Tissue action level

Tissue action level - link sediment concentration to safe tissue concentration (e.g., FDA action level or body burden-response data) through application of equilibrium or kinetic models (numerical criterion). 

Data are scarce in mammals that link zinc concentrations in tissues with environmental zinc perturbations. In harbor porpoises, impaired homeostasis reportedly occurs when zinc exceeds 100 mg/kg FW liver however, livers of many species of marine mammals routinely exceed this value (Wood and Van Vleet 1996). Elevated zinc concentrations, in mg Zn/kg DW tissue, were >120 in cattle liver, >180 in sheep kidney, and >250 in sheep liver (Table 9.9), but their significance is unclear. No international regulations or guidelines applicable to zinc are available (USPHS 1989). No U.S. Food and Drug Administration action level or other maximum acceptable concentration exists for zinc, and therefore no Final Residue Value can be calculated (USEPA 1987). This seems to be a high priority research need. 

The Food and Drug Administration set an action level of 0.1 ppm mirex in fish tissue (EPA 1978a). 

M2a. Marks, P. A., Gross, R. T., and Hurwitz, R. E., Gene action in erythrocyte deficiency of glucose-6-phosphate dehydrogenase Tissue-enzyme levels. Nature (.London) 183, 1266-1267 (1959). 

Official U.S. and Canadian tolerance values are 50-300 yu-g/kg for SPI and 100-500 yttg/kg for TYL in milk and different tissues from various species (122). Action levels for TLM have been established by Agriculture Canada for cattle tissues 800 yu-g/kg in muscle and 2.4 mg/kg in kidney (123) and by FDA, 100 yu-g/L in milk (124). 

A summary of the mean, minimum, and maximum tissue concentrations of mercury detected for two of the sampled species with the widest geographical distribution the largemouth bass and the channel catfish are given in Tables 5-8 and 5-9. As Table 5-8 shows, the maximum mercury residues reported for the largemouth bass exceeded the FDA action level (1 ppm) in 15 of the 25 states that collected and analyzed tissue samples for this species. The highest maximum mercury concentration reported for this species was 4.36 ppm, reported by Florida. Table 5-9 shows the maximum mercury residue reported for another widely distributed species, the channel catfish. While the maximum mercury residues reported for this species are not consistently as high as those for the largemouth bass, maximum residues in... 

Tissue concentrations shown in bold type exceed the FDA action level of 1 ppm... 

The Food and Drug Administration (FDA) develops standards for radioactive material concentrations in food (FDA 1998), and medical devices used in radiation therapy (FDA 1997). The FDA recently updated its guidance document that presents recommended action levels for radionuclides in foods, both domestic and imported (FDA 1998). These derived intervention levels (DILs) are estimated levels in food that could lead to individuals receiving a radiation equivalent dose equal to the FDA protection action guide (PAG) that is set as the more limiting of either 0.5 rem (5 mSv) for committed effective dose or 5 rem (50 mSv) committed dose equivalent to any individual tissue or organ. Table 8-2 presents the most restrictive DILs for strontium. 

Ribel-Madsen, R., Eriedrichsen, M., Vaag, A. et al. 2009. Retinol-binding protein 4 in twins. Regulatory mechanisms and impact of circulating and tissue expression levels on insulin secretion and action. Diabetes 58 54—60. 

Endocrine In patients receiving the minimum dose of amiodarone, thyroid abnormalities were observed at a rate between 14% and 18%. The effects on the thyroid gland are variable. Amiodarone may cause abnormal thyroid function detected only by laboratory test as well as clinically manifested thyroid dysfunction. The mechanism of this adverse effect is complex. Amiodarone inhibits the action of deiodinase and decreases peripheral conversion of thyroid hormones. Moreover, it decreases their renal elimination and inhibits their entry to peripheral tissues. The level of T4 increases by 40% within 1-4 months of amiodarone therapy. The deiodinase activity inhibition can be noticed after 3 months of treatment. It leads to an increase in the level of thyroid stimulating hormones. Amiodarone and its metabolite have a direct cytotoxic effect on thyroid follicular cells, which results in destructive thyroiditis. Amiodarone-induced thyroid damage can lead either to hypo- or hyperthyroidism. The latter can be of two types. Type 1 usually occurs in patients with prior thyroid damage. In this type, iodine excess causes excessive synthesis of thyroid hormones whereas in type 2 the inflammatory process is followed by destruction. A destructive thyroiditis leads to the release of hormones from damaged thyroid follicular cells. This mechanism occurs in patients with no history of thyroid disorders [15]. 

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