Release of corrosion products from amalgam in phosphate containing solutions

Abstract— The effect of phosphate concentration on corrosion was compared for two types of amalgam: a conventional alloy (ANA 68) and a high-Cu admixed alloy (Dispersalloy). The test specimens were stored for 4 months in electrolytes containing 85 mM NaCl and 85 mM NaCl with 2.5, 10, or 100 mM phosphate buffer respectively. The solutions were renewed each month and analyzed for Cu, Zn, Sn, Hg, and Ag in an atomic absorption spectrophotometer. The surfaces and cross-sections of the specimens were studied in a scanning electron microscope (SEM) with an energy dispersive detector (EDAX). The corrosion products, mainly Sn-compounds, at the surface of the amalgams were less in the solutions containing high concentrations of phosphate. In cross-section subsurface corrosion of the high-Cu amalgam was observed especially in specimens immersed in the NaCl solution without phosphate. The conventional amalgam showed surface corrosion only. The decrease in release of elements with time from the conventional amalgam in all the experimental solutions might indicate passivation. For the high-Cu amalgam the release of elements increased with time, except for Cu and Sn in the solution with 100 mM phosphate, indicating that phosphate inhibits corrosion of the Cu-Sn-phases. Release of corrosion products from the high-Cu amalgam was more dependent on the presence of phosphate than the conventional amalgam.     

Immune modulation by cadmium and lead in the acute reporter antigen-popliteal lymph node assay.

Immune modulation by heavy metals may cause serious adverse health effects in humans, although the mechanisms involved are not well understood. Both cadmium and lead are important environmental and occupational toxins. Therefore, in the current study, the costimulatory/adjuvant effects and the T-cell-activating potential of these metals (i.e., CdCl2 and PbCl2), are examined. These immune-modulating properties are critical in the development of conditions such as allergy, hypersensitivity, and autoimmunity. Using the direct popliteal lymph node assay (PLNA) and reporter antigen-popliteal lymph node assay (RA-PLNA) both metals were examined individually for immunotoxicity. Mercury (i.e., HgCl2) was included for comparative purposes as its effects in the RA-PLNA are well documented. Seven days following a single footpad injection containing metal and/or RA (trinitrophenyl-ovalbumin [TNP-OVA] or TNP-Ficoll), BALB/c mice were sacrificed and the popliteal lymph nodes (PLNs) removed. PLN cellularity, TNP-specific antibody-secreting cells (ASCs), and lymphocyte subsets were assessed. All three metals strongly stimulated T- and B-cell proliferation and ASC production following coinjection with the RA TNP-OVA. In each case, ASC production was skewed towards the IgG1 isotype. In addition, all three metals induced IgG production to TNP-Ficoll (although relatively weakly in the case of Cd). These results show that each of these metals can provide adjuvant signals to promote lymphocyte proliferation and enhance adaptive immune responses to unrelated antigens. Skewing of immune responses towards T helper type 2 responses suggests that each of these metals can enhance allergic and hypersensitivity reactions to environmental antigens. Furthermore, the induction of IgG responses to TNP-Ficoll, a T-cell-independent antigen, indicates that each of these metals can activate neoantigen-specific T cells. T-cell activation by metals can lead to metal hypersensitivity and has been implicated in the development of autoimmunity. This is the first report of immune modulation by CdCl2 and PbCl2 in the RA-PLNA.     

Assessment of metallothionein and antibodies to metallothionein in normal and autistic children having exposure to vaccine-derived thimerosal

Allergic autoimmune reaction after exposure to heavy metals such as mercury may play a causal role in autism, a developmental disorder of the central nervous system. As metallothionein (MT) is the primary metal-detoxifying protein in the body, we conducted a study of the MT protein and antibodies to metallothionein (anti-MT) in normal and autistic children whose exposure to mercury was only from thimerosal-containing vaccines. Laboratory analysis by immunoassays revealed that the serum level of MT did not significantly differ between normal and autistic children. Furthermore, autistic children harboured normal levels of anti-MT, including antibodies to isoform MT-I (anti-MT-I) and MT-II (anti-MT-II), without any significant difference between normal and autistic children. Our findings indicate that because autistic children have a normal profile of MT and anti-MT, the mercury-induced autoimmunity to MT may not be implicated in the pathogenesis of autism.     

松花江同江江段渔民发汞值调查

本文对松花江同江江段沿江渔民于1990年4月进行头发总汞值调查。调查结果,渔民发汞值中位数为2.574ppm。处于受汞污染状态,即4ppm以上者仅占24.46％。没有超过10ppm者。     

松花江汞污染治理后沿江渔民发汞调查

调查结果表明，沿江渔民发汞均值为２．２５μｇ／ｇ，与对照点相比差异显著（Ｐ＜０．０１），其中扶余一松江段渔民发汞均值２．５４μｇ／ｇ，高于其他各江段；３０～４０岁年龄组渔民发汞值超过正常值者占４５％，比其他各年龄组多；在调查的１１９５人中有２５名发汞值超过１０μｇ／ｇ，其中１８人发甲基汞含量超过５μｇ／ｇ。     

汞对人体必需元素干扰的研究

对42例汞吸收、2例汞中毒者(尿汞>99.7nmol/L),采用原子吸收光谱法,检测了汞对人体必需五种金属元素代谢的干扰。研究发现,汞时人体必需元素镁、铜具有拮抗作用。汞吸收者血清镁极显著低于对照组(P>0.01)。经驱汞治疗后,血清镁、铜自然上升与对照组无统计学差异(P>0.05),镁离子低下,可出现神经肌纤维兴奋性增高。由此推测,汞引起肌肉震颤的毒理,可能由汞拮抗镁离子低下引起。设想,对汞中毒者采用补镁制剂治疗,是否具有驱汞作用值得探讨。     

接触金属汞的工人淋巴细胞微核率和姊妹染色单体互换率的观察

用机械法可使菜籽粕中毒性质的丙基异硫氰酸酯由０．７１％降到０．２１％，脱除率为７０．４２％，可替代猪、鸡中部分豆饼、鱼粉、降低饲料成本９．５６％－１２．６９％，县地生产性能不良影响。这种脱毒菜籽粕在体重３５－６０ｋｇ阶段猪日粮中用量不宜超过２０％；在肉仔鸡日糖中用量可为１０％或１５％。     

小剂量氯化汞对小鼠脂质过氧化物的影响

本观察小剂量１ｍｇ／ｋｇ）ＨｇＣｌ２对小鼠肝，脑组织中脂质过氧化物（ＬＰＯ）的影响，发现小剂量ＨｇＣｌ２可使肝组织中ＬＰＯ含量明显增高，与对照组比，差异有显性（Ｐ〈０．０２５），而脑组织中ＬＰＯ含量未见明显影响（Ｐ〉０．０５）。     

接触汞对男工生殖功能影响的调查研究

本文选择接触汞男工１１７名，对照组１２３名对他们的性功能、男工妻子妊娠的结局、胎儿发育和子代生长状况进行了回顾性调查。接触汞男工的阳萎、早泄和性减退率明显增高，每周的性交次数明显减少，与对照组比较均有显著性差异（Ｐ＜０．０５），男工妻子的早产、自然流产、难产和围产儿死亡率高于对照组。本文调查结果说明无机汞可能引起男性功能障碍。     

Subclinical neurotoxicity of mercury vapor revealed by a multimodality evoked potential study of chloralkali workers

Pattern visual, brainstem auditory, and somatosensory evoked potential (EP) studies were performed on 26 chloralkali workers. The intensity of mercury vapor exposure in these workers was estimated from the individual working history. Mercury levels in blood, urine, and hair were determined with atomic absorption spectrometry. The EP findings were compared with those from individually matched normal subjects. In brainstem auditory and somatosensory EP studies, prolonged neural conduction times in the central nervous system (CNS) were found in workers exposed to mercury vapor. In the pattern visual EP study, mercury workers had higher interpeak amplitudes. Findings of this study suggested that chronic exposure to mercury vapor would affect the CNS functions. A multimodality EP study is a useful adjunct in evaluation of chronic mercury neurotoxicity, especially in an epidemiological study.