Lipid microencapsulation allows slow release of organic acids and natural identical flavors along the swine intestine.

The purpose of the present work was to investigate the in vivo concentrations of sorbic acid and vanillin as markers of the fate of organic acids (OA) and natural identical flavors (NIF) from a microencapsulated mixture and from the same mixture non-microencapsulated, and the possible consequences on the intestinal microbial fermentation. Fifteen weaned pigs were selected from 3 dietary groups and were slaughtered at 29.5 +/- 0.27 kg of BW. Diets were (1) control; (2) control supplemented with a blend of OA and NIF microencapsulated with hydrogenated vegetable lipids (protected blend, PB); and (3) control supplemented with the same blend of OA and NIF mixed with the same protective matrix in powdered form but without the active ingredient coating (non-protected blend, NPB). Stomach, cranial jejunum, caudal jejunum, ileum, cecum, and colon were sampled to determine the concentrations of sorbic acid and vanillin contained in the blend and used as tracers. Sorbic acid and vanillin were not detectable in pigs fed the control, and their concentrations were not different in the stomach of PB and NPB treatments. Pigs fed PB showed a gradual decrease of the tracer concentrations along the intestinal tract, whereas pigs fed NPB showed a decline of tracer concentration in the cranial jejunum and onwards, compared with the stomach concentrations. Sorbic acid and vanillin concentrations along the intestinal tract were greater (P = 0.02) in pigs fed PB compared with pigs fed NPB. Pigs fed PB had lower (P = 0.03) coliforms in the caudal jejunum and the cecum than pigs fed the control or NPB. Pigs fed the control or PB had a greater (P = 0.03) lactic acid bacteria plate count in the cecum than pigs fed NPB, which showed a reduction (P = 0.02) of lactic acid concentrations and greater (P = 0.02) pH values in the caudal jejunum. The protective lipid matrix used for microencapsulation of the OA and NIF blend allowed slow-release of both active ingredients and prevented the immediate disappearance of such compounds upon exiting the stomach.

High-pressure liquid chromatographic-mass spectrometric determination of sorbic acid in urine: verification of formation of trans,trans-muconic acid.

An LC-MS method is described for the determination of urinary sorbic acid (SA), a common food additive, which allows to measure down to 4 microg/L of the compound. The method involves an acidic hydrolysis followed by solid-phase extraction. The method was applied to two volunteers who ingested SA and to 36 individuals with no dietary restriction. The results confirm that a little aliquot of ingested SA is found in urine also in humans. The significant correlation found between urinary levels of SA and trans,trans-muconic acid (MA) seems to indicate that the measurement of SA in urine could allow to estimate the amount of MA excreted following a dietary intake of SA and, consequently, to enhance the specificity of MA as a biomarker of benzene exposure. A point of clarification in future studies will be the actual chemical form of SA excreted, since our results clearly demonstrate that without hydrolysis only a very little amount of SA can be found even in subjects heavily exposed to SA.

Effect of sorbic acid administration on urinary trans,trans-muconic acid excretion in rats exposed to low levels of benzene.

Trans,trans-muconic acid (t,t-MA) is a biomarker of benzene exposure reflecting metabolic activation to trans,trans-muconaldehyde. t,t-MA background urinary levels are highly variable, thus limiting its use to exposure monitoring of levels over 1 ppm of benzene. Actually, sorbic acid (SA) is known to influence background excretion of t,t-MA in man, but only a few examples suggest that SA ingestion can enhance t,t-MA levels occurring together with benzene exposure. In this study, the effect of SA was investigated in benzene-exposed male Sprague-Dawley rats exposed to 1 ppm benzene for 6 h. Exposed animals had a 24-h urinary t,t-MA excretion higher than that observed in non-exposed animals (87+/-13 microg/kg vs 19+/-3 microg/kg body weight). The oral dose of 8 mg/kg body weight SA had no effect on urinary t,t-MA both in control and in benzene-exposed rats. Increases of t,t-MA levels in urine occurred at SA doses of 50-200 mg/kg body weight, and co-exposure to benzene and SA (50 and 100 mg/kg body weight) produced additive enhancement of t,t-MA excretion. These data demonstrate the dose-response relationship between SA administration and t,t-MA excretion. Our study showed that SA ingestion at doses equal to or greater than 50 mg/kg body weight significantly affects the t,t-MA urinary levels in rats exposed to 1 ppm of benzene for 6 h. These data support the conclusion that in man t,t-MA is not suitable for biomonitoring of low levels of benzene exposure.

Assessment of the correlation between exposure to benzene and urinary excretion of t, t-muconic acid in workers from a petrochemical plant.

OBJECTIVES: The investigation covered 148 workers from three plants with different levels of benzene exposure. The aim of the study was to assess the correlation between workers' personal exposure and urinary excretion of t, t-muconic acid (TTMA). METHODS: The personal exposure to benzene was measured by the sampling of the workplace air on sorbent tubes with active charcoal followed by elution with carbon disulphide and gas chromatographic determination. The individual internal exposure was assessed by determination of TTMA in urine by a liquid chromatographic method. The urine samples were collected at the beginning (t(0)) and end (t(1)) of the work shift. RESULTS: The individual whole-shift concentrations of benzene in workplace air in the three studied facilities varied from 0.1 to 67.53 mg/m(3). The concentration of TTMA at the beginning of the shift (t(0)) was from 0.02 to 2.53 mg/l and at the end of the shift (t(1)) was from 0.02 to 9.96 mg/l. Significant correlation was found between benzene level in workplace air and TTMA concentration in urine at the end of the work shift, with a correlation coefficient r=0.425 ( P=0.01). CONCLUSIONS: The analysis of the obtained results shows that TTMA can be used as a biological indicator for benzene exposure. The registered single cases of workers with unexpectedly high results for t, t-muconic acid are explained by their consumption of canned foods containing sorbic acid as a preservative. The subjects involved in similar studies should be advised not to consume canned foods 12 h before the examination.

Benzene exposure in car mechanics and road tanker drivers.

The purpose of this study was to identify professional factors related to benzene exposure and to deduce suitable safety measures. Atmospheric benzene, urinary muconic acid (tt-MA) and leukocyte alkaline phosphatase activity (LAPA) were evaluated among 66 car mechanics, 34 road tanker drivers, and 28 nonexposed workers. Professional and medical questionnaires were filled in at the same time. Atmospheric benzene was significantly higher among road tanker drivers than among car mechanics. The arithmetic mean +/- SD, median, and geometric mean values were, respectively, 0.48 +/- 1.49, 0.14, and 0.06 mg/m3 among car mechanics and 1.88 +/- 4.18, 0.68, and 0.65 mg/m3 among road tanker drivers. In the latter case the increase was caused by transport of unleaded petrol and correlated with the volume of the tank. Among car mechanics, tobacco smoking, windy conditions, dismantling of petrol filters, and handling of petrol increased atmospheric benzene levels. Urinary muconic acid was increased significantly among car mechanics (148 +/- 137, 127, and 111 micrograms/g) and among road tanker drivers (309 +/- 420, 137, and 151 micrograms/g) as compared with the controls (49 +/- 46, 33, and 33 micrograms/g). Among road tanker drivers, alcohol intake and transportation of unleaded petrol increased the excretion of muconic acid, which was also directly related to the volume of the tank. Among car mechanics, professional factors (dismantling of petrol filters, handling of and washing of hands with petrol) and nonprofessional factors (tobacco smoking and damaged skin on the hands and forearms) increased muconic acid excretion. In the control group, tobacco smoking increased its excretion. LAPA was not significantly modified among exposed workers. There was a weak but significant linear correlation between LAPA and muconic acid. These results suggest that to reduce exposure to benzene in unleaded petrol, individual and collective safety measures should be imposed in both occupations.

Concentrations of benzene in blood and S-phenylmercapturic and t,t-muconic acid in urine in car mechanics.

Different parameters of biological monitoring were applied to 26 benzene-exposed car mechanics. Twenty car mechanics worked in a work environment with probably high benzene exposures (exposed workers); six car mechanics primarily involved in work organization were classified as non-exposed. The maximum air benzene concentration at the work places of exposed mechanics was 13 mg/m3 (mean 2.6 mg/m3). Elevated benzene exposure was associated with job tasks involving work on fuel injections, petrol tanks, cylinder blocks, gasoline pipes, fuel filters, fuel pumps and valves. The mean blood benzene level in the exposed workers was 3.3 micrograms/l (range 0.7-13.6 micrograms/l). Phenol proved to be an inadequate monitoring parameter within the exposure ranges investigated. The muconic and S-phenylmercapturic acid concentrations in urine showed a marked increase during the work shift. Both also showed significant correlations with benzene concentrations in air or in blood. The best correlations between the benzene air level and the mercapturic and muconic acid concentrations in urine were found at the end of the work shift (phenylmercapturic acid concentration: r = 0.81, P < 0.0001; muconic acid concentration: r = 0.54, P < 0.05). In conclusion, the concentrations of benzene in blood and mercapturic and muconic acid in urine proved to be good parameters for monitoring benzene exposure at the workplace even at benzene air levels below the current exposure limits. Today working as a car mechanic seems to be one of the occupations typically associated with benzene exposure.

trans,trans-Muconic acid, a reliable biological indicator for the detection of individual benzene exposure down to the ppm level.

trans,trans-Muconic acid (2,4-hexadienedioic acid) (t,t-MA) is a minor benzene metabolite which can be used as a biological indicator for benzene exposure. The purpose of the study was to evaluate the limits of use of t,t-MA for detection and quantification of occupational exposures to benzene, particularly on an individual scale, phenol being used as the metabolite of reference. A simple and sensitive method previously described by the authors was carried out to analyse t,t-MA in 105 end-of-shift urinary samples from 23 workers exposed to benzene used as an extraction solvent for "concretes" recovery in the perfume industry. Good correlations were found between atmospheric benzene and both metabolites (uncorrected or corrected for creatinine) or between the metabolites themselves, with correlation coefficients from 0.81 to 0.91 (P < 0.0001). Correlation- coefficients were not improved after correction for creatinine. The overall individual benzene exposure range, median, and arithmetic mean were respectively 0.1-75, 4.5, and 9.0 ppm with corresponding t,t-MA excretion of 0.1-47.9, 5.2 and 8.9 mg/l (uncorrected) and phenol excretion of 1.4-298, 30.9, and 42.2 mg/l (uncorrected). In the control group (145 determinations for t,t-MA and 76 for phenol from 79 individuals) the range, median, and arithmetic mean were respectively < 0.04-0.66, 0.08, and 0.13 mg/l (uncorrected t,t-MA) and 1.5-42.0, 9.85 and 11.3 mg/l (uncorrected phenol). t,t-MA was far more specific than phenol and could be easily and practically used to estimate with a given probability the upper or lower corresponding benzene concentrations down to around the ppm level.(ABSTRACT TRUNCATED AT 250 WORDS)

Toxicology of sorbic acid and sorbates.

Sorbic acid and its salts have been subjected to an extensive battery of tests, including acute, short-term and chronic toxicity/carcinogenicity tests, two-generation reproduction and teratogenicity studies. These studies show that sorbic acid and sorbates have a very low level of mammalian toxicity, even in chronic studies at up to 10% of the diet, and are devoid of carcinogenic activity. They are non-mutagenic and non-clastogenic in vitro and in vivo. The low toxicity is explicable by the fact that sorbic acid is metabolized rapidly by similar pathways to other fatty acids. In humans, a few cases of idiosyncratic intolerances have been reported (non-immunological contact urticaria and pseudo-allergy). The frequency appears low but there are too few reported data for an accurate assessment of the true incidence. In extreme conditions (high concentrations and temperature) sorbic acid may react with nitrite to form mutagenic products but these mutagens are not detectable under normal conditions of use, even in curing brines.

Mutagenicity on chlorination of products formed by ozonation of naphthoresorcinol in water.

The mutagenicity of products formed by chlorination after ozonation of naphthoresorcinol in aqueous solution was assayed with Salmonella typhimurium strains TA98 and TA100 in the presence and absence of S9 mix from phenobarbital- and 5,6-benzoflavone-induced rat liver. Ozonated and subsequently chlorinated naphthoresorcinol was directly mutagenic, as was ozonated naphthoresorcinol, in both strains tested. The mutagenic activity at chlorination with 8 equivalents of chlorine per mole of naphthoresorcinol after ozonation was markedly higher than that at only ozonation. Of the identified ozonation products of naphthoresorcinol, muconic acid, after chlorination with 2 or 4 equivalents of chlorine per mole of the compound, induced direct mutagenicity against TA98 and TA100. The chlorination of glyoxal with 0.5 and 1 chlorine equivalents per mole of the compound was shown to produce direct mutagenicity toward TA98. The identification of the chlorination products of these compounds is also discussed.