Basic toxicity information

The section on general toxicological and biological parameters reviews and summarizes chemical data and basic toxicity information available on the agent of interest and reviews data on absorption, distribution, metabolism, and excretion in humans and experimental animals. 

RTECS, compiled by NIOSH (U.S. National Institute for Occupational Safety and Health), is a comprehensive database of basic toxicity information and toxic-effects data on more than 100,000 chemicals. 

Of the approximately 80,000 chemicals that are in commercial use in the United States, even basic toxicity information is missing for nearly 75% of the top 3000 high production volume species. Essentially nothing is known about the toxicities of mixtures of these chemicals. 

The United States of America in 1998 announced the Chemical Right-to-Know (RTK) Initiative46 which was the US government response to an Environmental Protection Agency (EPA) study that found that very little basic toxicity information is publicly available on most of the HPV chemicals made and used in the USA. It should be noted that the US definition of UPV chemicals is different from that used in the rest of the world, as the US definition is a chemical produced in or imported into the US A in amounts... 

This very nseful regulation, after more than a qnarter century of practice does not give sufficient information. EPA has selected a group of High Production Volume, HPV, chemicals which constitutes 2,863 organic chemicals produced or imported at or above 1 million pounds per year in the United States. These chemicals have a large impact on health and safety becanse of their widespread application. EPA s analysis found that no basic toxicity information, i.e., neither hrrman health nor environmental toxicity, is publicly available for 43% of the high volume chemicals manufactured in the US and that a full set of basic toxicity information is available for only 7% of these chemicals. 

The lack of this basic toxicity information on most high volume chemicals is a serious issue for risk assessment, safeguarding children s health, expanding the publie s right-to-know, and promoting the pollution prevention ethic which are important EPA initiatives. 

While SDSs will list basic toxicity information, we know that the quality and reliability of these documents is suspect. Thus, we recommend two other sources of information that are more reliable ... 

Cefas Building, Assessing and Standardising Information on the Atlantic Coasts (BASIC) Toxicity Database... 

The BASIC toxicity database contains information on the aquatic toxicity of a number of hazardous substances. In many cases, the information is given as some sort of safe level such as UK Environmental Quality Standards (EQSs) or the national/international equivalent. For substances for which no such levels have been set, a brief literature review was performed in order to produce an environmental hazard/risk assessment. 

Group VI biomarkers have the same fundamental properties as those in group IV, so they also share basic uses. But group VI has another important attribute toxicity information is available. It could be the dose-response relationship with the parent chemical in animals or in humans or the rela-... 

Chemical data (e.g., physical and chemical properties, structureactivity relationships, and environmental fate and transport), basic toxicity data, and pharmacokinetic data (information on absorption, distribution (including placental and lactational transfer), metabolism, and excretion) should be reviewed. These data are particularly important because reproductive and developmental effects are interpreted in the context of general toxicity data in humans or experimental animals. Pharmacokinetic data for both animals and humans can be helpful in extrapolating exposure levels from one species to another. 

Source for basic acute and chronic toxicity information. Prime-time cost is about SS per hour. 

An example of a read across table of information is shown below. Substances Xi, X2, X3, X4, X5, Xg, X7, and Xg are structurally similar substances. For this example, the main structure could be CH3-Cj -CH3, with the only difference being the length of the C section of the molecule. Xi would be one carbon, X2 would be two carbons, etc., and thus X2 and X4 would be the closest in structure to X3, and X4 and Xg would be the closest in structure to X5. Note that acute oral toxicity data have been identified for X3 and X4, while X5 is supported by read across from X4 to Xg, with data also identified for Xj and Xg. For the in vivo genetic toxicity (i.e., micronucleus test), no data are available for X3, X4, and X5 however, these substances are supported by read across from X2 to Xg with data also available for Xj and Xg. Analysis of these data sets might lead to a judgment that a basic level of acute, genetic, repeat dose, and reproductive toxicity information is available for all of these substances, either directly or by read across to the other structurally similar substances. 

Sub-chronic and/or chronic toxicity study Additional mutagenicity screening studies Basic toxicokinetic information... 

QRA is fundamentally different from many other chemical engineering activities (e.g., chemistry, heat transfer, reaction kinetics) whose basic property data are theoretically deterministic. For example, the physical properties of a substance for a specific application can often be established experimentally. But some of the basic property data used to calculate risk estimates are probabilistic variables with no fixed values. Some of the key elements of risk, such as the statistically expected frequency of an accident and the statistically expected consequences of exposure to a toxic gas, must be determined using these probabilistic variables. QRA is an approach for estimating the risk of chemical operations using the probabilistic information. And it is a fundamentally different approach from those used in many other engineering activities because interpreting the results of a QRA requires an increased sensitivity to uncertainties that arise primarily from the probabilistic character of the data. 

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