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Soil at a former land treatment facility for waste oils and solvents was intensively studied using two different methods to determine if volatile organic compounds (VOC) were present. The results showed that on-site VOC concentrations obtained using heated headspace'gas chromatography were approximately 10 times higher than off-site VOC measurements obtained using purge-and-trap gas chromatography mass spectrometry method. It is concluded that cost-effective field analyses can be more effective when sample density is large.

This paper presents the algorithm "DETMAX" whose purpose is to construct experimental designs that are "D-optimal." These are designs for which the determinant of X'X is maximum, where X is the "matrix of independent variables" in the usual linear model y = X Beta + Epsilon. Although the algorithm does not guarantee D-optimality, it has performed well in many cases where D-optimal designs are known. Five examples are given, illustrating the use of DETMAX to construct designs "from scratch" and to augment existing data. A FORTRAN listing is available on request. [ABSTRACT FROM AUTHOR]

The effect of 2 retinoids, 13--retinoic acid and 4-methoxy-2,3,6-trimethylphenyl analog of retinoic acid ethyl amide (designated Roll-1430), on tracheal tumor development in hamsters exposed to N-nitro-so-N-methylurea was tested. Hamsters were in-tratracheally exposed either 18, 20, or 23 times to 1% N-nitroso-N-methylurea before the retinoids were administered in the diet. Evidence was presented which indicates that the great majority of the animals are free of invasive neoplasia at the start of retinoid feeding. In none of the 6 retinoid-treated groups could a statistically significant inhibition of tumor development be demonstrated. Hamsters treated with 13--retinoic acid (128 or 172 mg/kg of diet) tended to have an elevated cancer risk; this effect was at a statistically significant level in the group treated with 172 mg/kg of diet. The distribution of histologic tumor types seemed to be shifted in favor of adeno and mixed adeno-epidermoid tumors in the group receiving a low carcinogen dose and Roll-1430. Similar to earlier studies with retinyl acetate tested in hamsters and rats, 13- retinoic acid and the retinoic acid ethyl amide analog Roll-1430, failed to inhibit development of respiratory tract neoplasms. We suspect that the reason for this is the absence of significant promoting influences in the current lung cancer models and that retinoids act mostly as anti-promoters. [ABSTRACT FROM PUBLISHER]