Background: Concerns for arsenic exposure are not limited to toxic waste sites and massive poisoning events. Chronic exposure continues to be a major public health problem worldwide, affecting hundreds of millions of persons.Objectives: We reviewed recent information on worldwide concerns for arsenic exposures and public health to heighten awareness of the current scope of arsenic exposure and health outcomes and the importance of reducing exposure, particularly during pregnancy and early life.Methods: We synthesized the large body of current research pertaining to arsenic exposure and health outcomes with an emphasis on recent publications.Discussion: Locations of high arsenic exposure via drinking water span from Bangladesh, Chile, and Taiwan to the United States. The U.S. Environmental Protection Agency maximum contaminant level (MCL) in drinking water is 10 µg/L; however, concentrations of > 3,000 µg/L have been found in wells in the United States. In addition, exposure through diet is of growing concern. Knowledge of the scope of arsenic-associated health effects has broadened; arsenic leaves essentially no bodily system untouched. Arsenic is a known carcinogen associated with skin, lung, bladder, kidney, and liver cancer. Dermatological, developmental, neurological, respiratory, cardiovascular, immunological, and endocrine effects are also evident. Most remarkably, early-life exposure may be related to increased risks for several types of cancer and other diseases during adulthood.Conclusions: These data call for heightened awareness of arsenic-related pathologies in broader contexts than previously perceived. Testing foods and drinking water for arsenic, including individual private wells, should be a top priority to reduce exposure, particularly for pregnant women and children, given the potential for life-long effects of developmental exposure.

Four widely used in vitro assays for genetic toxicity were evaluated for their ability to predict the carcinogenicity of selected chemicals in rodents. These assays were mutagenesis in Salmonella and mouse lymphoma cells and chromosome aberrations and sister chromatid exchanges in Chinese hamster ovary cells. Seventy-three chemicals recently tested in 2-year carcinogenicity studies conducted by the National Cancer Institute and the National Toxicology Program were used in this evaluation. Test results from the four in vitro assays did not show significant differences in individual concordance with the rodent carcinogenicity results; the concordance of each assay was approximately 60 percent. Within the limits of this study there was no evidence of complementarity among the four assays, and no battery of tests constructed from these assays improved substantially on the overall performance of the Salmonella assay. The in vitro assays which represented a range of three cell types and four end points did show substantial agreement among themselves, indicating that chemicals positive in one in vitro assay tended to be positive in the other in vitro assays.

Results from the testing of 108 coded chemicals in Chinese hamster ovary (CHO) cells for the induction of chromosome aberrations and sister chromatid exchanges (SCEs) are presented. All chemicals were tested with and without exogenous metabolic activation, using protocols designed to allow testing up to toxic doses. Cell harvest times could also be extended if chemical-induced cell cycle delay was seen. Chromosome aberrations were induced by 43 of the chemicals, and 66 induced SCEs; 37 of the chemicals were positive for both endpoints.

311 chemicals were tested under code, for mutagenicity, in Salmonella typhimurium; 35 of the chemicals were tested more than once in the same or different laboratories. The tests were conducted using a preincubation protocol in the absence of exogenous metabolic activation, and in the presence of liver S-9 from Aroclor-induced male Sprague-Dawley rats and Syrian hamsters. Some of the volatile chemicals were also tested in desiccators. A total of 120 chemicals were mutagenic or weakly mutagenic, 3 were judged questionable, and 172 were non-mutagenic. The remaining 16 chemicals produced different responses in the two or three laboratories in which they were tested. The results and data from these tests are presented.

Three hundred chemicals were tested for mutagenicity, under code, in Salmonella typhimurium, using a preincubation protocol. All tests were performed in the absence of exogenous metabolic activation, and in the presence of liver S-9 from Aroclor-induced male Sprague-Dawley rats and Syrian hamsters. The results and data from these tests are presented.

The results and data from the testing of 255 chemicals for mutagenicity in Salmonella are presented. All chemicals were tested under code using a preincubation modification of the Sulmonellalmicrosome test in the absence of exogenous metabolic activation and in the presence of liver S-9 from Aroclor-induced male Sprague-Dawley rats and Syrian hamsters. Key words: metabolic activation, Ames test, National Toxicology Program INTRODUCTIONA number of in vitro and in vivo test systems are being used in the National Toxicology Program (NTP) to evaluate chemicals for their ability to induce mutations , chromosome damage, and DNA damage. The rationale for testing has been described in detail elsewhere [Zeiger and Drake, 19801. The purpose of this report is to present the results and data from the testing of 255 chemicals for their ability to induce mutations in Salmonella. Because some chemicals were tested in more than one laboratory or at different times within the same laboratory, a total of 291 individual samples were tested. MATERIALS AND METHODS ChemicalsThe chemicals tested, their sources, and purities (where known) are listed in Table I; the chemical structures are presented in Appendix 1. The laboratories were supplied with the chemicals, which were coded by the NTP chemical repository (Radian Corp., Austin, TX), along with information on the physical characteristics of the chemicals, their solubility in different solvents, and safety and decontamination information. Also supplied, but in sealed envelopes, was information on the identity and toxicity of the chemicals. This was to be used in the event of a spill or personnel exposure. All coded chemicals were handled as potential mutagens and carcinogens.A number of chemicals were tested in more than one laboratory or at different times in the same laboratory. When this occurred, the laboratory performing the retest was not informed of the identity of the chemical or that it had been tested previously.The solvent of choice was distilled water, followed by dimethyl sulfoxide, 95% ethanol, and acetone. The individual laboratories made independent assessments of the solvents to be used. Bacterial StrainsAll chemicals were tested in Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537 and/or TA97. The majority of chemicals were tested in TA1537, and a few were tested in TA97. The testing in both strains is the result of an evolution of the protocol described by Haworth et a1 [1983]. In this original protocol, TA1537 was used. In a later protocol, TA97 replaced TA1537, but the option to retest a chemical in TA1537 was retained for chemicals that produced a positive or questionable response in TA97 and negative responses in the other strains.All strains were obtained from Dr. Bruce Ames (University of California, Berkeley) and were stored as recommended [Maron and Ames, 19831. Prior to their use for mutagenicity assays, all cultures were grown overnight with shaking at 37°C in Oxoid broth, and their phenotypes were analyzed, Preparation of Liver S-9 Fraction...

The results and data from the testing of 255 chemicals for mutagenicity in Salmonella are presented. All chemicals were tested under code using a preincubation modification of the Salmonella/microsome test in the absence of exogenous metabolic activation and in the presence of liver S-9 from Aroclor-induced male Sprague-Dawley rats and Syrian hamsters.

Since its launch in February 2004, Facebook has become one of the most popular websites in the world, as well as a widely discussed media phenomenon. Unsurprisingly, the Facebook revolution has inspired a wealth of psychological study, which is growing exponentially. In this article, we review the recent empirical research into some of the key psychological themes concerning Facebook use. The review is organized according to common questions about Facebook culture and use being posed by academics and social commentators alike. These questions are grouped under three major themes, namely: (a) antecedents of Facebook use; (b) how individuals and corporations use Facebook; and (c) psychological outcomes or effects of Facebook use. To this end, we review over 100 recent publications (mostly empirical, peer-reviewed journal articles). We conclude by providing some suggestions for future psychological research in this rapidly expanding area of popular media culture.