'Real-world' compensatory behaviour with low nicotine concentration e-liquid: subjective effects and nicotine, acrolein and formaldehyde exposure.

AIMS: To compare the effects of (i) high versus low nicotine concentration e-liquid, (ii) fixed versus adjustable power and (iii) the interaction between the two on: (a) vaping behaviour, (b) subjective effects, (c) nicotine intake and (d) exposure to acrolein and formaldehyde in e-cigarette users vaping in their everyday setting. DESIGN: Counterbalanced, repeated measures with four conditions: (i) low nicotine (6 mg/ml)/fixed power; (ii) low nicotine/adjustable power; (iii) high nicotine (18 mg/ml)/fixed power; and (iv) high nicotine/adjustable power. SETTING: London and the South East, England. PARTICIPANTS: Twenty experienced e-cigarette users (recruited between September 2016 and February 2017) vaped ad libitum using an eVic Supreme™ with a 'Nautilus Aspire' tank over 4 weeks (1 week per condition). MEASUREMENTS: Puffing patterns [daily puff number (PN), puff duration (PD), interpuff interval (IPI)], ml of e-liquid consumed, changes to power (where permitted) and subjective effects (urge to vape, nicotine withdrawal symptoms) were measured in each condition. Nicotine intake was measured via salivary cotinine. 3-Hydroxypropylmercapturic acid (3-HPMA), a metabolite of the toxicant acrolein, and formate, a metabolite of the carcinogen formaldehyde, were measured in urine. FINDINGS: There was a significant nicotine concentration × power interaction for PD (P < 0.01). PD was longer with low nicotine/fixed power compared with (i) high nicotine/fixed power (P < 0.001) and (ii) low nicotine/adjustable power (P < 0.01). PN and liquid consumed were higher in the low versus high nicotine condition (main effect of nicotine, P < 0.05). Urge to vape and withdrawal symptoms were lower, and nicotine intake was higher, in the high nicotine condition (main effects of nicotine: P < 0.01). While acrolein levels did not differ, there was a significant nicotine × power interaction for formaldehyde (P < 0.05). CONCLUSIONS: Use of a lower nicotine concentration e-liquid may be associated with compensatory behaviour (e.g. higher number and duration of puffs) and increases in negative affect, urge to vape and formaldehyde exposure.

Trichloroethylene-induced formic aciduria in the male C57 Bl/6 mouse.

1, 1, 2-Trichloroethylene (TCE) is of environmental concern, due to evaporation while handling, chemical processing and leakage from chemical waste sites, leading to its contamination of ground water and air. For several decades there has been issues about possible long term health effects of TCE but recently the International Agency for Research on Cancer (IARC) and the US Environmental Protection Agency classified TCE as a human carcinogen. Links having been established between occupational exposures and kidney cancer and possible links to non-Hodgkin lymphoma and liver cancer, but there is more still more to learn. In male rats, TCE produces a small increase in the incidence of renal tubule tumours but not in female rats or mice of either sex. However, chronic renal injury was seen in these bioassays in both sexes of rats and mice. The mechanism of kidney injury from TCE is thought to be due to reductive metabolism forming a cysteine conjugate that is converted to a reactive metabolite via the enzyme cysteine conjugate ß-lyase. However, TCE also produces a marked and sustained formic aciduria in male rats and it has been suggested that long term exposure to formic acid could lead to renal tubule injury and regeneration. In this study we have determined if TCE produces formic aciduria in male mice following a single and repeat dosing. Male C57 Bl/6OlaHsd mice were dosed with 1000mg/kg by ip injection and urine collected overnight 24, 48, 72 and 96h after dosing. Formic acid was present in urine 24h after dosing, peaked around 48h at 8mg formic acid excreted/mouse, and remained constant over the next 24h and was not back to normal 96h after dosing. This was associated with a marked acidification of the urine. Plasma creatinine and renal pathology was normal. Plasma kinetics of formic acid showed it was readily cleared with an initial half-life of 2.42h followed by a slower rate with a half-life of 239h. Male mice were then dosed twice/week at 1000mg/kg TCE for 56days, as anticipated there was a marked and sustained formic aciduria over the duration of the study. This was associated with acidification of the urine, mild diuresis and a marked fall in urinary ammonia. Six biomarkers of renal injury KIM-1, NGAL, NAG, Cystatin-c, Albumin and IL-18 were measured in urine over time and they all showed a small increase at the later time points indicative of early markers of renal injury. However, there was no histological evidence of renal damage or renal tubule cell proliferation after 8 weeks' exposure to TCE. The concentration of formic acid in plasma at the end of the study was 1.05±0.61mM compared to control, 0.39±0.17mM. In the liver, formic acid was present at a concentration of 1mM in both control and treated mice while in the kidney it was higher at 2mM in both treated and controls. We also report that trichloroacetic acid (TCA) a metabolite of TCE also causes formic aciduria, at doses likely to arise in vivo after 1000mg/kg TCE namely 16 and 32mg/kg. Urinary formic acid peaked 24h after dosing at 4mg formic acid excreted/mouse. Thus, as in male and female rats (Yaqoob et al., 2013) male mice show a marked formic aciduria following TCE which after 8 weeks' exposure did not produce renal injury, but the small rise in renal biomarkers suggest renal damage may occur following longer exposure. Thus, TCE-induced formic aciduria may be a contributor factor in the chronic renal injury seen in male and female rats and mice.

Environmental and biological monitoring of occupational formaldehyde exposure resulting from the use of products for hair straightening.

The evaluation of formaldehyde (FD) exposure in beauty salons, due to the use of hair straightening products, and its relation with genotoxicity biomarkers was performed in this study. Regardless of official recommendations, the inappropriate use of homemade hair creams has became a popular practice in Brazil, and high formaldehyde content in the "progressive straightening" creams can contain mutagens that could increase the incidence of neoplasia in those people who use them. Damage to DNA was assessed by conducting a micronuclei test (MNT) on buccal cells and the comet assay on heparinized venous blood samples. A total of 50 volunteers were recruited at six different beauty salons (labeled A to F). At two salons that used products that did not contain FD (salons D and E), environmental FD concentrations were 0.04 and 0.02 ppm. In contrast, the products used at salons A, B, C, and F contained 5.7, 2.61, 5.9, and 5.79% of FD, and these salons had environmental FD concentrations of 0.07, 0.14, 0.16, and 0.14 ppm, respectively. Comparison of the beauty salon workers from each of the six beauty salons revealed significant differences in urinary formic acid (FA) concentration before exposure (p = 0.016), urinary FA after exposure (p = 0.004), variation in FA concentration before and after exposure (p = 0.018), environmental FD concentration (p < 0.001), cytogenetic damage detected by the comet assay according to both damage index (p < 0.001) and frequency of damage (p < 0.001), and for karyorrhexis only according to the MNT (p = 0.001).

Assessment of lipid peroxidation and p53 as a biomarker of carcinogenesis among workers exposed to formaldehyde in the cosmetic industry.

Despite the wide use of cosmetic products, they exert a number of health effects on tissues ranging from irritation to cancer. Our study aimed at assessing the effect of formaldehyde on lipid peroxidation and verifying the susceptibility to carcinogenesis using p53 as a biomarker among workers exposed to formaldehyde in cosmetic industry. Our entire exposed group (n = 40) and the controls (n = 20) were subjected to estimation of formate in urine, serum malondialdehyde (MDA), and p53. Also, complete blood picture, liver, and kidney function tests were carried out. The study revealed significant increase in the levels of formate, MDA, and p53 in the exposed group compared with their control group. Our results showed that workers in cosmetic industry had significant exposure to formaldehyde. Furthermore, the study pointed to the negative impact of formaldehyde as a cause of oxidative stress and suspicious carcinogen.

Evaluation of genotoxicity in workers exposed to low levels of formaldehyde in a furniture manufacturing facility.

Formaldehyde (FA) is a chemical widely used in the furniture industry and has been classified as a potential human carcinogen. The purpose of this study was to evaluate the occupational exposure of workers to FA at a furniture manufacturing facility and the relationship between environmental concentrations of FA, formic acid concentration in urine, and DNA damage. The sample consisted of 46 workers exposed to FA and a control group of 45 individuals with no history of occupational exposure. Environmental concentrations of FA were determined by high-performance liquid chromatography. Urinary formic acid concentrations were determined by gas chromatography with flame ionization detector. DNA damage was evaluated by the micronucleus (MN) test performed in exfoliated buccal cells and comet assay with venous blood. The 8-h time-weighted average of FA environmental concentration ranged from 0.03 ppm to 0.09 ppm at the plant, and the control group was exposed to a mean concentration of 0.012 ppm. Workers exposed to higher environmental FA concentrations had urinary formic acid concentrations significantly different from those of controls (31.85 mg L(-1) vs. 19.35 mg L(-), p ≤ 0.01 Mann-Whitney test). Significant differences were found between control and exposed groups for the following parameters: damage frequency and damage index in the comet assay, frequency of binucleated cells in the MN test, and formic acid concentration in urine. The frequency of micronuclei, nuclear buds, and karyorrhexis did not differ between groups. There was a positive correlation between environmental concentrations of FA and damage frequency (Spearman's rank correlation coefficient [r s] = 0.24), damage index (r s = 0.21), binucleated cells (r s = 0.34), and urinary formic acid concentration (r s = 0.63). The results indicate that, although workers in the furniture manufacturing facility were exposed to low environmental levels of FA, this agent contributes to the observed increase in cytogenetic damage. In addition, urinary formic acid concentrations correlated strongly with occupational exposure to FA.

Effects of formaldehyde on lymphocyte subsets and cytokines in the peripheral blood of exposed workers.

Formaldehyde (FA) is a well-known irritant, and it is suggested to increase the risk of immune diseases and cancer. The present study aimed to evaluate the distribution of major lymphocyte subsets and cytokine expression profiles in the peripheral blood of FA-exposed workers. A total of 118 FA-exposed workers and 79 controls were enrolled in the study. High performance liquid chromatography, flow cytometry, and cytometric bead array were used to analyze FA in air sample and formic acid in urine, blood lymphocyte subpopulations, and serum cytokines, respectively. The FA-exposed workers were divided into low and high exposure groups according to their exposure levels. The results showed that both the low and high FA-exposed groups had a significant increase of formic acid in urine when compared to the controls. Both the low and high exposure groups had a significant increase in the percentage of B cells (CD19+) compared to the control group (p<0.01). A significant increase in the percentage of the natural killer (NK) cells (CD56+) was observed in the low exposure group compared to the control (p = 0.013). Moreover, the FA-exposed workers in both exposure groups showed a significant higher level of IL-10 but lower level of IL-8 than the control (p<0.01). Subjects in the high exposure group had a higher level of IL-4 but a lower level of IFN-γ than the control (p<0.05). Finally, there is a significant correlation between the levels of IL-10, IL-4, and IL-8 and formic acid (p<0.05). The findings from the present study may explain, at least in part, the association between FA exposure and immune diseases and cancer.

Trichloroethylene and trichloroethanol-induced formic aciduria and renal injury in male F-344 rats following 12 weeks exposure.

Trichloroethylene (TCE) is widely used as a cleaning and decreasing agent and has been shown to cause liver tumours in rodents and a small incidence of renal tubule tumours in male rats. The basis for the renal tubule injury is believed to be related to metabolism of TCE via glutathione conjugation to yield the cysteine conjugate that can be activated by the enzyme cysteine conjugate ß-lyase in the kidney. More recently TCE and its major metabolite trichloroethanol (TCE-OH) have been shown to cause formic aciduria which can cause renal injury after chronic exposure in rats. In this study we have compared the renal toxicity of TCE and TCE-OH in rats to try and ascertain whether the glutathione pathway or formic aciduria can account for the toxicity. Male rats were given TCE (500mg/kg/day) or TCE-OH at (100mg/kg/day) for 12 weeks and the extent of renal injury measured at several time points using biomarkers of nephrotoxicity and prior to termination assessing renal tubule cell proliferation. The extent of formic aciduria was also determined at several time points, while renal pathology and plasma urea and creatinine were determined at the end of the study. TCE produced a very mild increase in biomarkers of renal injury, total protein, and glucose over the first two weeks of exposure and increased Kim-1 and NAG in urine after 1 and 5 weeks exposure, while TCE-OH did not produce a consistent increase in these biomarkers in urine. However, both chemicals produced a marked and sustained increase in the excretion of formic acid in urine to a very similar extent. The activity of methionine synthase in the liver of TCE and TCE-OH treated rats was inhibited by about 50% indicative of a block in folate synthesis. Both renal pathology and renal tubule cell proliferation were reduced after TCE and TCE-OH treatment compared to controls. Our findings do not clearly identify the pathway which is responsible for the renal toxicity of TCE but do provide some support for metabolism via glutathione conjugation.

Formate can differentiate between hyperhomocysteinemia due to impaired remethylation and impaired transsulfuration.

Formate can differentiate between hyperhomocysteinemia due to impaired remethylation and impaired transsulfuration. Am J Physiol Endocrinol Metab 301: E000-E000, 2011. First published September 20, 2011; 10.1152/ajpendo.00345.2011.-We carried out a (1)H-NMR metabolomic analysis of sera from vitamin B(12)-deficient rats. In addition to the expected increases in methylmalonate and homocysteine (Hcy), we observed an approximately sevenfold increase in formate levels, from 64 µM in control rats to 402 µM in vitamin B(12)-deficient rats. Urinary formate was also elevated. This elevation of formate could be attributed to impaired one-carbon metabolism since formate is assimilated into the one-carbon pool by incorporation into 10-formyl-THF via the enzyme 10-formyl-THF synthase. Both plasma and urinary formate were also increased in folate-deficient rats. Hcy was elevated in both the vitamin B(12)- and folate-deficient rats. Although plasma Hcy was also elevated, plasma formate was unaffected in vitamin B(6)-deficient rats (impaired transsulfuration pathway). These results were in accord with a mathematical model of folate metabolism, which predicted that reduction in methionine synthase activity would cause increased formate levels, whereas reduced cystathionine ß-synthase activity would not. Our data indicate that formate provides a novel window into cellular folate metabolism, that elevated formate can be a useful indicator of deranged one-carbon metabolism and can be used to discriminate between the hyperhomocysteinemia caused by defects in the remethylation and transsulfuration pathways.

Headspace in-tube extraction gas chromatography-mass spectrometry for the analysis of hydroxylic methyl-derivatized and volatile organic compounds in blood and urine.

A novel headspace in-tube extraction gas chromatography-mass spectrometry (ITEX-GC-MS) approach was developed for broad-scale analysis of low molecular weight organic compounds in blood and/or urine. One sample was analyzed following in-vial derivatization with dimethyl sulfate for ethylene glycol (EG), glycolic acid (GA), formic acid (FA), other hydroxylic compounds, and another sample for underivatized volatile organic compounds. Tenax adsorbent resin was used in the microtrap, and a porous layer, open tubular GC capillary column was used for separation. MS was operated in the full-scan mode, identification was based on the Automated Mass Spectral Deconvolution and Identification System, and quantification was based on extracted ions. The limits of quantification for EG, GA, and FA in blood were 10, 50, and 30 mg/L, respectively, and the expanded uncertainties of measurement were 20%, 16%, and 14%, respectively. The procedure allowed for the first time the inclusion of EG and GA as their methyl derivatives within a quantitative HS analysis. The ITEX method described here was more sensitive for analysis of volatile organic compounds than the corresponding static headspace analysis as demonstrated for 11 representative compounds.

(1)H nuclear magnetic resonance metabolomics analysis identifies novel urinary biomarkers for lung function.

Chronic obstructive pulmonary disease (COPD), characterized by chronic airflow limitation, is a serious public health concern. In this study, we used proton nuclear magnetic resonance ((1)H NMR) spectroscopy to identify and quantify metabolites associated with lung function in COPD. Plasma and urine were collected from 197 adults with COPD and from 195 without COPD. Samples were assayed using a 600 MHz NMR spectrometer, and the resulting spectra were analyzed against quantitative spirometric measures of lung function. After correcting for false discoveries and adjusting for covariates (sex, age, smoking) several spectral regions in urine were found to be significantly associated with baseline lung function. These regions correspond to the metabolites trigonelline, hippurate and formate. Concentrations of each metabolite, standardized to urinary creatinine, were associated with baseline lung function (minimum p-value = 0.0002 for trigonelline). No significant associations were found with plasma metabolites. Urinary hippurate and formate are often related to gut microflora. This could suggest that the microbiome varies between individuals with different lung function. Alternatively, the associated metabolites may reflect lifestyle differences affecting overall health. Our results will require replication and validation, but demonstrate the utility of NMR metabolomics as a screening tool for identifying novel biomarkers of pulmonary outcomes.

[Formaldehyde metabolism in semicarbazide intoxication].

Subchronic administration of semicarbazide in the experiment with the rats was used to reduce the formaldehyde level in the organism in order to reveal the interaction between formaldehyde metabolism and biochemical parameters, which define the oxidant-antioxidant system condition and NO metabolism. It has been found that under semicarbazide impact the generation of free radicals, ROS, nitrite and nitrate were enhanced while aldehydes level was reduced that resulted from not only semicarbazide effect like the aldehydes acceptor, but the formaldehyde synthesis slowdown and acceleration of its transformation into format as well. We suppose that formaldehyde plays certain role in the development of connective tissue pathology.

Characterization of inflammatory bowel disease with urinary metabolic profiling.

OBJECTIVES: Distinguishing between the inflammatory bowel disease (IBD), Crohn's disease (CD), and ulcerative colitis (UC) is important for both management and prognostic reasons. Discrimination using noninvasive techniques could be an adjunct to conventional diagnostics. Differences have been shown between the intestinal microbiota of CD and UC patients and controls; the gut bacteria influence specific urinary metabolites that are quantifiable using proton high-resolution nuclear magnetic resonance (NMR) spectroscopy. This study tested the hypothesis that such metabolites differ between IBD and control cohorts, and that using multivariate pattern-recognition analysis, the cohorts could be distinguished by urine NMR spectroscopy. METHODS: NMR spectra were acquired from urine samples of 206 Caucasian subjects (86 CD patients, 60 UC patients, and 60 healthy controls). Longitudinal samples were collected from 75 individuals. NMR resonances specific for metabolites influenced by the gut microbes were studied, including hippurate, formate, and 4-cresol sulfate. Multivariate analysis of all urinary metabolites involved principal components analysis (PCA) and partial least squares discriminant analysis (PLS-DA). RESULTS: Hippurate levels were lowest in CD patients and differed significantly between the three cohorts (P<0.0001). Formate levels were higher and 4-cresol sulfate levels lower in CD patients than in UC patients or controls (P=0.0005 and P=0.0002, respectively). PCA revealed clustering of the groups; PLS-DA modeling was able to distinguish the cohorts. These results were independent of medication and diet and were reproducible in the longitudinal cohort. CONCLUSIONS: Specific urinary metabolites related to gut microbial metabolism differ between CD patients, UC patients, and controls. The emerging technique of urinary metabolic profiling with multivariate analysis was able to distinguish these cohorts.

Formate excretion in urine of rats fed dimethylaminoazobenzene-rich diets: the possibility of formate formation from D-lactate.

This experiment was carried out to evaluate the possibility of degradation of d-lactate into formate and acetaldehyde. In order to induce hyperproduction of d-lactate in rats. Donryu male albino rats were fed diets containing 0.064% 3'-methyl-4-dimethylaminoazobenzene (3'-MDAB), 4'-methyl-4-dimethylaminoazobenzene (4'-MDAB) or 2-methyl-4-dimethylaminoazobenzene (2-MDAB) for 10 weeks. During the experiment, body mass, food and water intake and volume of urine were documented. Methylglyoxal, D-lactate and formate in the urine samples were determined. On the first day of the eleventh week, methylglyoxal, D-lactate, glutathione and enzymatic activities of demethylation and glyoxalase I and II in liver were measured. Methylglyoxal, D-lactate and clinical chemistry parameters of blood plasma were also measured. The levels of methylglyoxal and D-lactate in livers of rats fed 3'-MDAB were very high, while those of 2-MDAB fed-rats and the control group were the same. The fact that glyoxalase I activity and the level of glutathione, a cofactor of glyoxalase I, were high in the livers of the 3'-MDAB-fed rats can explain the elevated levels of methylglyoxal and D-lactate in the liver. The most striking results were the elevated formate levels in the urine of rats fed 3'- and 4'-MDAB in a precancerous state. The degradation of D-lactate, an end product of the methylglyoxal bypass, into acetaldehyde and formate was suggested as a possible way to explain the results.

Determination of thiazolidine-4-carboxylates in urine by chloroformate derivatization and gas chromatography-electron impact mass spectrometry.

The derivatization method of thiazolidine-4-carboxylic acid (TZCA) and methyl-thiazolidine-4-carboxylic acid (Me-TZCA) in urine with alcohol/chloroformate was achieved. TZCA and Me-TZCA were derivatized in one step in urine with ethyl chloroformate in 1 min at room temperature. The derivatives of TZCA and Me-TZCA had very good chromatographic properties and offered very sensitive response for gas chromatography-electron impact ionization-mass spectrometry (GC-EI-MS). On the basis of derivatization, the method for simultaneous determination of TZCA and Me-TZCA in human urine was developed. Deuterated Me-TZCA (Me-TZCA-d(4)) was synthesized as the internal standard (IS) for the analysis of urine samples. TZCA and Me-TZCA were derivatized and extracted from urine at pH 9.5 with toluene, and then the dried extract was dissolved with 100 microl ethyl acetate and injected in GC/MS system. The recoveries of TZCA and Me-TZCA were about 102 and 103%, respectively, at the concentration of 0.05 mg/l. The method detection limits (MDL) were 1.0 and 0.5 microg/l, respectively, for TZCA and Me-TZCA in 1 ml human urine. The coefficients of variation of TZCA and Me-TZCA were less than 6% at the concentrations of 0.05 and 0.2 mg/l, respectively. To assess the formation of TZCA during inhalation with formaldehyde (FA) (about 3.1 and 38.1 ppm FA in air), urine samples from rats were taken during 3 days after initiation of treatment. The mean amount of TZCA determined was 0.07 mg/l in control group and 0.18 mg/l during treatment with 3.1 ppm. The TZCA levels increased up to about 1.01 mg/l during treatment with 38.1 ppm. It is planned to study whether urinary TZCA can be used as an indicator in the biological monitoring of exposure to FA.

Effect of oral creatine supplementation on urinary methylamine, formaldehyde, and formate.

PURPOSE: It has been claimed that oral creatine supplementation might have potential cytotoxic effects on healthy consumers by increasing the production of methylamine and formaldehyde. Despite this allegation, there has been no scientific evidence obtained in humans to sustain or disprove such a detrimental effect of this widely used ergogenic substance. METHODS: Twenty young healthy men ingested 21 g of creatine monohydrate daily for 14 consecutive days. Venous blood samples and 24-h urine were collected before and after the 14th day of supplementation. Creatine and creatinine were analyzed in plasma and urine, and methylamine, formaldehyde, and formate were determined in 24-h urine samples. RESULTS: Oral creatine supplementation increased plasma creatine content 7.2-fold (P < 0.001) and urine output 141-fold (P < 0.001) with no effect on creatinine levels. Twenty-four-hour urine excretion of methylamine and formaldehyde increased, respectively, 9.2-fold (P = 0.001) and 4.5-fold (P = 0.002) after creatine feeding, with no increase in urinary albumin output (9.78 +/- 1.93 mg x 24 h(-1) before, 6.97 +/- 1.15 mg x 24 h(-1) creatine feeding). CONCLUSION: This investigation shows that short-term, high-dose oral creatine supplementation enhances the excretion of potential cytotoxic compounds, but does not have any detrimental effects on kidney permeability. This provides indirect evidence of the absence of microangiopathy in renal glomeruli.

A combined (1)H NMR and HPLC-MS-based metabonomic study of urine from obese (fa/fa) Zucker and normal Wistar-derived rats.

(1)H NMR and HPLC-MS were used to generate metabolite fingerprints for the metabonomic analysis of urine obtained from both male and female Zucker obese (fa/fa) rats, used as a model of type II diabetes, and normal male Wistar-derived animals. The resulting data were subjected to chemometric analysis (principal components analysis and partial least squares discriminant analysis) to investigate the effects of strain, diurnal variation is strain, diurnal variation and gender and gender on metabolite profiles. In the case of strain, (1)H NMR spectroscopic analysis revealed increased taurine, hippurate and formate and decreased betaine, alpha-ketoglutarate, succinate and acetate in samples from Zucker-obese compared to Wistar-derived rats. HPLC-MS analysis detected increased hippurate and ions at m/z 255.0640 and 285.0770 in positive, and 245.0122 and 261.0065 in negative electrospray ionisation (ESI), respectively, for the Zucker obese samples. Both techniques enable the detection of diurnal variation in the urine of male and female Zucker rats, marked by increases in taurine, creatinine, allantoin and alpha-ketoglutarate by (1)H NMR, and ions at m/z 285.0753, 291.0536 and 297.1492 (positive ESI) and 461.1939 (negative ESI) using HPLC-MS, in the evening samples. Differences between male and female Zucker rats were also observed. Compared to samples from male rats hippurate, succinate, alpha-ketoglutarate and dimethylglycine ((1)H NMR) were elevated in the urine of female animals together with ions at, e.g., m/z 431.1047, 325.0655, 271.0635 and 447.0946 (positive ESI) and m/z 815.5495 and 459.0985 (negative ESI) by HPLC-MS. Both analytical techniques used in this study were able to detect differences between normal and Zucker obese rats, which may provide markers of metabolic disease.

Increased formic acid excretion and the development of kidney toxicity in rats following chronic dosing with trichloroethanol, a major metabolite of trichloroethylene.

The chronic toxicity of trichloroethanol, a major metabolite of trichloroethylene, has been assessed in male Fischer rats (60 per group) given trichloroethanol in drinking water at concentrations of 0, 0.5 and 1.0 g/l for 52 weeks. The rats excreted large amounts of formic acid in urine reaching a maximum after 12 weeks ( approximately 65 mg/24 h at 1 g/l) and thereafter declining to reach an apparent steady state at 40 weeks (15-20 mg/24 h). Urine from treated rats was more acidic throughout the study and urinary methylmalonic acid and plasma N-methyltetrahydrofolate concentrations were increased, indicating an acidosis, vitamin B12 deficiency and impaired folate metabolism, respectively. The rats treated with trichloroethanol developed kidney damage over the duration of the study which was characterised by increased urinary NAG activity, protein excretion (from 4 weeks), increased basophilia, protein accumulation and tubular damage (from 12 to 40 weeks), increased cell replication (at week 28) and evidence in some rats of focal proliferation of abnormal tubules at 52 weeks. It was concluded that trichloroethanol, the major metabolite of trichloroethylene, induced nephrotoxicity in rats as a result of formic acid excretion and acidosis.

Drug and chemical metabolites in clinical toxicology investigations: the importance of ethylene glycol, methanol and cannabinoid metabolite analyses.

Metabolic pathways in humans have been elucidated for most therapeutic drugs, drugs of abuse, and various chemical/solvents. In most drug overdose cases and chemical exposures, laboratory analysis is directed toward identification and quantitation of the unchanged drug or chemical in a biologic fluid such as serum or whole blood. Specifically, most clinical laboratories routinely screen and quantitate unchanged methanol and/or ethylene glycol in suspected poisonings without toxic metabolite analysis. Martin-Amat established in 1978 that methanol associated toxicity to the optic nerve in human poisonings was due to the toxic metabolite formic acid found in methanol poisonings and not due to the direct action by unchanged methanol. Jacobsen reported in 1981 that ethylene glycol central nervous system and renal toxicity were primarily due to one acidic metabolite (glycolic acid) and not due to unchanged ethylene glycol. The first objective of this review is to describe clinical experience with formic acid and glycolic acid analysis in methanol and ethylene glycol human poisonings. Drug metabolite analysis also provides useful information in the assessment and monitoring of drug use in psychiatry and substance abusing populations. Drug analysis in substance abuse monitoring is focused on urine analysis of one or more major metabolites, and less frequently on the unchanged drug(s). Serial monitoring of the major urinary cannabinoid metabolite (delta(9)-THC-COOH) to creatinine ratios in paired urine specimens (collected at least 24 h apart) could differentiate new marijuana or hashish use from residual cannabinoid metabolite excretion in urine after drug use according to Huestis. The second objective is to demonstrate that creatinine corrected urine specimens positive for cannabinoids may help differentiate new marijuana use from the excretion of residual delta(9) -THC-COOH in chronic users of marijuana or hashish. Analysis of toxic chemical metabolites are helpful in the assessment and treatment of chemical poisoning whereas serial monitoring of urinary cannabinoid metabolites are predictive of illicit drug use in the substance abusing population.

Isopropanol and methylformate exposure in a foundry: exposure data and neurobehavioural measurements.

OBJECTIVES: The aim of this study was to determine the dose-effect relationship between solvent exposure and acute neurobehavioural effects at the worksite. METHODS: In a balanced design, ten workers in a Swiss foundry were monitored for 15 days at ten different times during work. Urine samples were taken in the morning and at the time of examination, and personal exposure to isopropanol and methylformate was measured with active samplers. Neurobehavioural tests such as postural balance (bipedal, bipedal blind, monopedal), simple reaction time and digit span of the Neurobehavioural Evaluation System (NES2) and a combined memory and reaction-time test, the combi-test, were performed. A rating of well-being, and the last consumption of alcohol, caffeine, nicotine and medication were reported. RESULTS: Average environmental concentrations of isopropanol were at 44 ppm ( +/- 16 ppm), and at 36 ppm (+/-21 ppm) for methylformate. Maximum values of personal exposure to isopropanol reached barely the maximal allowable concentration (MAC) value (400 ppm); the methylformate personal exposure of three workers exceeded the MAC value (100 ppm). Urine concentrations of methanol were high (3.1 +/- 2.3 mg/l in the morning, 7.8 +/- 4.9 mg/l after exposure) compared with the results of other studies; concentrations of isopropanol were rather low (0.88 +/- 0.73 mg/l after exposure). CONCLUSIONS: Nevertheless, between personal exposure and biomonitoring, linear correlation was found. Methylformate exposure correlated with methanol and formic acid concentration in the urine, and isopropanol exposure with its concentration in the urine. With the neurobehavioural tests used, no solvent effect in relation to the dose could be determined.

Urinary methanol and formic acid as indicators of occupational exposure to methyl formate.

OBJECTIVE: To evaluate the validity of methanol (MeOH) and formic acid (FA) in urine as biological indicators of methyl formate (MF) exposure in experimental and field situations. METHODS: The subjects were 28 foundrymen and two groups of volunteers (20 control and 20 exposed). Exposure assessment of the workers was performed by personal air and biological monitoring. Methyl formate vapour collected on charcoal tube was analysed by gas chromatography. The concentration of MF in the exposure chamber (volunteer-study) was monitored by two independent methods [flame ionisation detection (FID) and Fourier transformation infra-red detection (FTIR)]. Urinary metabolites (MeOH and FA) were analysed separately by headspace gas chromatography. RESULTS: The volunteers exposed to 100 ppm MF vapour at rest for 8 h excreted 3.62 +/- 1.13 mg MeOH/l (mean +/- SD) at the end of the exposure. This was statistically different (P < 0.001) from pre-exposure MeOH excretion (2.15 +/- 0.80 mg/1), or from that of controls (1.69 +/- 0.48 mg/l). The urinary FA excretion was 32.2 +/- 11.3 mg/g creatinine after the exposure, which was statistically different (P < 0.001) from pre-exposure excretion (18.0 +/- 9.3 mg/g creatinine) or that of controls (13.8 +/- 7.9 mg/g creatinine). In foundrymen, the urinary FA excretion after the 8 h workshift exposure to a time weighted average (TWA) concentration of 2 to 156 ppm MF showed a dose-dependent increase best modelled by a polynomial function. The highest urinary FA concentration was 129 mg/g creatinine. The pre-shift urinary FA of the foundrymen (18.3 +/- 5.6 mg/g creatinine) did not differ from that of controls (13.8 +/- 7.9 mg/g creatinine). The urinary MeOH excretion of the foundrymen after the shift, varied from < 1 to 15.4 mg/l, while the correlation with the preceding MF exposure was poor. The foundrymen excreted more (P = 0.01) FA (2.12 +/- 3.56 mg/g creatinine) after the workshift than experimentally, once-exposed volunteers (0.32 +/- 0.11 mg/g creatinine) at a similar inhaled MF level of 1 ppm). CONCLUSIONS: In spite of its high background level in non-exposed subjects, urinary FA seems to be a useful biomarker of methyl formate exposure. The question remains as to what is the reason for the differences in chronic and acute exposure respectively.