination of possible contributions of cadmium intake to renal problems in Jamaica now appears to be necessary.

Adult↗

PubMed2003

Thermoluminescence dosimetry in the Caribbean.

The results of five years of radiation monitoring of 590 radiation workers in Jamaica and an additional 88 in Barbados and The Turks and Caicos Islands show that the annual dose absorbed by Caribbean radiation workers is, with a single exception, well within the internationally accepted limits of 20 mSv per year. There were few cases of relatively high exposures. The dose equivalent of the radiation workers by category agrees with international trends; workers in nuclear medicine receive the highest doses and dental radiologists the lowest. The collective Effective Dose Equivalent has been calculated for each of the monitored populations and certain trends identified. The risk for development of fatal cancers from the occupational doses reported was very low. Consistent monitoring will identify aberrant conditions quickly and help maintain that record.

Caribbean Region↗

PubMed2001

Multivariate outlier detection and remediation in geochemical databases.

In this study, outliers are classified into three types: (1) range outliers; (2) spatial outliers; and (3) relationship outliers, defined as observations that fall outside of the values expected from correlation within the dataset. The multivariate methods of principal component analysis (PCA), multiple regression analysis (MRA) and an autoassociation neural network (AutoNN) method are applied to a dataset comprising 203 samples of rare earth element (REE) concentrations in soils of Jamaica which shows the expected good correlations between the elements. PCA is shown to be effective in detection of high value range outliers, while AutoNN and MRA are effective in detection of relationship outliers. A backpropagation neural network was used to predict the 'expected values' of the outliers. Four obvious relationship outliers with unexpected low Sm concentrations were selected as an example for remediation. The predicted Sm values were confirmed on remeasurement. Neural network methods, with the advantages of being model-free and effective in solving non-linear relationship problems, appear to provide an automated and effective way for the quality control of environmental databases.

Databases, Factual↗

PubMed1998

Undernutrition and elevated blood lead levels: effects on psychomotor development among Jamaican children.

OBJECTIVE: We examined whether or not the effect of elevated blood lead levels on children's psychomotor development was modified by their nutritional status. DESIGN: Anthropometry, developmental quotients (DQs), blood lead levels and haemoglobin were measured in lead exposed and unexposed children with different levels of nutritional status. Social background and maternal height and verbal intelligence were also measured. Testers, anthropometrists and interviewers established reliabilities with a trainer before the study began. SETTING: Children were from two suburban areas in Kingston, Jamaica. All measurements on the children were carried out at a research unit. Social background and maternal measurements were carried out at the children's homes. SUBJECTS: The exposed group comprised 58 children (3-6 years) attending the same preschool which was situated in a lead contaminated environment. The unexposed group comprised 53 children attending a nearby preschool without lead contamination. RESULTS: The exposed children had significantly higher blood lead levels and lower DQs, and their homes had poorer facilities than the unexposed children. The deficit in DQ was greater (10.6 points) among children with weight for height less than -1 SD (National Center for Health Statistics references) than among better nourished children (2 points). CONCLUSIONS: Undernourished children exposed to lead may have more serious developmental deficits than better nourished children.

Child↗