Emissions of Formamide and Ammonia from Foam Mats: Online Measurement Based on Dopant-Assisted Photoionization TOFMS and Assessment of Their Exposure for Children.

Formamide has been classified as a Class 1B reproductive toxicant to children by the European Union (EU) Chemicals Agency. Foam mats are a potential source of formamide and ammonia. Online dopant-assisted atmospheric pressure photoionization time-of-flight mass spectrometry (DA-APPI-TOFMS) coupled with a Teflon environmental chamber was developed to assess the exposure risk of formamide and ammonia from foam mats to children. High levels of formamide (average 3363.72 mg/m3) and ammonia (average 1586.78 mg/m3) emissions were measured from 21 foam mats with three different raw material types: ethylene-vinyl acetate (EVA: n = 7), polyethylene (PE: n = 7), and cross-linked polyethylene (XPE: n = 7). The 28 day emission testing for the selected PE mat showed that the emissions of formamide were 2 orders of magnitude higher than the EU emission limit of 20 µg/m3, and formamide may be a permanent indoor contaminant for foam mat products during their life cycle. The exposure assessment of children aged 0.5-6 years showed that the exposure dose was approximately hundreds of mg/kg-day, and the age group of 0.5-2 years was subject to much higher dermal exposures than others. Thus, this study provided key relevant information for further studies on assessing children's exposure to indoor air pollution from foam mats.

A dual-emitting Tb(iii)&Yb(iii)-functionalized coordination polymer: a "turn-on" sensor for N-methylformamide in urine and a "turn-off" sensor for methylglyoxal in serum.

Fluorescent materials with lanthanide cations encapsulated in MOFs are currently used in numerous applications, especially in biosensors. Therefore, herein, two novel composites were designed and developed based on a Tb(iii)&Yb(iii)-functionalized Cu(ii)-coordination polymer, possessing higher thermal and water stability and fascinating fluorescence properties. The first bimetallic composite Tb@Cu-Hcbpp demonstrated broad ligand-centered emission and weak typical Tb3+ ion emission; moreover, it was used as an excellent ratiometric fluorescent sensor for the metabolic product NMF of DMF in the human body (LOD = 0.02 µM). In addition, the Yb3+ ions were doped into Tb@Cu-Hcbpp to improve the fluorescence performance of the green Tb3+ ion emission. Among the series of Tb1-xYbx@Cu-Hcbpp samples (x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35 and 0.40), Tb0.85Yb0.15@Cu-Hcbpp showed maximum enhanced fluorescence intensity (almost 9.6 times that of the pure terbium system), but exhibited high fluorescence quenching efficiency for methylglyoxal (MGO), which could be used for the sensitive detection of MGO (LOD = 0.25 µM). Furthermore, the developed biosensors were successfully applied for the detection of NMF and MGO in urine and serum samples, and satisfactory results were obtained, showing good potential of these biosensors in practical applications such as in disease diagnosis and biochemical research.

Marker-Independent In Situ Quantitative Assessment of Residual Cryoprotectants in Cardiac Tissues.

Cryomedium toxicity is a major safety concern when transplanting cryopreserved organs. Therefore, thorough removal of potentially toxic cryoprotective agents (CPAs) is required before transplantation. CPAs such as dimethyl-sulfoxide (DMSO), propylene glycol (PG), and formamide (FMD), routinely employed in ice-free cryopreservation (IFC), have advantages in long-term preservation of tissue structures compared with conventional cryopreservation employing lower CPA concentrations. This study evaluated the impact of potential residual CPAs on human cardiac valves. Raman microspectroscopy and Raman imaging were established as nondestructive marker-independent techniques for in situ quantitative assessment of CPA residues in IFC valve tissues. In detail, IFC valve leaflets and supernatants of the washing solutions were analyzed to determine the washing efficiency. A calibration model was developed according to the CPA's characteristic Raman signals to quantify DMSO, PG and FMD concentrations in the supernatants. Single point Raman measurements were performed on the intact tissues to analyze penetration properties. In addition, Raman imaging was utilized to visualize potential CPA residues. Our data showed that washing decreased the CPA concentration in the final washing solution by 99%, and no residues could be detected in the washed tissues, validating the multistep CPA removal protocol routinely used for IFC valves. Raman analysis of unwashed tissues showed different permeation characteristics depending on each CPA and their concentration. Our results demonstrate a great potential of Raman microspectroscopy and Raman imaging as marker-independent in situ tissue quality control tools with the ability to assess the presence and concentration of different chemical agents or drugs in preimplantation tissues.

Aroma compositions of large-leaf yellow tea and potential effect of theanine on volatile formation in tea.

Large-leaf yellow tea (LYT) imparting unique toasty flavor is a traditional beverage in China. The volatile composition of LYT after full fire processing (FF-YT) was determined by different extraction methods. Steam distillation (SD), solid-phase microextraction (SPME) and headspace (HS) were applied for analysis of tea body notes, tea infusion and dry tea aroma, respectively. A total of 143 volatile compounds was identified by the three methods, of which SD-FF-YT, SPME-FF-YT, and HS-FF-YT extracts contained 100, 72, and 56 volatiles, respectively. Heterocyclics and aromatic compounds were the main volatile composition of LYT and might be contributors to its crispy-rice-like odor. l-Theanine was demonstrated to contribute to the formation of tea volatiles. N-Ethylacetamide, formed in the l-theanine only model thermal reaction, was probably involved in the LYT volatile formation. The current results provide new insight into l-theanine on aroma formation, although the detailed formation mechanism remains largely unknown.

Molybdenum(VI)-Catalyzed Rearrangement of Prebiotic Carbohydrates in Formamide, a Candidate Prebiotic Solvent.

It has been four decades since formamide was first suggested to perform roles as a precursor and/or a solvent in prebiotic chemistry. However, little work has sought to integrate formamide into larger prebiotic schemes that might create prebiotic RNA, often proposed to have been the first Darwinian biopolymer. Here, we report that formamide can be used as a solvent to perform the Bílik reaction, which uses molybdenum(VI) oxo species as catalysts at near-neutral pH to rearrange branched carbohydrates to give linear carbohydrates; the branched carbohydrates are produced from formaldehyde (HCHO) in alkaline mixtures containing borate, whereas the linear carbohydrates are the precursors needed for ribonucleosides and ribonucleotides. Under conditions wherein the Bílik reaction does this rearrangement, carbohydrate reaction products do not require stabilization by borate. These results, therefore, connect aqueous and formamide-based processes for the prebiotic formation of RNA components. Based on data from Hadean zircons that show that the mantle of the early Earth was near the fayalite-quartz-magnetite fugacity, molybdenum in its 6+ oxidation state was likely available in the Hadean. Together, these allow us to conjecture a process that delivers ribonucleosides and ribonucleotides from hydrogen cyanide and HCHO from a Hadean atmosphere on a Hadean geosphere, without needing precisely timed transitions from one solvent system to the other.

Cross-sectional study on N,N-dimethylformamide (DMF); effects on liver and alcohol intolerance.

PURPOSE: There are still concerns regarding occupational exposure to hepatotoxic DMF. This study was designed to evaluate possible liver damaging effects of DMF under current workplace conditions in synthetic fibres industries. METHODS: Among other laboratory parameters, liver function parameters (alkaline phosphatase (ALP), aspartate aminotransferase, alanine aminotransferase and gamma-glutamyltransferase), the mean corpuscular erythrocyte volume (MCV) and carbohydrate-deficient transferrin (CDT) of the workforce of two companies present at the days of study were investigated. Internal exposure to DMF was assessed via three different biomarkers [sum of N-methylformamide and N-hydroxymethyl-N-methylformamide, N-acetyl-S-(N-carbamoyl)cysteine (AMCC) and 3-methyl-5-isopropylhydantoin (MIH)]. Alcohol consumption was assessed by means of direct ethanol metabolites (ethylglucuronide and ethylsulfate). RESULTS: None of the tested liver enzyme activities showed a positive association with any of the three exposure markers, nor did CDT and MCV. CDT was negatively associated with AMCC and the ALP activity negatively with all three exposure markers. Changes in liver function are seen mainly in conjunction with ethanol consumption but also with increasing body weight and age. MCV was associated with smoking. Almost half of the workers stated to experience alcohol flush reaction. CONCLUSION: The present study indicates that long-term exposure to DMF, which was specified by median urinary AMCC levels of 4.84 mg/g creatinine and DMF haemoglobin adduct levels of 60.5 nmol/MIH/g globin, respectively, does not result in any adverse liver effects. In contrast, these DMF exposure levels still elicit certain alcohol intolerance reactions.

Factors affecting the intramolecular decomposition of hexamethylene triperoxide diamine and implications for detection.

Hexamethylene triperoxide diamine (HMTD) is an easily synthesized and highly sensitive organic peroxide frequently used as a primary explosive. The vapor pressure of HMTD is very low, impeding vapor detection, especially when compared to other peroxide explosives, such as triacetone triperoxide (TATP) or diacetone diperoxide (DADP). Despite this fact, HMTD has a perceptible odor that could be utilized in the indirect detection of HMTD vapor. Headspace measurements above solid HMTD samples confirm that HMTD readily decomposes under ambient conditions to form highly volatile products that include formic acid, ammonia, trimethylamine and formamides. The presence and quantity of these compounds are affected by storage condition, time, and synthetic method, with synthetic method having the most significant effect on the content of the headspace. A kinetic study of HMTD decomposition in solution indicated a correlation between degradation rate and the presence of decomposition species identified in the headspace, and provided further insight into the mechanism of decomposition. The study provided evidence for a proton assisted decomposition reaction with water, as well as an intramolecular decomposition process facilitated by the presence of water.

Emissions of amides (N,N-dimethylformamide and formamide) and other obnoxious volatile organic compounds from different mattress textile products.

The emission rates of N,N-dimethylformamide (DMF), formamide (FAd), and certain hazardous volatile organic compounds (VOCs) were measured from seventeen mattress textile samples with four different raw material types: polyurethane (PU: n=3), polyester/polyethylene (PE: n=7), ethylene vinyl acetate (EV: n=3), and polyvinyl chloride (PC: n=4). To simulate the emissions in a heated room during winter season, measurements were made under temperature-controlled conditions, i.e., 50°C by using a mini-chamber system made of a midget impinger. Comparison of the data indicates that the patterns were greatly distinguished between DMF and FAd. PU products yielded the highest mean emission rates of DMF (2940 µg m(-2)h(-1): n=3) followed by PE (325 µg m(-2)h(-1): n=7), although its emission was not seen from other materials (EV and PC). In contrast, the pattern of FAd emission was moderately reversed from that of DMF: EV>PC>PE>PU. The results of our analysis confirm that most materials used for mattress production have the strong potential to emit either DMF or FAd in relatively large quantities while in use in children׳s care facilities, especially in winter months. Moreover, it was also observed that an increase in temperature (25°C to 50°C) had a significant impact on the emission rate of FAd and other hazardous VOCs. In addition to the aforementioned amides, the study revealed significant emissions of a number of hazardous VOCs, such as aromatic and carbonyl compounds.

Occupational exposure to N,N-dimethylformamide in the summer and winter.

We evaluated total body burden of N,N-dimethylformamide (DMF) taken through the lung and skin by personal exposure of workers to DMF and urinalysis of N-methylformamide (NMF) and N-acetyl-S(N-methylcarbamoyl)-cysteine (AMCC). A total of 270 workers were engaged in four different jobs in a workplace distant from main production lines emanating high levels of DMF. They were not required to wear any personal protective equipment including respirators or gloves. We found that log-transformed urinary levels of NMF and AMCC increased with an increase in log-transformed concentrations of exposure to DMF. Urinary levels of NMF and AMCC were significantly higher in the summer than the winter, although there was no significant seasonal difference in the concentrations of exposure to DMF. Our findings suggested that the increased urinary levels of NMF and AMCC in the summer resulted in increased skin absorption of DMF due to an increased amount of DMF absorbed by the moisturized skin under humid and hot conditions. Seasonal changes in the relative internal exposure index confirmed the present finding of enhanced summertime skin absorption of DMF. AMCC is thought to be a useful biomarker for assessments of cumulative exposure to DMF over a workweek and for evaluations of workers' health effects.

Nitrogen dynamics and removal in a horizontal flow biofilm reactor for wastewater treatment.

A horizontal flow biofilm reactor (HFBR) designed for the treatment of synthetic wastewater (SWW) was studied to examine the spatial distribution and dynamics of nitrogen transformation processes. Detailed analyses of bulk water and biomass samples, giving substrate and proportions of ammonia oxidising bacteria (AOB) and nitrite oxidising bacteria (NOB) gradients in the HFBR, were carried out using chemical analyses, sensor rate measurements and molecular techniques. Based on these results, proposals for the design of HFBR systems are presented. The HFBR comprised a stack of 60 polystyrene sheets with 10-mm deep frustums. SWW was intermittently dosed at two points, Sheets 1 and 38, in a 2 to 1 volume ratio respectively. Removals of 85.7% COD, 97.4% 5-day biochemical oxygen demand (BOD(5)) and 61.7% TN were recorded during the study. In the nitrification zones of the HFBR, which were separated by a step-feed zone, little variation in nitrification activity was found, despite decreasing in situ ammonia concentrations. The results further indicate significant simultaneous nitrification and denitrification (SND) activity in the nitrifying zones of the HFBR. Sensor measurements showed a linear increase in potential nitrification rates at temperatures between 7 and 16 degrees C, and similar rates of nitrification were measured at concentrations between 1 and 20mg NH(4)-N/l. These results can be used to optimise HFBR reactor design. The HFBR technology could provide an alternative, low maintenance, economically efficient system for carbon and nitrogen removal for low flow wastewater discharges.

Efficiency evaluation of the main multiresidue methods used in Europe for the analysis of amitraz and its major metabolites.

This paper compares the performance of the three most widely employed multiresidue methods [quick, easy, cheap, effective, rugged, and safe (QuEChERS), mini-Luke, and ethyl acetate] currently used for the determination of amitraz residues in fruits. A fast and differentiated analysis of amitraz and its two main metabolites, N-2,4-dimethylphenyl-N-methylformamidine and 2,4-dimethylformanilide, was performed by HPLC-electrospray ionization-MS/MS using a triple quadrupole mass spectrometer in the positive mode. A test of the stability of the standard solutions showed a rapid hydrolysis of amitraz to the amide and amidine derivatives in solutions containing water, including QuEChERS extracts of crops that were previously acidified. Two useful mass transitions were used to confirm the presence of each analyte in the sample extracts. LOD values ranging from 0.4 to 2.0 microglkg were obtained. Linearity of response over 2 orders of magnitude was demonstrated (r2 > 0.999) in solvent and pear extract. The recovery studies were performed on pear blanks spiked at two concentration levels, 50 and 500 microg/kg (n = 5). Best recoveries, ranging from 75 to 103%, were obtained by the application of the QuEChERS method with CV < 8% in all cases. The QuEChERS method was applied to a monitoring study carried out by the Chemical and Veterinary Investigation Office Stuttgart laboratory. From the 63 pear samples analyzed, 21 contained amitraz residues (expressed as sum) ranging from 0.02 to 2.9 mg/kg. Amitraz parent was detected only in a few cases at very low concentration levels, with N-2,4-dimethylphenyl-N-methylformamidine being the metabolite almost entirely representing the total residue. These results emphasize that the residue situation is clearly underestimated if only the parent compound is targeted, and they reinforce how important it is to include amitraz in the target scope of pesticide residue laboratories, especially since the concentrations detected exceeded the Acute Reference Dose in the majority of cases and pose a health risk to the consumer.

Co-exposure to noise, N,N-dimethylformamide, and toluene on 24-hour ambulatory blood pressure in synthetic leather workers.

Independent exposure to noise, N,N-dimethylformamide (DMF), or toluene has been associated with cardiovascular effects, but the combined effects are not clear. This study investigated ambulatory systolic blood pressure (SBP) and diastolic blood pressure (DBP) in workers co-exposed to noise, DMF, and toluene. Twenty workers in a synthetic leather manufacturing company were recruited as study subjects. Personal noise exposure and ambulatory blood pressure were measured concomitantly for 24 hr; airborne co-exposure to DMF and toluene during the working period was also analyzed to identify solvents exposure. Linear mixed-effects regressions were used to estimate effects on ambulatory blood pressure by controlling potential confounders. Four high-combined-exposure workers (83 +/- 8 dBA; DMF: 3.23 +/- 2.15 ppm, toluene: 1.09 +/- 1.13 ppm) had the higher means of 16 +/- 7 mmHg in 24-hr DBP (p = 0.027) and 21 +/- 8 mmHg in working-time DBP (p = 0.048) than seven low-combined-exposure workers (73 +/- 12 dBA; DMF: 0.41 +/- 0.02 ppm, toluene: 0.12 +/- 0.01 ppm). Three high-noise-exposure workers (84 +/- 7 dBA) also had a marginal increase of 13 +/- 6 mmHg in DBP at work (p = 0.076) compared with the control group. No significant differences in SBP and DBP were found between six high-solvent-exposure workers (DMF: 1.24 +/- 1.25 ppm, toluene: 2.63 +/- 1.29 ppm) and office workers during any periods. After the Bonferroni correction, there were no significant differences in ambulatory blood pressure between three high-exposure groups and the low-exposure groups. Our findings suggest no interactive effects of co-exposure to noise, DMF, and toluene on workers' ambulatory blood pressure.

Impact of N,N-dimethylformamide from domestic effluents on river waters.

The impacts of N,N-dimethylformamide (DMF) from domestic effluents on rivers were evaluated. The hourly DMF concentrations in the inflows (0.21-0.52 mug/L in mean) and the outflows (0.18-0.62 mug/L in mean) of two sewage treatment plants did not show any characteristic variations, and DMF was not removed at both plants. The monthly variations of DMF in the outflows of four sewage treatment plants (0.16-0.62 mug/L in mean) and three rivers (0.06-0.11 mug/L in mean) into which the outflows of the plants were discharged did not show any significant variations. The domestic DMF load per person was calculated to be 0.25 mg/d/person. The percent DMF loads of domestic effluents in the rivers were estimated to be below (8%-32%).

Environmental monitoring of occupational exposure to N,N-dimethylformamide: comparison between active and diffusive sampling.

OBJECTIVES: The objective of this study is to optimize the evaluation of the exposure to N,N-dimethylformamide (DMF) in synthetic leather factories by diffusive samplers. The DMF exposure was monitored in synthetic leather factories by two sampler types: active and diffusive. METHODS: Air measurements were carried out using two different personal air samplers, a diffusive and an active one. The diffusive sampling method, TK200 with charcoal filters, was examined in comparison with pumping through NIOSH silica gel tubes workplace air as with the currently available "gold standard". The evaluation was carried out, in two different years but in the same season, for all the duration of the shift, i.e. 8 h on workers employed in five different factories in the district of Florence and Prato (Italy). RESULTS: The statistical and graphical analysis of data show a good correlation between active and passive samplers (r = 0.96, P < 0.001, n = 91), a good linear regression (DMF(diffusive )= 0.95 DMF(active) + 0.15, R (2) = 0.92), a not statistically significant difference between data (tested by paired t test and non-parametric Wilcoxon test). Moreover, all these results are confirmed for data lower and higher than TLV-TWA, in particular we found a significant Pearson correlation (r = 0.92, P < 0.001, n = 83; r = 0.92, P < 0.05, n = 8, respectively) and a significant linear regression (DMF(diffusive )= 0.88 DMF(active) + 0.73, R (2 )= 0.86; DMF(diffusive )= 0.90 DMF(active) + 3.76, R (2 )= 0.85). Besides, the analysis of graphical representations confirmed the previous evidences. Finally, we can not find a significant difference between different types of job. CONCLUSIONS: Due to the good agreement between the two groups of data, the TK200 samplers can be considered as a simpler approach than the pump for screening worker exposures to DMF.

Development of an analytical method for the evaluation of N,N-dimethylformamide in dosage form design.

N,N-Dimethylformamide (DMF) is a well-known chemical entity that is extensively used for pharmaceutical, biomedical and chemical applications. Previous research identified the need for the development of an effective dosage form for the systemic delivery of DMF due to its unique antiviral properties. For purposes of quality control and evaluation during pharmaceutical product development, development of an analytical method was required. A gas chromatographic (GC) method was developed with a flame-ionization detector (FID) on a carbowax packed glass column. 2-Methoxyethanol was used as internal standard. The analytical method proved to be capable of separating DMF and 2-methoxyethanol adequately within a relatively short runtime of 2.5 min. The analytical method described was primarily developed for use in dissolution studies of DMF containing delivery systems. Various physicochemical properties of candidate internal standard materials were correlated with the observed retention times of these compounds. The best correlation (r2 = 0.8077) was obtained between the boiling point and the retention time of the compounds for the current application. The boiling point of an internal standard candidate material may thereforebe useful in predicting the retention time of that compound under similar conditions.

Development of a solid phase microextraction-gas chromatography method to determine N-hydroxymethyl-N-methylformamide and N-methylformamide in urine.

A headspace solid phase microextraction (SPME) method has been developed to determine metabolites of dimethylformamide, N-hydroxymethyl-N-methylformamide, and N-methylformamide (NMF) as NMF in urine by gas chromatography with nitrogen-phosphorus detector (GC-NPD). An SPME holder with a 65-microm PDMS/DVB fiber coating was used. Optimal desorption conditions were 250 degrees C for 1 min, adsorption at 80 degrees C for 15 min, and 3.00 mL of sample in the headspace vial. The method presented good resolution, repeatability, recovery, detection limit, ruggedness and response linearity.

Tandem mobility mass spectrometry study of electrosprayed tetraheptyl ammonium bromide clusters.

Multiply charged electrospray ions from concentrated solutions of Heptyl4N+Br- (designated A+B- hereafter) in formamide are analyzed mass spectrometrically (MS) following mobility selection in ambient air in a differential mobility analyzer (DMA). Most of the sharp mobility peaks seen are identified as (AB)(n)A+ clusters, with 0 < or = n < ot = 5. One anomalously abundant and mobile ion is identified as NH4+(AB)4. Six ions in the (AB)n(A+)2 series are also identified, completing and correcting earlier mobility data for singly and doubly charged ions up to masses of almost 9000 Da. The more mobile of two broad humps seen in the mobility spectrum includes m/z values approximately from 2500 up to 12,000 Da. It is formed primarily by multiply charged (AB)n(A+)z clusters with multiple ammonium bromide adducts. Because of overlapping of many peaks of different m/z and charge state z, only a few individual species can be identified by MS alone in this highly congested region. However, the spectral simplification brought about by mobility selection upstream of the MS reveals a series of broad modulations in m/z space, with all ions resolved in the second, third, ...sixth modulation being in charge states z = 2, 3, ...6, respectively. Extrapolation of this trend beyond the sixth wave fixes the ion charge state (in some cases up to z = 15) and mass (beyond m = 175,000 u). This wavy structure had been previously observed and explained in terms of ion evaporation kinetics from volatile drops, though without mass identification. All observations indicate that the clusters are formed as charged residues, but their charge state is fixed by the Iribarne-Thomson ion evaporation mechanism. Consequently, the measured curve of cluster diameter versus z yields the two parameters governing ion evaporation kinetics. Clusters with z > 1 and electrical mobility Z > 0.495 cm2/V/s are metastable and evaporate a singly charged cluster, probably (AB)2A+, between the DMA and the MS. Plotting the electrical mobilities Z of the clusters in the form (z/Z)1/2 versus m(1/3) (both proportional to cluster diameter) collapse the data for all cluster sizes and charge states into one single straight line for Z below 0.495 cm2/V/s. This linear relation reveals a uniform apparent cluster density of 0.935 g/cm3 and an effective hard-sphere diameter of the air molecules of 0.44 nm. An anomalous mobility increase is observed at diameters below 3 nm.

The use of biomarkers of exposure of N,N-dimethylformamide in health risk assessment and occupational hygiene in the polyacrylic fibre industry.

BACKGROUND: N,N-dimethylformamide (DMF) was recently prioritised for field studies by the National Toxicology Program based on the potency of its reproductive toxic effects. AIMS: To measure accurately exposure to DMF in occupational settings. METHODS: In 35 healthy workers employed in the polyacrylic fibre industry, N-methylformamide (NMF) and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) in urine, and N-methylcarbamoylated haemoglobin (NMHb) in blood were measured. Workplace documentation and questionnaire information were used to categorise workers in groups exposed to low, medium, and high concentrations of DMF. RESULTS: All three biomarkers can be used to identify occupational exposure to DMF. However, only the analysis of NMHb could accurately distinguish between workers exposed to different concentrations of DMF. The median concentrations were determined to be 55.1, 122.8, and 152.6 nmol/g globin in workers exposed to low, medium, and high concentrations of DMF, respectively. It was possible by the use of NMHb to identify all working tasks with increased exposure to DMF. While fibre crimpers were found to be least exposed to DMF, persons washing, dyeing, or towing the fibres were found to be highly exposed to DMF. In addition, NMHb measurements were capable of uncovering working tasks, which previously were not associated with increased exposure to DMF; for example, the person preparing the fibre forming solution. CONCLUSIONS: Measurement of NMHb in blood is recommended rather than measurement of NMF and AMCC in urine to accurately assess exposure to DMF in health risk assessment. However, NMF and AMCC are useful biomarkers for occupational hygiene intervention. Further investigations regarding toxicity of DMF should focus on highly exposed persons in the polyacrylic fibre industry. Additional measurements in occupational settings other than the polyacrylic fibre industry are also recommended, since the population at risk and the production volume of DMF are high.