Toxic Chemicals, Potential

TOXIC CHEMICALS (potential chemical warfare agents)... 

The third of the major hazards and the one with the greatest disaster potential is the release of toxic chemicals. The hazard posed by toxic release depends not only on the chemical species but also on the conditions of exposure. The high disaster potential from toxic release arises in situations where large numbers of people are briefly exposed to high concentrations of toxic material, i.e., acute exposure. However, the long-term health risks associated with prolonged exposure at low concentrations, i.e., chronic exposure, also present serious hazards. 

The state of Texas controls chemical process ha2ards through its statute that estabUshed the Texas Air Control Board in 1965. In 1985, guidelines were estabUshed for evaluations of community impact of releases of 46 toxic chemicals, if Texas decides that a disaster potential exists (26). 

Toxic Substances Control Act. EPA regulates the manufacture, use, and exposure to ha2ardous or toxic chemicals under a number of laws. Eor the chemical industry, the law of prime concern is the Toxic Substance Control Act (TSCA) (10), which was passed by the U.S. Congress in 1976. The two main goals of TSCA are acquisition of sufficient information to identify and evaluate potential ha2ards from chemical substances, and regulation of the production, use, distribution, and disposal of these substances. 

Hazardous Air Pollutants. Tide 3 of the CAAA of 1990 addresses the release of hazardous air poUutants (HAPs) by requiring both the identification of major stationary sources and area source categories for 189 toxic chemicals and the promulgation of control standards. Major sources of air toxics, also referred to as HAPs, include any stationary source or group of sources emitting 10 or more tons/yr of any single Hsted toxic chemical or 25 tons/yr of a combination of any Hsted toxic. Area sources of HAPs include smaller plants that emit less than the 10 or 20 tons/yr thresholds. The major sources of HAPs are typically industrial faciHties. However, Tide 3 requites the EPA to study potential health affects associated with emissions of HAPs from electric UtiHty boilers (11). 

Potentiation is appHed to a condition where one material, of relatively low toxicity, enhances the expression of toxicity by another chemical. The result may be a larger response or more severe injury than that produced by the toxic chemical alone. A particular example is an enhancement of the absorption of a material of known toxicity by a surface-active material. 

The Toxic Substances Control Act (TSCA) was enacted in 1976 to identify and control toxic chemical ha2ards to human health and the environment. One of the main provisions of TSCA was to estabUsh and maintain an inventory of all chemicals in commerce in the United States for the purpose of regulating any of the chemicals that might pose an unreasonable risk to human health or the environment. An initial inventory of chemicals was estabhshed by requiring companies to report to the United States Environmental Protection Agency (USEPA) all substances that were imported, manufactured, processed, distributed, or disposed of in the United States. Over 50,000 chemical substances were reported. PoUowing this initial inventory, introduction of all new chemical substances requires a Premanufacturing Notification (PMN) process. To be included in the PMN are the identity of the new chemical, the estimated first year and maximum production volume, manufacture and process information, a description of proposed use, potential release to the environment, possible human exposure to the new substance, and any health or environmental test data available at the time of submission. In the 10 years that TSCA has been in effect, the USEPA has received over 10,000 PMNs and up to 10% of the submissions each year are for dyes (382)... 

Hazardous Substances Data Bank (HSDB) on compact disc from the Canadian Center for Occupational Health and Safety (can buy at CCOHS web site). "The HSDB(R) (Hazardous Substances Data Bank(R)) database contains data profiles on 4,500 potentially toxic chemical substances. It is created and updated by specialists at the U.S. National Library of Medicine. Compiled from an extensive range of authoritative sources, HSDB is widely recognized as a reliable and practical source of health and safety information. Much of the data is peer reviewed. 

Rockville Pike than 50,000 potentially toxic chemicals. Building 38A Source for basic acute and chronic toxicity... 

International Register of Potentially Toxic Chemicals (IRPTC)... 

Contains information drawn from data compiled by the National Toxicology Program (NTP), which coordinates and provides information about potentially toxic chemicals with potential for human exposure to regulatoiy and research agencies. Contains information on 2,280 chemicals drawn from literature. The records closely resemble an MSDSformat. Print, CD-ROM and online interactive versions available from the Coast Guard and commercial sources. 

Molecular structural analysis is a developing method. The objective of a molecuhu structural analysis is to demonstrate a physical, structural, or chemical similarity between tlie chemical in question and a known toxic chemical tliat produces toxic and healtli effects in experimental animals and/or humans. Unfortunately, scientists do not fully understand tlie effects of slight changes in tlie chemical structure and tlieir biological effect on humans. As a result, tills type of analysis is useful in preliminary studies to identify potential health hazards for further e. amination with more established metliods in short-tenii tests or tests in experimental animals, hi its present stage of development, molecular structural analysis caiuiot be used to make absolute decisions about tlie appropriate levels of exposure of humans to chemicals... 

Although NOT is not usually thought of as a "toxic" chemical, it does cause several health problems including methemoglobinemia in infants (blue-baby syndrome) and may also be linked to stomach cancer. Agricultural runoff can lead to significant, potentially harmful, concentrations of NOT in ground or surface water. 

Case-Control Study—A t5q)e of epidemiological study which examines the relationship between a particular outcome (disease or condition) and a variety of potential causative agents (such as toxic chemicals). In a case-controlled study, a group of people with a specified and well-defined outcome is identified and compared to a similar group of people without outcome. 

For each chemical class, a set of 4-7 key attributes were identified that can be used to differentiate a chemical from others in the same class. These may include biodegradability, aquatic toxicity, sensitization potential, renewable resource derived, and so forth. Each attribute was selected to be ... 

Section 313 of the Emergency Plarming and Commimity Right to Know Act (EPCRA) of 1986 was enacted to facilitate emergency planning, to minimize the effects of potential toxic chemical accidents, and to provide the pubhc with information on releases of toxic chemicals in their communities. The crurent fist contains 581 individually listed chemicals and 30 chemical categories. 

Congress amended CERCLA in 1986 with the enactment of the SARA. These amendments improved the Superfund program and added an important section that focused on strengthening the rights of citizens and communities in the face of potential hazardous substance emergencies. This section, SARA Title III, or the EPCRA, was enacted in response to the more than 2000 deaths caused by the release of a toxic chemical in Bhopal, India. 

Maximizing the use of existing information, including the reasons for producing a chemical and its uses, as well as knowledge of its toxic hazard potential. 

CCTTE. 1988. Computerized Listing of Chemicals Being Tested for Toxic Effects. United Nations Environment Programme, International Programme on Chemical Safety, International Register of Potentially Toxic Chemicals, Geneva, Switzerland. 

One of the most obvious benefits of plants is the potential for production scale up, leading to the production of virtually limitless amounts of recombinant antibody at minimal cost Plants are easy to grow, and unlike bacteria or animal cells their cultivation is straightforward and does not require specialist media, equipment or toxic chemicals. It has been estimated that plantibodies could be produced at a yield of 10-20 kg per acre at a fraction of the cost associated with production in mammalian cells [2,18] The use of plants also avoids many of the potential safety issues associated with other expression systems, such as contaminating mammalian viruses or prions, as well as ethical considerations involving the use of animals. 

In addition to its broad occurrence under contrasting conditions, easy collection, relatively long life span, and resistance to the accumulation of toxic chemicals, zebra mussels provide a link between the pelagic and benthic food webs, possibly creating a rapid pathway for contaminant transfer from sediments to predators such as common carp (Cyprinus carpio) and, occasionally, humans [32, 42—4-7]. Consequently, zebra mussel has been considered a potential sentinel organism for assessing Hg redistribution from point sources in the Ebro River and the degree of bioavailability to river and wetland food webs. 

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