Exposure to ethylene glycol ethers and spermatogenic disorders in man: a case-control study.

A case-control study was conducted among first time patients at a clinic for reproductive disorders. The study group consisted of 1019 cases, defined as patients diagnosed infertile or subfertile on the basis of a spermiogram and 475 controls who were diagnosed as normally fertile by the same procedure. Possible exposure to ethylene glycol ethers was assessed by the presence of the urinary metabolites methoxyacetic acid (MAA) and ethoxyacetic acid (EAA) respectively for 2-methoxyethanol and 2-ethoxyethanol or their acetates. In total, EAA was detected in 39 cases and six controls, with a highly significant odds ratio of 3.11 (p = 0.004). On the other hand, MAA was only found in one case and two controls. The presence of EAA in urine proved to be strongly associated with exposure to preparations containing solvents, especially paint products, and with some groups of occupations, the most important of which were also directly or possibly connected with paint products. The absence of a significant correlation between the concentration of urinary EAA and the various measures of sperm quality could be explained by the expected latent period between exposure and observed effects. Other temporal aspects of the relation between exposure as judged from the presence of urinary EAA and diagnosis are also discussed.

Acute butylglycol intoxication: a case report.

A rare case of butylglycol intoxication in a suicide attempt is reported. Coma and hypotension were present on admission and severe metabolic acidosis arose subsequently. Forced diuresis and haemodialysis led to an uneventful outcome.

Experimental human exposure to ethylene glycol monomethyl ether.

The uptake of EGME and the urinary excretion of its major metabolite (MAA) was studied in seven male volunteers during experimental exposure to EGME at rest. The exposure concentration was set at 16 mg/m3, the present Threshold Limit Value. A high retention (0.76) remained unchanged during the 4-h exposure period. In combination with a constant pulmonary ventilation and a fixed exposure concentration this resulted in an uptake rate that showed no significant variation in time. The total amount of EGME inhaled corresponded to a dose of only 0.25 mg/kg. During and up to 120 h after the start of the exposure, MAA was detected in the urine. The elimination half-life was on average 77.1 h. The total amount of MAA excreted was calculated by extrapolation and averaged 85.5% of the inhaled EGME. The pharmacokinetic data are compared with those obtained from other human exposure studies to ethylene glycol ethers (EGEE and EGBE).

An improved method for the determination in urine of alkoxyacetic acids.

A sensitive and specific method for the determination in urine of alkoxyacetic acids, the metabolites of ethylene glycol monoalkyl ethers, was developed by combining the advantages of two previously described methods. The acids were determined gas chromatographically as their pentafluorobenzylesters. The alkylation with pentafluorobenzylbromide was performed after dissolving the dry residue of lyophilized urine in methanol. Quantitative derivatization was obtained when the urinary pH was adjusted to pH 7.0, when the reagent concentration was 5% v/v, and when the reaction mixture was heated at 90 degrees C for 3 h. Sample clean-up was performed by adding bidistilled water and the esters were extracted with methylene chloride with high yields (95%). Alkoxyacetic acid concentrations in the range of 0.1 to 200 mg/l could be determined with an average imprecision of +/- 3.5%.

Comparative urinary excretion of ethoxyacetic acid in man and rat after single low doses of ethylene glycol monoethyl ether.

Male rats were given a single oral dose of ethylene glycol monoethyl ether (EGEE), the dose ranging from plausible human exposures (0.5-1 mg/kg) to doses reported in the literature (100 mg/kg). Urinary excretion of ethoxyacetic acid (EAA) and its glycine conjugate was followed up to 60 h after dosing and compared to data of experimentally exposed human volunteers. In rats, the mean elimination half-life of free as well as conjugated EAA was 7.2 h for all doses. EAA was excreted partly as a glycine conjugate (on average 27%), the extent of conjugation being independent of the dose. The conjugation with glycine showed a clearly diurnal variation, the lowest extent being found during the night. The relative amount of EGEE recovered in urine as EAA was only 13.4% for the lowest dose, but increased as the administered dose of EGEE was higher, indicating that EGEE was metabolised at least in two parallel pathways of which one pathway becomes saturated at relatively low doses. In man, urinary excretion of EAA for equivalent low doses of EGEE differed from that in the rat by a longer elimination half-life (mean 42 h), by the absence of EAA conjugates and by a higher recovery.

Survey of ethylene glycol ether exposures in Belgian industries and workshops.

From 1983 onward, 2654 air samples from 336 different plants from the northern part of Belgium were analyzed for the presence of ethylene glycol ethers. One or more ethylene glycol ethers were detected in 262 air samples (9.9%) covering 78 plants or small establishments (23.2%) from a wide variety of industries. Ethylene glycol ethers were mainly present in establishments or operations where printing pastes, inks, paints and varnishes were used. About one third of the air samples covered various other industries. Car repair shops took a major part of this group. It was not always clear, however, in what precise operation the glycol ethers were involved. The ethylene glycol ethers most frequently identified were ethylene glycol monoethyl ether (EGEE) and its acetate (EGEE-Ac). Furthermore, ethylene glycol monomethyl ether (EGME), its acetate (EGME-Ac), and ethylene glycol monobutyl ether (EGBE) also were present in a large number of air samples. The glycol ethers were not distributed equally among the various groups of operations. Most exposure levels were far below the respective Threshold Limit Value (TLVs) (approximately less than 0.5 x TLV). About 25% of ethylene glycol concentrations, however, were higher than the current TLV. Most of the excursions were slight to moderate, although in selected cases extremely high concentrations were recorded. The majority of air samples revealed complex mixtures of ethylene glycol ethers with other solvents, the glycol ethers often being minor components. The possible implication of these other solvents on glycol ether toxicity and metabolism is discussed.

Ethoxyacetic acid: a metabolite of ethylene glycol monoethyl ether acetate in man.

Urinary excretion of ethoxyacetic acid during and after exposure to ethylene glycol monoethyl ether acetate (EGEE-Ac) was followed up in ten healthy male volunteers. During exposure to EGEE-Ac, ethoxyacetic acid levels appeared with a half life of 2.3 +/- 0.1 h. Ethoxyacetic acid excretion continued to increase after exposure was discontinued reaching maximal levels three to four hours later. The decline afterwards could generally be described assuming a half life of 23.6 +/- 1.8 h. A second maximum excretion of ethoxyacetic acid, however, was noticed about three hours after the first. Redistribution of EGEE-Ac or ethoxyacetic acid, or both, from a peripheral compartment to the central compartment could explain this observation. Ethoxyacetic acid excretion increased with an increase in the uptake of EGEE-Ac due to higher exposure concentrations or pulmonary ventilation rate during physical exercise. On average 22.2 +/- 0.9% of the absorbed EGEE-Ac was recovered within 42 hours. Recovery did not change with a higher intake of EGEE-Ac. At any time after the exposure, quantitative relations between ethoxyacetic acid excretion rate and absorbed dose of EGEE-Ac were found. Monitoring ethoxyacetic acid excretion may therefore be used as a measure of a single exposure to EGEE-Ac.

Field study of the urinary excretion of ethoxyacetic acid during repeated daily exposure to the ethyl ether of ethylene glycol and the ethyl ether of ethylene glycol acetate.

The urinary excretion of ethoxyacetic acid (EAA) was studied in a group of five women daily exposed to the ethyl ether of ethylene glycol (EGEE) and the ethyl ether of ethylene glycol acetate (EGEE-Ac) during 5 d of normal production and 7 d after a 12-d production stop. The mean combined exposure concentration of EGEE and EGEE-Ac (expressed in equivalent weight of EGEE) was 14.0 mg/m3 with occasional slight excursions above the current Belgian occupational exposure limit. The daily combined exposure profiles for EGEE and EGEE-Ac were rather constant during the first observation period, but they tended to decrease during the last week. The urinary EAA excretion clearly increased during the work week. Over the weekends the elimination was far from complete, and even after a prolonged nonexposure period of 12 d traces of the metabolite were still detectable. Based on the observations from the first period, a good linear correlation (r = 0.92) was found between the average exposure over 5 d (14.4 mg/m3) and the EAA excretion at the end of the week (105.7 mg/g creatinine). An EAA estimate of 150 +/- 35 mg/g was found to correspond with repeated 5-d full-shift exposures to the respective occupational exposure limit of EGEE (19 mg/m3) or EGEE-Ac (27 mg/m3).

Pulmonary absorption and elimination of ethylene glycol monoethyl ether acetate in man.

Ten male volunteers were exposed to ethylene glycol monoethyl ether acetate (EGEE-Ac) under various conditions of exposure and physical workload. As exposure proceeded, retention, atmospheric clearance, and uptake rate declined slowly to reach steady state levels after three to four hours. Retention increased as a consequence of higher exposure concentrations and of physical workload performed during exposure. Uptake rate was higher as exposure concentration or pulmonary ventilation rate, or both, increased. Subject related factors such as pulmonary ventilation, cardiac output, height, and body fat content also determined individual uptake. During exposure, partial respiratory elimination of EGEE was observed. This finding confirms the hypothesis that EGEE-Ac is first converted to EGEE by (plasma) esterases. The amount of EGEE eliminated at steady state levels correlated more with uptake rate of EGEE-Ac than with exposure concentration. Respiratory elimination of unmetabolised EGEE-Ac accounted for less than or equal to 0.5% of total body uptake. The elimination curves were biexponential indicating that at least two pharmacological compartments are involved. Postexposure breath concentrations were higher as total body uptake increased. Several observations may indicate that the hydrolysis of the ester moiety of EGEE-Ac is hindered by the presence of the natural esterase substrates. With increasing plasma concentrations, however, EGEE-Ac competed more favourably for the available esterase.

Urinary excretion of ethoxyacetic acid after experimental human exposure to ethylene glycol monoethyl ether.

Ten healthy male subjects were exposed to ethylene glycol monoethyl ether (EGEE) under various conditions of exposure concentration and physical workload and their urinary excretion of ethoxyacetic acid was followed up for 42 hours. Maximal excretion of ethoxyacetic acid was reached three to four hours after the end of the four hour exposure period. Afterwards, ethoxyacetic acid excretion declined slowly with a biological half life of 21-24 hours. Ethoxyacetic acid excretion increased as the uptake of EGEE increased as a consequence of higher exposure concentration or pulmonary ventilation rate during physical exercise. On average, 23.1 +/- 6.3% of EGEE was recovered as ethoxyacetic acid within 42 hours and the recovery did not change as the uptake of EGEE increased. Quantitative relations between ethoxyacetic acid excretion and EGEE uptake were obtained and the relevance of ethoxyacetic acid excretion as a measure for exposure to EGEE is discussed.

Respiratory uptake and elimination of ethylene glycol monoethyl ether after experimental human exposure.

Ten male volunteers were exposed to ethylene glycol monoethyl ether (EGEE) under various conditions of exposure concentration and physical workload. Steady state levels of retention, atmospheric clearance, and rate of uptake were reached immediately after the start of the exposure period for all experimental conditions. Retention was high (64% in resting condition) and increased as physical exercise was performed during exposure. Atmospheric clearance increased as the pulmonary ventilation rate increased. The rate of uptake was higher as exposure concentration or pulmonary ventilation rate, or both, increased. Individual uptake appeared to be governed mainly by transport mechanisms (pulmonary ventilation or cardiac output or both) and not by anthropometric factors. Respiratory elimination of unchanged EGEE accounted for less than or equal to 0.4% of the total body uptake. Postexposure breath concentrations declined rapidly during the first minutes after cessation of exposure, after which a much slower decrease was observed. This slow decrease could be described by a regression equation containing two exponential terms indicating that at least two pharmacological compartments are concerned.

Gas chromatographic determination of methoxyacetic and ethoxyacetic acid in urine.

Methoxyacetic acid (MAA) and ethoxyacetic acid (EAA), the major metabolites of, respectively, ethylene glycol monomethyl ether and ethylene glycol monoethyl ether and their acetates, are determined by gas chromatography after extraction from urine and methylation using 2-furoic acid (2-FA) as an internal standard. The mean recoveries (n = 30) from urine of MAA, EAA, and 2-FA are 31.4 +/- 7.0%, 62.5 +/- 13.4%, and 58.4 +/- 8.7%, respectively. The recoveries decreased (p less than 0.001), however, as the total amount of acids increased. Standard curves for MAA and EAA in urine are presented. The detection limits of MAA and EAA are 0.15 and 0.07 mg/l. Intra-assay variation for MAA and EAA was 6.0 +/- 2.5% and 6.4 +/- 2.8% and inter-assay variation was 6.2 +/- 2.2% and 8.9 +/- 2.4%. When volunteers were exposed to air containing ethylene glycol monoethyl ether (20 mg/m3), urinary concentration of EAA rose significantly one hour after the exposure period (2.39 +/- 1.03 v less than or equal to 0.07 mg/l, t = 5.2, p less than 0.005).

Plasma levels of renin, angiotensin II, and 6-ketoprostaglandin F1 alpha in endurance athletes.

Twelve male runners and 12 matched nonathletes performed a prolonged uninterrupted graded exercise test on the bicycle ergometer up to exhaustion to study blood pressure and plasma levels of renin (PRA), vasoconstrictor angiotensin II (ANG II), and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha), a metabolite of the vasodilator prostacyclin. In the athletes work load was increased by 30 W/4 min, and in the control subjects the increments of work load were adjusted to their lower exercise capacity to equalize total exercise duration. Blood was drawn, and blood pressure and O2 uptake (VO2) were measured at rest and at the fourth, eighth, and last steps of exercise. Peak VO2 averaged 60 +/- 1.6 ml . min-1 . kg-1 in the runners and 46.8 +/- 1.5 in the nonathletes. To evaluate differences between athletes and controls, PRA, ANG II, and 6-keto-PGF1 alpha were first adjusted for significant confounding factors, such as age, weight, hematocrit, 24-h urinary sodium excretion, and O2 uptake. PRA was significantly lower in the athletes (F = 11.2; P less than 0.01); ANG II was not different at rest, but its rise with exercise was less steep in the runners (F = 8.2; P less than 0.01), whereas 6-keto-PGF1 alpha was not different between the groups (F = 1.3; NS). Despite the differences in PRA and ANG II, however, blood pressure was similar in athletes and nonathletes (F = 0.0; NS).

In vitro inhibition of renal sodium-potassium ATPase activity by progesterone.

The effect of various steroids and prostaglandins on the activity of canine kidney Na+, K+-ATPase activity was tested in vitro. Progesterone induced a dose-dependent increase in inhibition of the canine kidney Na+, K+-ATPase activity. Aldosterone, cortisol, cortisone as well as prostaglandin E2 and 13,14-dihydro-15-keto-prostaglandin F2 alpha, did not cause an inhibition of canine kidney Na+, K+-ATPase.

Active and acid-activable inactive renin during inhibition by indomethacin of prostaglandin synthesis in sodium-replete man.

The effect of inhibition of prostaglandin synthesis by indomethacin on active renin and on acid-activable inactive renin was studied in nine healthy, sodium-replete men, both at rest and exercise. These volunteers were investigated after pretreatment with placebo or indomethacin, 150 mg daily for 3 days. Indomethacin induced a decrease in active (P = 0.004), total (P less than 0.001) and inactive (P = 0.02) renin at rest recumbent and at rest, sitting. Inhibition of prostaglandins with indomethacin reduced (P less than 0.001) active and total renin at each level of work load but not (P = 0.32) inactive renin. However the exercise-induced stimulation (P less than 0.05) of active and of total renin still occur during indomethacin. Indomethacin reduced (P less than 0.001) at rest, sitting and at maximal exercise the plasma concentrations of immunoreactive prostaglandins E2, prostaglandin F2 alpha and 13, 14-dihydro-15-keto-prostaglandin F alpha; the urinary excretion of immunoreactive prostaglandin E2 and F2 alpha were also reduced.

Erythrocyte concentrations and transmembrane fluxes of sodium and potassium and biochemical measurements during the menstrual cycle in normal women.

The erythrocyte concentrations and the transmembrane fluxes of sodium and potassium were investigated in 20 normal women during the two stages of the menstrual cycle. Half of the women were using oral contraceptives and the other half were not. In women with a normal menstrual cycle the erythrocyte sodium concentration and the ouabain-insensitive total potassium efflux were lower in the luteal than in the follicular phase. Intracellular potassium concentration, ouabain-sensitive rubidium 86 uptake and the furosemide-sensitive sodium and potassium efflux did not differ significantly between the two periods of the cycle. No cycle-related variation in sodium or potassium intracellular concentration was observed in women using oral contraceptives. In these women, however, the ouabain-sensitive 86Rb uptake was increased in the second part of the menstrual cycle. In each woman with a normal menstrual cycle the plasma progesterone, renin activity, angiotensin II, plasma aldosterone concentration, and urinary aldosterone excretion increased during the luteal phase. The increment in the plasma renin activity, plasma angiotensin II, and plasma and urinary aldosterone indicate a stimulation of the renin-aldosterone axis in this menstrual period. During the same phase, serum cholesterol was decreased significantly. When the women using oral contraceptives were compared to those not using them, the renin-aldosterone axis was already stimulated during the first part of the cycle; no further stimulation occurred during the second part.

Intracellular concentration and transmembrane fluxes of sodium and potassium in erythrocytes of normal men and women.

The intracellular concentration and transmembrane fluxes of sodium and potassium were studied in the red blood cells of normal men and women in the two halves of their menstrual cycle. Compared to men, the intra-erythrocyte sodium concentration was lower in women during the second half of the menstrual cycle. These two groups were similar for Na+, K+-ATPase pump activity estimated from the ouabain-sensitive 86rubidium-uptake and for the furosemide-sensitive sodium and potassium efflux. Women in the first half of the menstrual cycle, had intra-erythrocyte sodium concentration similar to men, but their furosemide-sensitive sodium efflux was lower. A lower intra-erythrocyte sodium concentration was observed in the second half as compared to the first half of the menstrual cycle in women. No significant difference was observed in the intra-erythrocyte potassium concentration and transmembrane fluxes of potassium in men and women in either half of the menstrual cycle. Therefore one should take into account sex-related variability when studying cationic fluxes and concentrations in red blood cells of men and women.

Racial differences in intracellular concentration and transmembrane fluxes of sodium and potassium in erythrocytes of normal male subjects.

Erythrocyte concentrations and fluxes of sodium and potassium were investigated in normal black and white male subjects. Erythrocyte sodium concentration was significantly elevated in blacks compared to whites. In single regression analysis erythrocyte sodium concentration was inversely related to the ouabain-sensitive 86Rb-uptake and to the frusemide-sensitive sodium efflux. After adjusting for race, only the relationship between the erythrocyte sodium concentration and the Na+, K+-ATpase pump activity persisted. The sodium-lithium countertransport system was also depressed in the black subjects. No significant difference was observed in erythrocyte potassium concentration between blacks and white. It is probable that, in blacks the decreased active influx of potassium through the sodium-potassium pump was to some extent counter balanced by a reduced efflux of this cationic mediated by the depressed cotransport system. There was no difference in cationic concentrations and fluxes of sodium and potassium between blacks bearing and not bearing haemoglobin S.

Assessment of sodium-potassium ATPase activity in human erythrocytes in vitro.

The red cell Na+,K+-ATPase pump activity was measured either by the ouabain-sensitive 86Rb-uptake in the presence or absence of 4 mM potassium in the external medium or by the ouabain-sensitive Na+-efflux in normal male subjects without any medication (n = 14) and during short-term treatment with the serotonin-antagonist, ketanserin. The ouabain-sensitive 86Rb-uptake in a medium containing 4 mM K+ was related to the 86Rb-uptake in a K+-free medium (r = 0.82; p less than 0.001) and to the Na+ efflux (r = 0.74; p less than 0.01). The intra-erythrocyte sodium concentration was negatively related to the ouabain-sensitive 86Rb-uptake (K+-free medium r = 0.59, p less than 0.05: 4 mM K+ in medium r = -0.85; p less than 0.01) and to the ouabain-sensitive Na+ efflux (r = -0.53; p less than 0.05). During serotonin antagonism with ketanserin no changes were found in the ouabain-sensitive 86Rb-uptake or Na+-efflux.

Methodological assessment of assays for intracellular concentration and transmembrane fluxes of sodium and potassium in erythrocytes of man.

The reliability of the assay of intracellular Na+ and K+ concentration; Na+,K+-ATPase activity; Na+-K+ cotransport and Na+-Li+ countertransport in erythrocytes was investigated. These assays were also applied in normal male subjects with and without family history of hypertension. The various assays are reproducible as indicated by the intra-assay variation and are stable over time as shown by the inter-assay variation. A delay between blood sampling and analysis, however, result in an increase in intracellular Na+ concentration and decreases in Na+,K+-ATPase activity; Na+-K+ cotransport and Na+-Li+ countertransport. Compared to the white normal males without family history of hypertension (n = 43) red blood cells of white normal males with such a history (n = 17) have a higher (p less than 0.01) intracellular Na+ concentration. This can be at least partly due to their lower (p less than 0.001) furosemide-sensitive Na+ efflux rate. Also, their ouabain-resistant 86Rb-uptake was lower (p less than 0.05). The potassium concentration in the red blood cells was similar in both groups.