Distribution and predictors of urinary polycyclic aromatic hydrocarbon metabolites in two pregnancy cohort studies

Pregnant women and their fetuses represent susceptible populations to environmental contaminants. Exposure to polycyclic aromatic hydrocarbons (PAHs) among pregnant women may contribute to adverse birth outcomes such as preterm birth. Multiple previous studies have assessed airborne sources of PAHs among pregnant women but few have measured urinary PAH metabolites which can capture total exposure through multiple routes. The aim of this study was to bridge this knowledge gap by assessing longitudinal urinary PAH metabolite concentrations over two time points in pregnancy cohorts in Boston (N = 200) and Puerto Rico (N = 50) to better understand exposure distributions throughout pregnancy and how they relate to demographic factors. Urine samples were analyzed for 1-NAP, 2-NAP, 2-FLU, 1-PHE, 2,3-PHE, 4-PHE, 9-PHE, and 1-PYR. Concentrations of 2-NAP, 1-PYR, and 4-PHE were higher in Puerto Rico, while all other metabolites were present in higher concentrations in Boston. In Puerto Rico, intraclass correlation coefficients (ICC) were weak to moderate, ranging from 0.06 to 0.42. PAH metabolite concentrations were significantly higher among younger, heavier (except 1-NAP and 9-PHE), and less educated individuals in Boston only. Consistent significant associations between PAH concentrations and measured covariates were not found in Puerto Rico. Our results suggest that potentially important differences in PAH exposure exist between these two populations. Additionally, our results indicate that multiple urinary measurements are required to accurately assess PAH exposure throughout pregnancy.

Studies on the metabolism of Orange Rn in the pig

Orange RN (monosodium salt of 1-phenylazo-2-naphthol-6-sulphonic acid) was administered to female pigs either by intraveneous injection or by stomach tube. After intravenous injection of Orange RN, 7.8 mg/kg, the following metabolites were indentified in 24-hour urines: Orange RN (31%), 1-(4-hydroxyphenlazo)-2-naphthol-6-sulphonic acid (3%), p-aminophenol and 0-aminophenol (34% and 4% of the theoretical yield, respectively). 1-Amino-2-naphthol-6-sulphonic acid was present, but not determined. When the urine collection was extended to 72 hours the excretion of p-aminophenol accounted for the remainder of the phenylazo moiety. The excretion pattern for p-aminophenol suggest that Orange RN is partly excreted in the bile and thereafter undergoes azo reduction in the gut. After administration of Orange RN, 78 mg/kg, by stomach tube the following metabolites were identified in the urine: Total coloured metabolites (Orange RN and 1-(4-hydroxyphenylazo)-2-naphtholphenol-6-sulphinic acid) (0.4% of the theoretical yield), p-aminophenol and o-aminophenol (52% and 6% of the theoretical yield, respectively) and aniline (0.3% of the theoretical yield). 1-Amino-2-naphthol-6-sulphonic acid was present, but not determined.

Similar profile of urinary and faecal metabolites of 14C-carmoisine in male and pregnant female rats after oral administration

Pregnant rats received 14C-Carmoisine (200 mg kg-1; 25 microCi) by gavage on days 16-19 of gestation. The animals were killed and maternal tissues, amniotic fluid, placentae, foetal membranes and foetuses were analyzed for radioactivity. No evidence for the transplacental transfer of 14C-Carmoisine or its metabolites was obtained. Male rats were given a single oral administration of 14C-Carmoisine (200 mg kg-1; 25 microCi) and killed at different times after dosing. In both male and female animals, more than 90% of the radioactivity was excreted in faeces and urine within 64 h, and the results suggested that there was no significant absorption of the azodye and no preferential concentration of the red food colour or its metabolites in any particular tissue. Analyses by HPLC, combined with a radioactivity monitor (RAM), of urine and faeces of such animals show that five radioactive peaks were present in the radiochromatogram in addition to unmodified Carmoisine. The mean peak shows the retention time and the u.v. spectrum of authentic naphthionic acid. The results demonstrate that the pregnancy does not affect the kinetic and the metabolic profile of a single oral administration of the azodye Carmoisine given at different days of gestation.

Mutagenicity studies of urine and faecal samples from rats treated orally with the food colourings Brown FK and Red 2G

Urine and faecal extracts from rats given Brown FK or Red 2G orally (800 mg/kg body weight) were investigated for mutagenicity. Extracts were subjected to liquid fluctuation and plate incorporation assays with Salmonella typhimurium strains TA98 and TA100 in the presence and absence of liver microsomes and/or a beta-glucuronidase-sulphatase preparation. Urine from Red 2G-treated rats only exhibited direct activity when coloured fractions from polyamide-column concentrates were tested with TA100. All other urines, as well as aqueous and ether faecal extracts from animals receiving either colouring, were no more mutagenic than the respective control extracts obtained from the same animals prior to dosing.

Chromatographic assays for traces of potentially carcinogenic metabolites of two azo dyes, Direct Red 2 and Direct Blue 15, in rat, hamster and human urine

Specific, precise and sensitive methods are described for determining traces of potentially carcinogenic metabolites of Direct Red 2 and Direct Blue 15 in rat and hamster urine and to monitor the urine from workers who may be occupationally exposed to these dyes. This methodology is generally applicable to metabolites of azo dyes based on benzidine or three of its congeners. The benzidine-congener free amines, their mono and diacetylated analogs and alkaline hydrolyzable conjugates were determined after appropriate extraction and hydrolysis by HPLC or EC/GC. Residues of metabolites in rat, hamster, and human urine were determined at levels as low as 1 ppb. Supplementary information is also presented concerning hydrolysis of diacetylated metabolites and the stability of Direct Red 2 and Direct Blue 15 in rat, hamster and human urine.

N-acetyl-(1-amino-2-naphthol-6-sulphonic acid), a common metabolite of sunset yellow FCF, orange GGN and 1-amino-2-naphthol-6-sulphonic acid in rat urine

Sunset Yellow FCF, Orange GGN and 1-amino-2-naphthol-6-sulphonic acid (ANSA) were administered to male Wistar rats by stomach intubation. Aromatic sulphonic acids excreted in 24-h urines after enzymatic cleavage of the azo link in the dyes were isolated using a thoroughly elaborated ion-pair extraction method and further separated by means of a reversed-phase ion-pair liquid chromatographic system. Blank 24-h rat urines were extracted and run at the same time under identical analytical circumstances. In addition to the peaks corresponding to sulphanilic and metanilic acid and their N-acetylated derivatives, which are metabolites arising from Sunset Yellow FCF and Orange GGN, respectively, an important common peak appeared on the chromatograms, which was absent from the blank urine extracts. After analysis of 24-h urine of rats that had received ANSA, a peak with the same retention time as this unknown common peak could be detected under the same liquid chromatographic conditions, the retention time of which was different from that of the ANSA standard. However, after derivatization of the ANSA standard with acetic anhydride, followed by liquid chromatographic examination of the derivatised mixture, two peaks appeared on the chromatogram, the first of which had the same retention time and the same UV-spectrum as the unknown common peak in rat urine extracts. By means of semi-preparative liquid chromatographic separation and isolation, followed by further purification over a cation-exchange resin, the compound corresponding to the unknown common peak could be identified by FT-PMR spectroscopy as N-acetyl-ANSA.

Trace analysis of potentially carcinogenic metabolites of an azo dye and pigment in hamster and human urine as determined by two chromatographic procedures

Analytical chemical procedures are described for determining traces of possible metabolites of two azo compounds. Direct Black 38 and Pigment Yellow 12, in hamster urine and to monitor the urine from workers who may be occupationally exposed during the manufacture or use of the dye and pigment. These methods were required for metabolism studies designed to assess the hazards that may occur if the two compounds are converted by in vivo mechanisms to potential carcinogens. Salient elements of the procedure are: extraction of the free aromatic amines and neutral compounds; alkaline hydrolysis of the aqueous phase and extraction of any hydrolyzed conjugates as free amines, and the analysis of the free amines and acetylated metabolites directly by high pressure liquid chromatography or by electron capture gas chromatography after conversion of the amines to heptafluorobutyryl derivatives. Residues of metabolites in hamster and human urine were determined at levels as low as 1 ppb. Ancillary data concerning hydrolysis of diacetylated metabolites and partition values for possible metabolites in various solvent systems are also presented.

Microdetermination of naphthionic acid in serum and amniotic fluid

A simple, rapid, sensitive, and reproducible microdetermination of naphthionic acid (NA) in serum and amniotic fluid is described. The detection limit of the method is 1 ng NA in 20 microL serum, and 3 ng NA in 50 microL amniotic fluid. The concentration of nonderivatized NA was measured by fluorescence spectrophotometry (excitation 328 nm, emission 420 nm) of the supernate, after precipitation of proteins with absolute ethanol and heating for 30 min at 75 degrees C. Standard deviations of determinations for 2, 10, and 50 ng NA in 20 microL serum were 10.1, 7.59, and 7.64%, respectively. An analyst can perform about 100 determinations daily; results are available within 2 hr of sampling. A modification of the procedure to permit quantitation of NA in urine is also described.

Intestinal absorption of polymeric derivatives of the food dyes sunset yellow and tartrazine in rats

1. Absorption and metabolism of 14C-labelled sunset yellow (FD & C Yellow No. 6), tartrazine (FD & C Yellow No. 5) and high molecular weight polymeric derivatives of the two azo dyes were compared in rats. 2. A trace to 1.5 percent of unchanged monomeric dyes was excreted in urine and bile during the first 24 h after dosing. No unchanged dye was absorbed after administration of the polymeric derivatives. 3. In animals dosed with sunset yellow and its polymer derivative, absorption of the azo-bound cleavage product 1-amino-2-naphthol-6-sulphonic acid was 8.5 and 6.9 percent, respectively, while absorption of the cleavage product sulphanilic acid was 37.4 and 0 percent, respectively. 4. In animals dosed with tartrazine and its polymer derivative, absorption of the cleavage product aminopyrazolone and its metabolites was 4.0 and 4.6 percent, respectively. 5. Azo bond cleavage did not appear to be decreased in the polymer derivatives. However, the sulphanilic acid moiety of both dyes remained attached to the polymer backbone, resulting in a 95 percent decrease in sulphanilic acid absorption with polymeric tartrazine. 6. Decreased absorption of unchanged dyes and certain metabolites with the stable, non-absorbed polymeric derivatives may be significant in developing non-sensitizing substitutes for these two commonly used food colourants.