Data gap

Given the enormous number of resources for chemical information available, many researchers do not have the time to learn the details of the variotis systems, and they end up searching in only a few resources with which they are familiar. This is a dangerous approach Knowing that both fee and non-fee resources are available on the Internet and both hold the desired information, it is prudent to search non-fee systems first and then use proprietary databases to fill data gaps [49]. 

Despite the plethora of data in the scientific literature on thermophysical quantities of substances and mixtures, many important data gaps exist. Predictive capabilities have been developed for problems such as vapor-liquid equihbrium properties, gas-phase and—less accmately—liquid-phase diffusivities, aud solubilities of uouelectrolytes. Yet there are many areas where improved predictive models would be of great value. Au accrrrate and rehable predictive model can obviate the need for costly, extensive experimental measurements of properties that are critical in chemical manufactming processes. 

Fourteen formulations of chemical alternatives were submitted to EPA under confidentiality and they were assessed based on numerous human health and ecotoxicity endpoints in addition to bioaccumulation potential and environmental persistence. They were also screened for potential exposure to workers, users and the aquatic environment. Where data gaps existed, EPA experts used models and chemical analogs to estimate the hazard for a particular endpoint. The literature and test data reviews were published in the final report, Environmentally Preferable Options for Furniture Fire Safety Low Density Furniture Foam . In addition, each hazard endpoint was ranked with a concern level (High, Moderate or Low) based on the criteria used by the EPA s New Chemicals Program to rate the concern level of new chemicals submitted under the Toxic Substance Control Act (TSCA). As seen in Figure 8.2, where the hazard endpoint rankings are bold, the value is based on experimental data. Where the hazard endpoints are presented in italic font, the value is estimated based on models or chemical analogs. In this way, detailed hazard information was summarized and presented in a clear and concise format. 

Substance-Specific Data Needs Related to Toxicological Profiles (ATSDR 1989), is substance-specific information necessary to conduct comprehensive public health assessments. Generally, ATSDR defines a data gap more broadly as any substance-specific information missing from the scientific literature. 

Interpretation of the results, which includes both the evaluation of the results in terms of the goal and scope as defined before and the assessment of the robustness of the results in terms of uncertainties and data gaps. 

To test the assumption whether additives indeed do not contribute to any significant amount to life cycle impacts of plastics, Van Oers and Van der Voet [1] conducted a case study on PVC flooring, appearing in this volume as well. They conclude that additives can indeed contribute to life cycle impacts, and therefore more attention should be paid to additives. Closing the data gaps therefore seems to be a very important issue. 

In a first attempt to derive characterization factors with QSARs, the entire dataset of plastics additives was included, and aquatic ecotoxicity was predicted for two different trophic levels. This generated characterization factors that did not correspond well with the ones derived from experimental data [30]. Hardly surprising, but a clear indication that two trophic levels are unsufficient. A second attempt to derive characterization factors with QSARs are currently being performed [31]. In this second attempt, substances that are difficult to model in QSAR models have been removed from the dataset and the ecotoxicity has been predicted for three different trophic levels instead of two. However, results have not yet been obtained from this second attempt. If the results show that it is possible to derive reliable characterization factors by the use of QSARs, the current data gap regarding characterization factors for human toxicity and ecotoxicity could be... 

The data gap could be solved conducting animal testing in rodents and other species which requires high cost and time thousands of animals are used to perform a complete set of regulatory tests for a single chemical and costs millions of dollars [2],... 

As emphasized above, two important workshops held in 2001 identified a number of data gaps and research needs to advance the state-of-the-science for assessing the potential for dit.161719 30 Moreover, participants in a 2003 roundtable discussion emphasized that a number of important research efforts are currently underway in the areas of DIT, examining immune system responses following developmental exposures to known immunotoxicants.38... 

An overview is provided of ongoing risk assessments on halogenated phosphate ester flame retardants in Europe. On the basis of the so-called second and fourth Priority lists on Existing Chemicals (Council Regulation No793/93) three chlorinated phosphate ester flame retardants are selected. The selection is based on their hazard profile, volume and use pattern. The three substances involved are TCPP, TDCP and TCEP (Antiblaze V6 from Albemarle is also involved but, due to confidentiality, is not discussed. An outline is provided from a European point of view on topics such as methodology of risk analyses, data-gaps and worst case approach, industry involvement, downstream participation and possible impact of final report on industry. 2 refs. 

In the U.S. it has become apparent that the number of materials which need to be considered for priority testing is such that, even after the screening approach described is applied and case-by-case selections are made, it will require our combined resources the next five to 10 years to adequately fill the data gaps so identified. 

At many sites, the investigation phase is performed in two tasks (Phase 1 and Phase 2). Phase 1 focuses on the large picture, a definition of overall site conditions. Data developed are used to assess potential risks and identify potential remedial options. Phase 2 work fills in data gaps and defines the level of detail necessary to establish site-specific remediation goals and to evaluate probable remediation procedures or to indicate the need for pilot cleanup studies. 

A search of the Federal Research in Progress database (FEDRIP 1994) indicates that the following research studies are in progress to fill in the data gaps discussed in Section 5.7.1. 

A search of federal research programs in progress indicates a few projects that would fill some of the existing data gaps. Drs. Singmaster and Acin-Diaz of the University of Puerto Rico are developing methods for determining disulfoton residue levels in food commodities and for disulfoton disposal. 

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