Biomedical subjects
Publications and source records attributed to D H Fine.
The Thermal Energy Analyzer (TEA) has been modified to make it capable of detecting compounds such as N-nitrosamides. This modified TEA(amide) can be used with both gas chromatography (GC) and high-performance liquid chromatography (HPLC). Analysis of underivatized N-nitroso amides by GC-TEA(amide) and HPLC-TEA(amide) are also described.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The GLC/TEA method for N-nitrosodimethylamine (NDMA) in beer was studied collaboratively by 13 laboratories from 7 countries. Collaborators were asked to analyze a total of 10 randomly labeled samples of beer consisting of the following duplicates: a naturally contaminated commercial beer; a beer extremely low (ca 0.1 ppb) in NDMA; and the low NDMA beer spiked with 0.5, 1.9, and 5.0 ppb NDMA. The pooled repeatability and reproducibility coefficients of variation (CV) for all samples were 17% and 27%, respectively. However, when data from 2 laboratories (outliers) were omitted, the corresponding CV values improved considerably (11% and 15%, respectively). Variance analysis showed the presence of a significant laboratory-sample interaction when all data were used for analysis, but this interaction disappeared when data from the 2 outlying laboratories were excluded. The pooled percent recovery of the overall method (omitting outliers) was 101.4 +/- 3.5. All the laboratories detected NDMA in the low NDMA beer. The method was adopted official first action.
Reaction of N-methylaniline in solution with ca. 100,000 ppm gaseous NO2 leads to significant amounts of ring- and N-nitro products, in addition to N-methyl-N-nitrosoaniline. Reaction of heterocyclic amines in solution with 5-1000 ppm gaseous NO2 gives significant amounts of N-nitrosamines and much higher amounts of N-nitramines than those obtained from concentrated gaseous NO2. The results are interpreted as evidence that N-nitrosation proceeds via an unsymmetrical ON-ONO2 dimer, whereas N-nitration may involve a free-radical process involving NO2, itself.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A kinetic model for estimating the gastric synthesis of N-nitroso compounds and a method for estimating the risk from exposure to volatile nitrosamines are described. A tentative calculation of the possible risks for human gastric cancer, based on extrapolating from literature data on the induction of tumours in rats, suggests that the endogenous formation of non-volatile N-nitroso compounds is more important than that of volatile nitrosamines.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The largest human exposure to N-nitrosamines is in the industrial section. Leather tanners are exposed to N-nitrosodimethylamine at levels up to 47 microgram/m3, corresponding to 440 microgram/person/day. Workers in the curing area of tire factories are exposed to N-nitrosomorpholine at levels up to 27 microgram/m3, corresponding to a intake of 250 microgram/person/day. These industrial exposures are considerably greater than exposure via foodstuffs, beer, cosmetics, cutting fluids and herbicides.
Groups of 3-5 Swiss CD1 mice were gavaged with aqueous solutions of sodium nitrite (250 micrograms), followed immediately by morpholine (5 micrograms) or dimethylamine (250 micrograms). At subsequent intervals, up to 30-60 min, mice were frozen, pulverized in liquid nitrogen and extracted with methylene chloride. Volatile nitrosamines were then quantitatively determined using a Thermal Energy Analyzer, interfaced to GC or HPLC. Biosynthesis of both N-nitrosodimethylamine (NDMA) and N-nitrosomorpholine (NMOR) showed a time-dependent increase for 3 and 9 min, respectively, followed by a steady decline. Levels of NDMA and NMOR were generally less than 0.1 ng/g in control mice gavaged with amine or nitrite alone. Zero-time recovery of NDMA and NMOR ranged from 50-70% and 70-90%, respectively. Biosynthesis of NDMA and NMOR was inhibited by prior administration of ascorbic acid, sodium ascorbate or ammonium sulfamate.
Explore the source record for details and available documents.
Under the NIOSH-sponsored contract, a total of 40 surveys were conducted at 28 manufacturing plants. The industries investigated were the fish, dye, leather, rubber and manufacturers and users of cutting fluids. NDELA, NMOR, NDMA and NDPhA were found in the air of several factories. In a chrome tannery, NDMA was identified at levels as high as 47 micrograms/m3 and NMOR was found at 27 micrograms/m3 in a rubber tire plant. This study has resulted in an increased understanding of man's exposure to exogenous N-nitrosamines. It is conceivable, from the information obtained in this study, that nitrosamine exposure comparable to that in the tire and rubber industry exists in other industries not yet surveyed. NIOSH is continuing its research on nitrosamines in the industrial environment. A full, industry-wide report on the 40 plant surveys is being compiled for publication.