Frutos secos: datos de consumo y perfil nutricional

4.5.1 Insufficient Denominator Data

Perhaps the biggest limitation of the existing accident databases to perform package performance studies to estimate the conditional probability of release for bulk packages is insufficient understanding of the denominator data. In other words, how often are packages exposed to various accident conditions in which they might fail? Detailed damage

information is needed for packages in accidents whether or not a release took place. Beginning in 2005, the restructured HMIRS requires non-release accidents to be reported if they involve a cargo tank with a minimum 10,000-gallon capacity and the lading retention system is damaged. These are classified as type C records, as opposed to type A

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for release incidents and type B for undeclared hazardous material shipment. HMCRP Report 1 (Battelle Memorial Institute 2009) suggests that there may be significant underreporting involving type C records, based on comparisons between HMIRS and MCMIS and TIFA. Substantial improvement to HMIRS for package performance statistical studies would be achieved if type C record underreporting could be reduced or eliminated. Underreporting could be reduced by cross-checking accident records in HMIRS with the list of (1) hazardous material fatal accidents in TIFA, (2) rollover accidents involving cargo tanks in MCMIS, and (3) repaired cargo tanks by auditing hazardous-material-authorized repair shops. Periodic audits would increase the number of incidents being reported and result in better statistical analyses.

4.5.2 Accident Underreporting

Underreporting is a term to describe the discrepancy between the total number of reportable incidents and the number of incidents actually reported. In HMCRP Report 1, Battelle (2009) sought to “bound the probable HMIRS reporting rate” by comparing

HMIRS reports resulting in a fatality with FARS records involving vehicles transporting bulk quantities of hazardous materials. Bulk hazardous materials accidents resulting in a fatality were found to be reported between 26.9 percent and 59.7 percent of the time. Since a Form DOT F 5800.1 is only required to be filed if the fatality is related to the release of hazardous materials, the FARS data comparison is not a direct indication of underreporting.

To further quantify the amount of underreporting for all crashes resulting in damage to the lading retention system, PHMSA HMIRS records between March 1, 2011 and

September 30, 2011 were matched to FMCSA MCMIS crash files and a news article dataset primarily using location date and description of events. During this period, PHMSA HMIRS database contained 123 reports of accidents of which 98 resulting in lading loss. FMCSA MCMIS crash files contained 754 reports of which 95 resulted in lading loss. It should be noted that not all 754 accidents resulted in damage to the lading retention system; however, at least 95 records (those resulting in lading loss) correspond to accidents in which the bulk package was damaged. The news article dataset was developed using news-source reported crashes identified through Google News Alert service. It included fields for date, time, location, state, and a description of what events occurred and consequences of those events, whether the bulk package overturned, and whether a release occurred. Between March 1,

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2011 and September 30, 2011, 127 hazardous materials bulk package accidents were identified in news sources. Of these 127 accidents, 103 resulted in lading loss. The combined dataset consisted of 924 accidents (Figure 4.2) of which 236 resulted in a release (Figure 4.3). This corresponds to an accident rate of 132 per month, of which 34 result in a release.

Figure 4.2 Venn Diagram of Hazmat Accidents

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Since not all of the FMCSA MCMIS records are of accidents that resulted in damage to the lading retention system, the combined dataset serves to identify the limits of

underreporting. The lower bound considers only those FMCSA accidents in which a release occurred (all release accidents are required to be reported to PHMSA). Of the 278 records in which damage to the bulk package is confirmed, 155 accidents were not reported to PHMSA. This corresponds to an underreporting rate of 56 percent. The upper bound considers all FMCSA crash data involving a hazardous materials bulk package even though reporting all of these accidents may not be required. Of these 924 accidents, 801 are not reported to PHMSA. If all 924 accidents resulted in damage to the bulk package, the underreporting rate would be 87 percent. Therefore, between 13 and 44 percent of accidents in which a bulk package was damaged are reported to PHMSA.

4.5.3 Poor Quality of Reported Information

The reports submitted to PHMSA HMIRS have varying degrees of completeness and response consistency. Battelle’s analysis of the HMIRS data showed that “some obvious Q/A checks are not being performed” (Battelle Memorial Institute, 2009). A brief analysis of the accidents reported to PHMSA from January 1, 2006 to June 4, 2011 was undertaken to identify the percentage of accident reports that result in poor quality data (Table 4.1). A total of 1,176 incidents were reported. Of these, the type of bulk container was identified for 997 (85 percent) incidents. A description of what failed was identified for 961 (82 percent) incidents. Reporting rates for bulk package design parameters such as package capacity, package amount, material of construction, design pressure, shell thickness and head thickness range between 67 percent and 45 percent. Finally, a comparison of the number of reported incidents satisfying PHMSA’s classification of a serious bulk release was compared to the number of incidents for which damages over $500 are reported. This analysis

indicated that the cost of damages was incorrectly reported for at least 38 (3 percent) serious bulk releases. Data checking and greater reporting compliance would result in better

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Table 4.1 Critical Fields Percent Reported for Incidents in PHMSA HMIRS from January 1, 2006 to June 4, 2011 Field Number of Incidents Percent of Total Number of Incidents

Total Number of Reported Incidents 1,176 --

Container Specification/Non-Specification Container 997 85%

What Failed 961 82% Package Capacity 745 63% Package Amount 709 60% Material of Construction 784 67% Design Pressure 623 53% Shell Thickness 543 46% Head Thickness 528 45%

Note: “--“ indicates this value is not applicable.