Charles N. Grant

Levels of As, Cd, Pb, Cu, Se and Zn in bovine kidneys and livers in Jamaica

Paired liver and kidney samples from 100 free-range cattle in different parts of Jamaica were analyzed for essential and non-essential trace elements. We found significant enrichment of elements in the kidney (K) compared to the liver (L) with the K/L concentration ratios being 5.2 for Cd, 4.1 for Pb, 3.5 for Se and 2.1 for As, but the Cu contents of the kidney were significantly higher with the K/L ratio of 0.45. A large number of kidney and liver samples showed Cu concentrations in the ranges that were associated with deficiency effects in mammals. About 15% of the hepatic samples had Zn concentrations below 20 microg/g, suggesting that there might be zinc insufficiency in some of the animals. Positive associations were found between the metals in both the kidney and liver. On average, the intake of Cd from consumption of both bovine kidney and liver from the island was estimated to be 5.2 microg/day, equivalent to about 7% of the provisional tolerable daily intake (PTDI), although anyone who habitually consumed the few kidneys or livers with >40 microg/g cadmium may be at some risk of exceeding the PTDI. The consumption of offal from local animals did not appear to be an important dietary source of any of the essential microelements.

Activation Constants for Slowpoke and MNS Reactors Calculated from the Neutron Spectrum and k0 and Q0 Values

The relative thermal, epithermal and fast neutron fluxes were measured in the inner and outer irradiation sites of three Slowpoke reactors and one Miniature Neutron Source (MNS) reactor by the bare triple monitor method. Using the measured neutron spectrum parameters and a compilation of published k0 and Q0 values, activation constants were calculated for the most intense gamma-rays of all nuclides commonly used in NAA. The resulting table of constants can be used to standardize NAA measurements for all elements when combined with relative efficiency measurements and the measurement of the thermal neutron flux with one standard. The observed constancy of the neutron spectra suggests that these activation constants are valid for all 14 Slowpoke and MNS reactors.

Evaluation of dietary exposure to minerals, trace elements and heavy metals from the muscle tissue of the lionfish Pterois volitans (Linnaeus 1758)

Twenty-five samples of Pterois volitans caught in Jamaican waters were analyzed for 25 essential, non-essential and toxic elements using Graphite Furnace Atomic Absorption Spectrophotometry (GF-AAS), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Instrumental Neutron Activation Analysis (INAA). The mean values for calcium (355 mg/kg), copper (107 μg/kg), iron (0.81 mg/kg), potassium (3481 mg/kg), magnesium (322 mg/kg), manganese (0.04 mg/kg), selenium (0.47 mg/kg), sodium (700 mg/kg) and zinc (4.46 mg/kg) were used to estimate dietary intake. The percentage contribution to provisional tolerable weekly intake for a 70 kg male and a 65 kg female were also estimated for the toxic elements arsenic (1.28% M, 1.38% F), cadmium (0.26% M. 0.28% F), mercury (3.85% M, 4.15% F) and lead (0.17% M, 0.18% F). To further assess the risk of mercury toxicity and the role of mitigation provided by selenium, selenium-mercury molar ratios were calculated for all samples. All samples were shown to have a molar excess of selenium. In addition the suggested selenium health benefit value was calculated, and was positive for all samples. It was concluded that P. volitans appears to contribute modestly to mineral and trace element nutrition, while not being a significant contributor to dietary exposure of toxic elements.

INAA of Trace Elements in Biological Materials Using the SLOWPOKE-2 Reactor in Jamaica

The biological standard reference materials Orchard Leaves SRM 1571 and Oyster Tissue SRM 1566a was analysed by instrumental neutron activation analysis (INAA) at the International Centre for Environmental and Nuclear Sciences, Jamaica at (ICEN) and at the Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Brazil. The comparison of the results with those obtained with the more powerful reactor are used to evaluate the possibilities of INAA for the analysis of biological samples at ICENS. The detection limits, the precision and accuracy of the results obtained in both laboratories are compared. The advantages and disadvantages of the different irradiation facilities are discussed. Some results obtained for Jamaican biological samples are also presented.

Assessment of the potential health risks associated with the aluminium, arsenic, cadmium and lead content in selected fruits and vegetables grown in Jamaica

Highlights • Thirteen food crops were analysed for aluminium, arsenic, cadmium and lead.• Mean concentrations were used to calculate EDI, THQ and HI.• TCR was calculated for arsenic for all food crops.• The THQ and HI were <1 for all food crops; target cancer risk did not exceed 10−4.• The food crops evaluated pose no undue risk to the consumer.

Suspended particulates in the Jamaican atmosphere

The results of a survey of air particulates at 23 sites across Jamaica for total suspended particulates (TSP), Al, Br, Cl, Na, Pb, and V, by instrumental neutron activation analysis (INAA) and X-ray fluorescence analysis (XRF) are reported. The geometric mean of TSP values, 35 g m-3, is well within the World Health Organisations standard of 60 g m-3 for TSP, but in areas of high vehicular traffic density the TSP values exceeded this limit. The correlation coefficient between Br and Pb concentrations in the particulates was 0.92 and the Br/Pb ratio of 0.38 compares well with a ratio of 0.39 found in commercial petrol indicating that the exhaust from vehicular traffic is the major source of Pb in atmospheric particulate matter in Jamaica.

Agglomerative hierarchical clustering analysis of twenty-six rice samples analysed by instrumental neutron activation analysis and other techniques

As part of the ongoing work on the safety and security of foods grown locally and imported into Jamaica, twenty five rice brands available on the Jamaican market and one sample of locally grown brown rice were collected and analysed for 36 elements using a combination of instrumental neutron activation analysis, total reflection X-ray fluorescence, flame atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry. Quality control for each of the techniques was provided by analysis of reference materials and inter-comparisons of common elements. Agglomerative hierarchical clustering analysis performed on the raw data set identified white, parboiled and brown rice as the major clusters. The element and cluster median concentration in μg/g (for polished, parboiled and brown respectively) for each of the three clusters were Al (8.7, 11.3, 14.9), As (0.20, 0.21, 0.15), Br (12.1, 0.9, 3.4), Ca (60.4, 409.1, 112.5), Co (0.1, 0.09, 0.11), Cr (0.11, 0.10, 0.11), Cs (0.012, 0.004, 0.018), Eu (0.004, 0.004, 0.003), Cu (2.2,2.7, 3.6), Fe (13, 17, 20), K (894,1,815,2,538), La (0.009, 0.014, 0.015), Mg (340, 504, 1,303), Mn (9.7, 14.9, 28.5), Mo (0.7, 1.1, 0.8), Na (5.1, 9.9, 16.9), P (936, 2,328, 3,670), Rb (4.5, 6.1, 7.3), S (1,088,1,308, 1,321), Sb (0.004, 0.006, 0.005), Sc (0.001, 0.002, 0.002), Se (0.09, 0.17, 0.16), Sm (0.001, 0.003, 0.001), Sr (2.0, 1.9, 2.9), V (0.036, 0.041, 0.058), Zn (17.9, 15.3, 22.8). The use of agglomerative hierarchical clustering has proven to be a rapid method for the analysis of the dataset, correctly clustering rice by process that is, polished, parboiled and brown, with sub-clusters that further identified location, cultivars and an adulterated sample. The data validated here has been used to estimate the elemental contribution of rice to the Jamaican diet.

Radon Mapping of Soils in St. Elizabeth, Jamaica

Soil gas measurements of radon were made in St. Elizabeth, Jamaica using nuclear track etch detectors. The results were compared to gamma-ray spectroscopy measurements made in the laboratory on soil samples collected at the radon measurement sites. An assessment of the degree of disequilibrium of uranium and thorium was also made by comparison with neutron activation analysis, delayed neutron counting and equivalent uranium and thorium measurements. The results to date for equivalent uranium and radon show a strong correlation and indicate the possibility of soil radon mapping in Jamaica using gamma-ray spectroscopy. Three anomalous sites have been identified.

NEUTRON ACTIVATION ANALYSIS OF CADMIUM IN JAMAICAN SOILS

A procedure for the instrumental neutron activation analysis of Cd in soils with relatively high Cd content and possible inteferences is reported. Cadmium concentrations in Jamaican soils above 4 mg·kg−1 can now be reliably determined by multielemental instrumental activation analysis with an accuracy ±10% and the reasonably high throughput of 30 samples per day. Over 600 geochemical survey samples were analysed for Cd along with some 20 other long-lived elements.

Radon monitoring in sites of economical importance in Jamaica

The main task was to evaluate possible radon risk to the public and workers in four caves of economical importance. Green Grotto Cave is a large labyrinthine limestone cave, open to the tourism; kept Rn concentration in the range 30-40 Bq m(-3). Xtabil a coral limestone sea cave is part of a beach resort resulted in very low radon concentration of 10 Bq m(-3). Windsor is an intricate limestone cave system showed Rn concentration in the range 250-350 Bq m(-3). Whereas the Oxford caves, is situated in a region of high radioactivity in soil due to the bauxite mines, reached a maximum of 2592 Bq m(-3).