Miguel Navarro

Mercury in pilot whales: possible limits to the detoxification process

The ability of pilot whales (Globicephala melas) to concentrate cadmium and mercury is well established. The levels of these metals were generally higher than those encountered in other species of marine mammals. The biological data have not revealed a major toxic problem in the population, and this suggests a remarkable tolerance of this species to heavy metals. Cellular distribution of mercury was carried out in liver samples. The presence of metallothionein-like proteins in the soluble fraction has been demonstrated, but 95% of mercury was mainly bound to the insoluble fraction, showing that these proteins had no role in this metal detoxification. The molar ratio between mercury and selenium suggests that the major mechanism of detoxification is through the formation of a complex Hg-Se which leads to the demethylation of mercury. The site of this process is the liver in which mercury mainly appeared as inorganic, whereas in the muscle the percentage of organic to total mercury was much higher. Nevertheless, this detoxification is limited in lactating females and in all the individuals of one school. This could be the result of changes in the diet and could constitute a toxicological risk for the species.

Determination of total arsenic levels by hydride generation atomic absorption spectrometry in foods from south-east Spain: estimation of daily dietary intake

The total concentration of arsenic in different foods from south-east Spain was determined by hydride generation atomic absorption spectrometry. Mineralization was carried out with an HNO3-HClO4 mixture in a thermostated sand bath. Arsenic determination was performed by the standard addition method. Analyses of NIST and CBR-CEC reference materials demonstrated the reliability and accuracy of the technique. The highest arsenic levels were found in seafood, cereals, meat and meat by-products. In meat and meat by-products, the total arsenic measured in meat was significantly higher than that in sausages (p<0.05). In cereals, arsenic concentrations in corn and white rice samples were significantly higher (p<0.01) than those measured in wheat by-products. Mean arsenic concentrations in cheese were statistically lower than those in other dairy products (p<0.01). New data have been provided on the total arsenic content of a variety of foods in Spain, which is important for making exposure estimates. The estimated daily intake of total arsenic in the Spanish diet was 221 μg As day−1.

Determination of selenium in serum by hydride generation atomic absorption spectrometry for calculation of daily dietary intake

Hydride generation atomic absorption spectrometry was used to determine the selenium concentrations in 130 samples of human serum from a control group of inhabitants in the southern part of the province of Granada (Spain). The mean selenium concentration in serum was 74.9 micrograms/l. This concentration did not vary significantly (P > 0.05) in relation to the sex of the subject, with concentrations of 80.6 micrograms/l in men and 70.7 micrograms/l in women. These mean values correspond to a mean daily dietary selenium intake of 50.4 micrograms per day in men and 44.6 micrograms per day in women. A considerable number of the individuals in the study area therefore have a daily selenium intake lower than the recommended dietary allowance of 70 micrograms per day for men and 55 micrograms per day for women. Likewise, the measured selenium concentrations in the basic health zones of the area were not statistically different (P > 0.05). The differences in selenium concentration between subjects in coastal zones and mountainous zones are therefore not significant.

Microwave dissolution for the determination of mercury in fish by cold vapour atomic absorption spectrometry

Abstract A procedure is described for the determination in fish species from the Mediterranean Spanish coast by cold vapour atomic absorption spectrometry. The samples were decomposed with nitric acid in a microwave acid digestion bomb. A certified reference sample was analysed and the results obtained agreed well with the certified values. The limit of detection for the samples investigated was 0.195 ng ml −1 . The concentrations of mercury in fish ranged from 0.033 to 1.211 μg g −1 .

Zinc levels in foods from southeastern Spain: relationship to daily dietary intake

The zinc content of 300 food and 79 beverage samples was determined using flame atomic absorption spectrometry. Sample recoveries, repeatability, and analyses of NIST and CBR-CEC reference materials demonstrated the reliability and accuracy of this technique. Mean zinc concentrations varied from 0.02 μg/ml in fresh water to 71.0 μg/g (fresh weight) in pork liver. The daily dietary intake of zinc for inhabitants of southeastern Spain was estimated to be 10.1 mg (5.5, 4.0, 0.5, and 0.1 mg Zn/day per person from foods of animal and vegetable origin, drinks, and other foods, respectively). Zinc levels found in high protein foods (meat, fish, milk products, eggs, dry fruits, cereals and legumes) were significantly higher than those found in food with a low protein content (vegetables, fruits and drinks) (p < 0.001). A significant linear correlation between zinc levels and the corresponding protein content of cereals, legumes and dry fruits was found (r = 0.754, p < 0.005). Zinc concentrations in milk samples were significanlty modified by the thermal treatment (p < 0.001), and the skimming (p < 0.05) and calcium enrichment processes (p < 0.001). Shellfish zinc levels were also significantly higher than those measured in fish (p < 0.05). Mean zinc concentrations found in cheese were statistically higher than those determined in the remaining milk products (p < 0.001). Zinc levels measured in distilled beverages were also statistically lower than those found in fermented ones (p < 0.001).

The effect of industrial pollution on mercury levels in water, soil, and sludge in the coastal area of Motril, Southeast Spain

The total concentration of mercury was determined in samples of water, soil and sludge from the Mediterranean coastal area of Southeast Spain (Motril), where Hg contamination is produced primarily by a local paper mill. Samples were taken at surface level in a 5 Km radius from the factory. The total Hg concentrations varied from 0.117 to 0.760 μg/g in soil and sludge, and from ND to 2.088 μg/L in water. A negative correlation was observed between the distance of the sampling station from the mill and the concentration of Hg in the soil and sludge samples. Similarly, an increase in Hg concentration was observed in the freshwater and wastewater after passing close to the factory.

Serum copper concentration in HIV-infection patients and relationships with other biochemical indices

We have determined the degree of abnormalities in serum copper concentrations in HIV-seropositive individuals. The study was conducted at the Virgen de las Nieves Universitary Hospital in Granada (Spain). A total of 142 HIV-infected individuals and 84 control subjects were included in the study. The HIV-infected subjects were divided into three groups following the 1993 criteria of the Center for Disease Control and Prevention (Atlanta, USA). Serum copper levels in HIV-infected subjects were significantly higher than those found in control individuals (P < 0.001). Moreover, there were no statistically significant (P > 0.05) differences in serum Cu levels among the three groups considered although serum Cu enhancement occurred at the beginning of the infection process (group A). This increase then remains constant in advanced stages of HIV infection (groups B and C). The mean serum Cu concentration in women (1.41 mg/l) was not significantly higher than that found in men (1.39 mg/l) (P > 0.05). Linear regression analyses between serum copper concentrations and nutritional or biochemical indices (prealbumin, albumin, transferrin, lymphocytes CD4, body mass index, weight) were not statistically correlated (P > 0.05). These data suggest that copper which is an acute phase reactant, may be a useful marker of HIV activity and progression to AIDS as in other chronic infective diseases.

Serum selenium levels during normal pregnancy in healthy Spanish women.

In this study, we determined selenium concentrations in serum samples of healthy women (146 pregnant and 74 nonpregnant) living in the Mediterranean area of the coast of Granada (southeast Spain). The subjects were distributed in two groups: group A (pregnant women), divided into three categories according to the trimester of pregnancy, and group B (nonpregnant women). No significant differences were observed in the selenium levels either among pregnant women according to the trimester of pregnancy or in the group of nonpregnant women. No other significant differences were determined as regards the age of pregnant women (P > 0.05). Serum selenium levels are slightly lower during pregnancy. Considering that serum selenium levels affect the body selenium status, the concentrations determined establish the non-existence of selenium problems in the daily dietary intake with respect to maternal and fetal necessities during pregnancy.

Determination of selenium levels in dairy products and drinks by hydride generation atomic absorption spectrometry: correlation with daily dietary intake.

The selenium concentrations in different dairy products and drinks in the Mediterranean coastal area of southeastern Spain have been determined by hydride generation atomic absorption spectrometry. Mineralization was carried out with an HNO3-HClO4 mixture (4:1) in a thermostatted sand bath. Selenium determination was carried out by the standard addition method. Mean concentrations obtained in diary products varied from 6.87 ng/g (rice pudding) to 178.90 ng/g (caramel custard), and those in drinks from 0.256 micrograms/l (wine) to 2.879 micrograms/l (pineapple juice). Repeatability, expressed as relative standard deviation, ranged from 5.06% to 13.25%. The results obtained from the recovery studies were proximate to 100%. Considering the mean daily individual consumption of these foods in Andalusia (southern Spain), the daily dietary intake of selenium supplied by this source is 5.869 micrograms per person per day.

Selenium (IV) and (VI) levels in potable, irrigation and waste waters from an industrial zone in southeastern Spain

Selenium in potable, irrigation and waster waters was chemically specified in 62 stations of an industrial zone in southeastern Spain. Hydride generation atomic absorption spectrometry was the method for direct analysis of Se (IV). Prior reduction to Se (IV) by means of HCLoc was necessary for measurement of Se (VI). Se (IV) and Se (VI) concentrations ranged respectively from not detectable to 0.380 μg/l and from not detectable to 0.280 μg/l. There are no significant differences between the levels of Se (IV) or Se (VI) in the three types of water (P > 0.01). Total Se levels, Se (IV) and Se (VI) of the water in the zone are not affected by human and industrial activity. The low concentrations determined show a low selenium content in those soils through which the water of the zone is leached and drained. Se (IV) concentrations in water are low, but slightly higher than those of Se (VI); for this reason the soluble, bioavailable fraction (mainly present as SeO42−) for the crops in the zone is also low. The daily dietary intake of selenium supplied by drinking water is < 0.5 μg per person.