Anita Nilsson

Exposure to Dioxins and Dibenzofurans through the Consumption of Fish

BACKGROUND In some regions, including the Baltic Sea, fatty fish such as salmon and herring contain high levels of polychlorinated dibenzodioxins and dibenzofurans. We investigated human exposure to these potentially toxic substances in relation to the consumption of fish from the Baltic Sea. METHODS Plasma levels of 10 different dibenzofurans and 7 dioxins were analyzed in three groups of Swedish men: one group with a high intake of fish (fish eaten almost daily; n = 11), one with a moderate intake of fish (about once per week; n = 9), and one with no consumption of fish (usually because of allergy; n = 9). RESULTS Plasma levels of several of the compounds we measured were higher in the men with a high intake of fish than in those who consumed moderate amounts, and the levels were higher in those who ate moderate amounts of fish than in those who ate none. The median amounts of the most toxic dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin) were 8.0 pg per gram of plasma lipid (range, 2.0 to 13) in the high-intake group, 2.6 pg per gram (range, 1.2 to 4.2) in the moderate-intake group, and 1.8 pg per gram (range, 1.0 to 2.5) in the nonconsumers (P = 0.001 and 0.02, respectively). There were consistent and statistically significant associations between the reported amount of fish eaten and the plasma levels of several of the dibenzofurans and dioxins. CONCLUSIONS Contaminated fish such as those from the Baltic Sea are an important source of exposure to polychlorinated dibenzofurans and dibenzodioxins in persons who eat fish regularly. However, the clinical consequences of such exposure remain uncertain.

Fish as a source of exposure to mercury and selenium

In a total of 395 subjects with varying fish consumption habits, mercury levels in whole blood (B-Hg), and selenium levels in plasma (P-Se) were studied. Also, in subcohorts, mercury levels in blood cells (Ery-Hg; n = 79), plasma (P-Hg; n = 158) and urine (U-Hg; n = 125) were analysed. There were statistically significant associations between fish intake on the one hand, and B-Hg, Ery-Hg and P-Hg, on the other, but not so with U-Hg. In subjects who never had fish, the average B-Hg was 1.8 ng/g, in subjects who had at least two fish meals each week, 6.7 ng/g. Ery-Hg, and to a less extent P-Hg, were associated with levels of marine n-3 polyunsaturated fatty acids (PUFA) in serum phosphatidylcholine. P-Hg and U-Hg were associated with numbers of teeth with amalgam fillings. P-Se also correlated with fish intake. In subjects who never had fish, P-Se averaged 80 micrograms/l, in subjects who had at least two fish meals per week, 91 micrograms/l. There was an association between PUFA and P-Se. Further, there were statistically significant associations between P-Se on the one hand, and B-Hg, Ery-Hg and P-Hg on the other. The data clearly demonstrate the importance of fish for the exposure to methylmercury and selenium in the Swedish diet, and the impact of amalgam as a source of exposure to inorganic mercury.

Parameters of immunological competence in subjects with high consumption of fish contaminated with persistent organochlorine compounds

SummaryConsumption of fatty fish species, like salmon and herring, from the Baltic Sea is an important source of human exposure to persistent organochlorine compounds, e.g. polychlorinated dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs). Many of these compounds show immunotoxic and hepatotoxic effects in animals. We have now studied immunological competence, including lymphocyte subsets, in 23 males with a high consumption of fish from the Baltic Sea and in a control group of 20 males with virtually no fish consumption. The high consumers had lower proportions and numbers of natural killer (NK) cells, identified by the CD 56 marker, in peripheral blood than the non-consumers. Weekly intake of fatty fish correlated negatively with proportions of NK cells (rs = −0.32, P = 0.04). There were also, in a sub-sample of 11 subjects, significant negative correlations between numbers of NK cells and blood levels of a toxic non-ortho-PCB congener (IUPAC 126; rs = −0.68, P = 0.02) and a mono-ortho congener (IUPAC 118; rs = −.76, P = 0.01). A similar correlation, in 12 subjects, was seen for p,p′-DDT (rs = −0.76, P = 0.01). The corresponding negative correlation, in 13 subjects, with blood levels of PCDD/Fs was not significant (rs = −0.57, P = 0.07). No significant association was seen between organic mercury in erythrocytes and NK cells. Fish consumption was not associated with levels of any other lymphocyte subset. Neither were there any correlations with plasma immunoglobulins or liver enzyme activities. Our study indicates that accumulation of persistent organochlorine compounds in high consumers of fatty fish may adversely affect NK cell levels.

Acidic deposition and human exposure to toxic metals.

Acid precipitation affects the solubility of several metals in aquatic systems and in soil. Cadmium levels in tap water samples from geological areas having low resistance to acidic pollution were significantly higher than those in samples from a neighbouring reference area where there was a different geological structure. The median cadmium levels and pH values were 0.14 microgram l-1 and 5.6 respectively, for the acidic areas compared with 0.07 microgram l-1 and 6.4 respectively for the reference area. Further, there was a significant inverse relationship between both cadmium and lead contents and the pH values of the samples. The mobility of the metals was thus dependent on the acidity. The blood lead levels in 195 subjects from the acidic areas were lower than those in 91 subjects from the reference area (medians 60 vs. 70 micrograms l-1); no significant differences were found in blood cadmium or blood mercury levels. Subjects in the acidic areas had lower plasma selenium levels than those from the reference area (medians 85 vs. 90 micrograms l-1); the difference was mainly attributed to subjects with private wells. The data may indicate a negative effect of the acidic pollution on selenium intake via water and/or foods. There was also a positive relationship between intake of fish on the one hand and blood mercury and plasma selenium on the other, which is in accordance with the role of fish as a source of these metals.

Effects of Lead on the Endocrine System in Lead Smelter Workers

Abstract In this study of the effects of lead on the endocrine system, 77 secondary lead-smelter workers (i.e., 62 active and 15 retired) were compared with 26 referents. Lead concentrations were determined in plasma with inductively coupled plasma mass spectrometry (i.e., index of recent exposure), in blood with atomic absorption spectrophotometry and in fingerbone with K x-ray fluorescence technique (i.e., index of long-term exposure). In addition, pituitary hormones were determined in serum by fluoroimmunoassay and thyroid hormones and testosterone in serum were determined with radioimmunoassay. Nine lead workers and 11 referents were challenged with gonadotrophin-releasing hormone and thyrotrophin-releasing hormone, followed by measurements of stimulated pituitary hormone levels in serum. Median levels of lead in plasma were 0.14 μg/dl (range = 0.04–3.7 μg/dl) in active lead workers, 0.08 μg/dl (range = 0.05–0.4 μg/dl) in retired lead workers and 0.03 μg/dl (range = 0.02–0.04 μg/dl) in referents (1 μg/dl = 48.3 nmol/l). Corresponding blood lead concentrations were 33.2 μg/dl (range = 8.3–93.2 μg/dl), 18.6 μg/dl (range = 10.4–49.7 μg/dl) and 4.1 μg/dl (range 0.8–6.2 μg/dl), respectively. Respective bone lead levels were 21 μg/gm (range = -13 to 99 μg/gm), 55 μg/gm (range = 3–88 μg/gm) and 2 μg/gm (range = -21 to 14 μg/gm). Concentrations of basal serum hormone (i.e., free thyroid hormones, thyrotrophin, sex hormone binding globulin and testosterone) were similar in the 3 groups. There were no significant associations between the hormones mentioned herein and blood plasma, blood lead and bone lead levels. In the challenge test, stimulated follicle-stimulating hormone levels were significantly lower in lead workers (p = .014) than in referents, indicating an effect of lead at the pituitary level. Also, there was a tendency toward lower basal stimulated follicle-stimulating hormone concentrations in lead workers (p = .08). This effect, however, was not associated with blood plasma level, blood lead level, or bone lead level. In conclusion, a moderate exposure to lead was associated with only minor changes in the male endocrine function, particularly affecting the hypothalamic-pituitary axis. Given that sperm parameters were not studied, the authors could not draw conclusions about fertility consequences.

Lead exposure in indoor firing ranges

SummaryHigher air lead levels (time-weighted average 660, range 112–2238 μg/m3) were measured in firing ranges where powder charges were employed than in ranges where air guns were used (4.6, range 1.8–7.2 μg/m3); levels in the latter were in turn higher than those in ranges used for archery (0.11, range 0.10–0.13 μg/m3) Twenty-two marksmen who used powder charges had significantly increased blood lead levels during the indoor shooting season (before: median 106, range 32–176 μg/l; after: 138; range 69–288 μg/l; P = 0.0001), while 21 subjects who mainly used air guns displayed no significant increase (before: median 91, range 47–179 μg/l; after: 84; range 20–222 μg/l). Thirteen archers had significantly lower levels than the pistol shooters before the season (P = 0.006), and showed a significant decrease during the season (before: median 61, range 27–92 μg/l; after: 56; range 31–87 μg/l; P = 0.04). At the end of the indoor season, there was a significant association between weekly pistol shooting time and blood lead levels.

High consumption of fatty fish from the Baltic Sea is associated with changes in human lymphocyte subset levels

Fatty fish from the Baltic Sea accumulate immunotoxic persistent organochlorine compounds. In a previous study we found inverse correlations between such fish consumption and natural killer (NK) cell levels in a Swedish population. The present study concerns 68 Latvian subjects with high, low or intermediate fish consumption. High fish consumption correlated positively with B cell levels and CD4+/CD8+ ratios, but negatively with levels of cytotoxic (CD8+) T cells. Furthermore, NK cell levels correlated inversely with plasma selenium, one of several strong correlates with fish intake. A high fish diet includes a set of possible immunomodulating agents. It is presently not possible to pinpoint the cause for the observed subset deviations or to establish their possible biological importance.