| An Evaluation of the Hazards of Toys and other Products made from Polyvinyl Chloride (PVC) |
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| An Evaluation of the Hazards of Toys and other Products made from Polyvinyl Chloride (PVC) |
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New article, July 2000: Communication From Dr. Joseph DiGangi: To my knowledge, the organotin content of toys has not been studied. Organotins were substituted for lead when vinyl miniblinds were formulated. Some additional toxic effects of organotins are as follows: [Organotin] Chemical in Boat Paint, Household Items Blocks Cancer-Fighting Cells ANAHEIM, California, March 24, 1999 (ENS) Anti-fouling paints used on boat hulls, wood preservatives, even common household items such as cellophane wraps and dish sponges have been found to contain a chemical compound that disrupts the function of human natural killer cells. The job of these blood cells is to destroy tumor cells and cells infected with viruses. Kentucky researchers have demonstrated, for the first time, that a class of common chemical contaminants known as butyltins disrupt the function of critical human immune cells. The scientists say biologically significant concentrations of butyltins were found in random human blood samples. This information was presented Wednesday evening at a national meeting of the American Chemical Society, the world's largest scientific society. Murray State University chemist Bommanna Loganathan, Ph.D. performed the study with another Murray State chemist, Margaret Whalen, Ph.D. Loganathan says this current study, using blood cells from adult male and female volunteers, is the first to demonstrate the effect of butyltin compounds on human immune cell function. Butyltin compounds come in either single, double, or triple forms. They are used to inhibit the growth of unwanted organisms such as bacteria, algae, and barnacles. At shipyards such as this large quantities of tributyltin paints are applied to vessels daily. Tributyltin (TBT) is used as a wood preservative as well as on fish culture nets, docks, and boat hull paints. Though TBTs have been banned on small boats for about a decade, they are still commonly used on large ships to prevent the growth of marine organisms. TBTs have been detected in seafood, such as fish and oysters collected from coastal areas, and in dolphin carcasses and seabed sediments. This study, however, is the first to focus on the effect of TBTs on the tumor-killing cells of humans. Other recent studies have suggested that tributyltin levels have decreased in U.S. waters in recent years, and some studies suggest that seafood does not contain enough tributyltins to cause human health problems. However, Murray State chemists say statistics for production of butyltins used in many everyday applications are not available. According to the Extension Toxicology Network maintained by Cornell University, Michigan State University, Oregon State University, and University of California at Davis, TBT by itself is unstable and will break down in the environment unless it is combined with an element such as oxygen. One of the most common TBT compounds is bis(tributyltin) oxide, or TBTO. This form has been the subject of most TBT testing. Other TBT compounds are used as disinfectants, fungicidal wood preservatives, textile disinfectants, and stabilizers in PVC resin. Paper and pulp mills, cooling towers, breweries, textile mills and leather-processing facilities may also use some forms of TBT. When exposed to "environmentally relevant" concentrations of tributyltin in the lab for as little as an hour, Loganathan says the tumor-killing ability of natural killer cells was inhibited. Mono and di-butyltins were found to be only slightly less harmful to the natural killer cells. Loganathan and Whalen say that mono and dibutyltins are found in a variety of household products including some types of diaper covers, sanitary napkins, shower curtains, gloves, cellophane wraps, dish sponges, wines, fruit juices, and poultry. Loganathan and Whalen note that the human body can degrade butyltins fairly efficiently and eliminates them in 24 to 48 hours. But, previous studies in rats have shown butyltins to have various toxic effects, including disruption of the immune system. The researchers also measured butyltin levels in the blood of eight people who Loganathan says should have had no extraordinary exposure to butyltins. He says he found "concentrations, in some cases, approaching levels where we saw inhibitory effects on natural killer cell cytotoxic function in the lab." Seventy percent of the world fleet of ships uses a tributyltin paint system, and there is a constant but very low release of TBT from the ship hulls. But this source of tributyltins may be phased out shortly. The International Maritime Organization is planning a global ban on the use of marine anti-fouling paints containing tributyltin from 2003. The International Maritime Organization (IMO), with 156 governments as members, is a specialized agency of the United Nations responsible for measures to improve the safety of international shipping and to prevent marine pollution from ships. The IMO's Marine Environment Protection Committee is currently drafting regulations to prevent the harmful effects of the use of anti-fouling paints, in particular those continuing tributyl tin. The IMO aims to hold a conference in the year 2000 to adopt the protocol. Alternatives exist. Treeline Wood Products Ltd. of Alberta, Canada uses a borate-based process for wood preservation. Borates are effective pesticide, fungicide and fire retardants and the company says they are "non-toxic to humans, animals and the environment." In marine paints, a new generation of biocides allow antifouling paints to protect ship bottoms from accumulating organisms while reducing environmental effects. Specialty chemicals manufacturer Rohm and Haas Company based in Philadelphia, Pennsylvania, is one company that has developed an alternative to tributyltin in marine paints for large commercial vessels. SEA-NINE® 211 marine antifoulant employs isothiazolone chemistry as a more environmentally acceptable ingredient in marine paints. The new marine antifouling agent was rewarded with the "Green Chemistry Challenge Award" from the U.S. Environmental Protection Agency in 1996. © Environment News Service (ENS)
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