Occupational settings selection

L. Hagmar, T. Bellander, J. Ranstam and S. Skerfving, Piperazine-induced airways symptoms Exposure-response relationships and selection in an occupational setting. Am. J. Ind. Med., 1984, 6, 347-357. 

The expectancy fi that a cell ( ) is occupied by a segment of a preceding molecule when vacancy of an adjoining cell (f—1) has been established beforehand in the course of seeking out the sets of x contiguous lattice cells available to molecule +1, is not exactly equal to the average expectancy fi of occupation of a cell selected at random. This latter expectancy is, of course, equal to the fraction of all cells in the lattice which are occupied by segments of the i molecules or... 

The studies involved determining appropriate environmental pathways that would result in exposure to humans, determining appropriate occupancy factors (number and distribution) within structures, characterizing the source term for each property, selecting an appropriate set of health risk coefficients, calculating health effects, and providing summary reports of potential health effects for each vicinity property. 

There are no occupational exposure limits for many hazardous substances which may require control of inhalation exposures. The necessary data and other resources required for setting such limits is restricted and unlikely to match the potential demand. A hazard categorisation scheme was, therefore, developed for application within the chemical industry. The scheme used readily-available information on toxicological endpoints to place hazardous substances into a limited range of hazard categories, expressed as Occupational Exposure Bands. These Bands could be used as a basis for risk assessment and the selection of appropriate control regimes. 10 refs. EUROPEAN COMMUNITY EUROPEAN UNION UK WESTERN EUROPE... 

These results were obtained by coupling a genetic algorithm for descriptor and calculation parameter (PC, bins) selection to PCA-based partitioning. In these calculations, descriptors were chosen from a pool of approx 150 different ones, and both the number of PCs and bins were allowed to vary from 1 to 15. An initial population of 300 chromosomes was randomly generated with initial bit occupancy of approx 15%. Rates for mutation and crossover operations were set to 5% and 25%, respectively. After PCA-based partitioning, scores were calculated for the following fitness function ... 

As the first test case, we selected 20 aliphatic primary amines from a set of 493 commercially available ones by three different methods random reagent selection, entropy-optimised ProSAR selection and an occupancy-optimised method which purely maximises the occupancy of pharmacophore bins (56), i.e. ensures that as many bins as possible are covered by the reagent selection regardless of the pharmacophore distribution. As the greedy algorithm... 

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