Long-term effects of dinoseb and paraquat,both individually and combined,on embryonic development and hatching success ofFasciola hepatica miracidia

Toxic effects of the herbicides dinoseb and paraquat, both individually and combined, on embryonic development and hatching ofFasciola hepatica miracidia were assessed by exposing the eggs to varying concentrations (0–20 g/ml) of each of the herbicides. The results showed that dinoseb has an LC₅₀ value of 4.3 g/ml, paraquat has an LC₅₀ of 4.9 g/ml and the mixture of both dinoseb and paraquat has an LC₅₀ of 7.1 g/ml. Based on the LC₅₀ values, dinoseb is slightly more toxic than paraquat on the tested organisms. The results also showed that the mixture of dinoseb and paraquat is significantly less toxic than the individual pesticides.Eggs ofF. hepatica cultured in either dinoseb or paraquat both individually and combined showed a delay of embryonic development and hatching of the miracidia. Eggs cultured in 0–2 g/ml of dinoseb, paraquat and their mixture, fully embryonated and hatched within 14–16 days, while eggs cultured in 4–6 g/ml of the same herbicides showed a delay of four days for embryonic development and hatching of their miracidia.     

Effects of different dietary levels of cadmium,lead, copper,and zinc on the vitality of the forest pest insect Lymantria dispar L. (Lymantriidae,Lepid)

Lymantria dispar (gypsy moth) larvae were reared on both a natural diet of oak leaves and an artificial medium contaminated independently with four different metal nitrates. Larvae were contaminated up to pupation either from 1st or 4th instars at four concentrations differing by a factor of 5. The lowest concentration levels were 2 g/g Cd, 4 g/g Pb, 10 g/g Cu, and 100 g/g Zn based on nutrient medium dry weight. Developmental rate, growth, mortality and reproductive success were determined. No-Observed-Effect-Concentrations (NOECs) calculated were dependent on the metal, the parameter investigated and the stage at which exposure commenced. In general, larvae exposed from the 4th instar were less susceptible to metal toxification than those exposed from hatching. Considering all parameters investigated, dietary NOECs were determined to be 2 g/g Cd, 4 g/g Pb, 10 g/g Cu, and 100 g/g Zn.     

Lead exposure in indoor firing ranges

Summary Higher air lead levels (time-weighted average 660, range 112–2238 g/m³) were measured in firing ranges where powder charges were employed than in ranges where air guns were used (4.6, range 1.8–7.2 g/m³); levels in the latter were in turn higher than those in ranges used for archery (0.11, range 0.10–0.13 g/m³) Twenty-two marksmen who used powder charges had significantly increased blood lead levels during the indoor shooting season (before: median 106, range 32–176 g/l; after: 138; range 69–288 g/l; P = 0.0001), while 21 subjects who mainly used air guns displayed no significant increase (before: median 91, range 47–179 g/l; after: 84; range 20–222 g/l). Thirteen archers had significantly lower levels than the pistol shooters before the season (P = 0.006), and showed a significant decrease during the season (before: median 61, range 27–92 g/l; after: 56; range 31–87 g/l; P = 0.04). At the end of the indoor season, there was a significant association between weekly pistol shooting time and blood lead levels.     

Human exposure to volatile halogenated hydrocarbons from the general environment

Summary The objective of this study was to assess individual human exposure to volatile halogenated hydrocarbons (VHH) under normal environmental conditions by means of biological monitoring, i.e. by the measurement of these compounds or their metabolites in body fluids, such as blood, serum, and urine. Blood samples of 39 normal subjects without known occupational exposure to these agents were examined for the occurrence of VHH. The following compounds were present in quantifiable concentrations in 60 to 95% of the blood samples examined: chloroform (median 0.2 g/l; range < 0.1–1.7 g/l), 1,1,1-trichloroethane (median 0.2 g/l; range < 0.1–3.4 g/l), tetrachloroethylene (median 0.4 g/l; range < 0.1–3.7 g/l). Trichloroethylene could be detected in 31% of all blood samples (median < 0.1 g/l; range < 0.1–1.3 g/l). In addition, the levels of trichloroacetic acid (TCA) were determined in serum and 24-h urine samples of 43 and 94, respectively, normal subjects. TCA was present in measurable concentrations in all serum and urine samples examined. The median of the TCA levels in serum was 21.4 g/l (range 4.8–221.2 g/l) and in urine 6.0 g/24 h (range 0.6–261.4 g/24 h). The results are discussed in relation to data from the literature on human exposure to VHH from the general environment, i.e. via air, food, and water. The upper normal limits calculated from the results of this investigation can be used to detect even minor excessive exposures to VHH.     

Short-term exposure of zooplankton to the synthetic pyrethroid,fenvalerate, and its effects on rates of filtration and assimilation of the alga,Chlamydomonas reinhardii

In acute tests of toxicity, two cladocerans,Daphnia galeata mendotae andCeriodaphnia lacustris, and the calanoid,Diaptomus oregonensis, were more sensitive to fenvalerate thanDaphnia magna, the organism used in standard laboratory bioassays. The 48-hr EC₅₀s for each species/stage in order of increasing sensitivity were adultD. magna — 2.52 g/L;D. magna (48-hr old) — 0.83 g/L; adultD. galeata mendotae — 0.29 g/L; adultC. lacustris — 0.21 g/L;D. galeata mendotae (48-hr old) — 0.16 g/L; adultDiaptomus oregonensis — –0.12 g/L. No toxicity was observed when these organisms were exposed to a range of concentrations of the emulsifiable concentrate without fenvalerate (the EC blank).Rates of filtration of the¹⁴C-labelled alga,Chlamydomonas reinhardii byD. galeata mendotae, C. lacustris andD. oregonensis were decreased significantly at sublethal concentrations of fenvalerate after only 24-hr exposure.Ceriodaphnia lacustris showed the greatest sensitivity with rates of filtration significantly decreased at 0.01 g fenvalerate/ L. Concentrations of fenvalerate 0.05 g/L resulted in decreased rates of filtration byD. galeata mendotae. A concentration of 0.10 g fenvalerate/ L caused rates of filtration to increase inD. oregonensis. whereas 0.05 and 0.5 g/L resulted in a decrease in these rates.Rates of assimilation of algae byD. galeata mendotae, C. lacustris andD. oregonensis exposed to similar concentrations of fenvalerate were decreased at concentrations 0.05 g fenvalerate/L. Changes in rates of assimilation were not as sensitive a parameter of toxicity as changes in rates of filtration. The EC blank had no significant effects on rates of filtration or assimilation for all three species.     

Percutaneous absorption of N,N-dimethylformamide in humans

Summary Skin penetration fo N,N-dimethylformamide (DMF) liquid or vapour was studied in volunteers. Exposure to liquid DMF was performed in two ways: in a dipping experiment, one hand was dipped up to the wrist in DMF for 2–20 min, while in a patch experiment, 2 mmol DMF was applied to the skin and allowed to be absorbed completely. The period of exposure to DMF vapour (50 mg · m^–3) was 4 h. The DMF metabolites N-hydroxymethyl-N-methylformamide (MF), N-hydroxymethylformamide (F), and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) were monitored in the urine. Liquid DMF was absorbed through the skin at a rate of 9.4 mg · cm^–2 · h^–1. Percutaneous absorption of DMF vapour depended strongly on ambient temperature and humidity and accounted for 13%–36% of totally excreted MF. The results suggest that skin absorption of liquid DMF is likely to contribute to occupational exposure substantially more than penetration of DMF vapour. The yield of metabolites after transdermal DMF absorption was only half of that seen after pulmonary absorption. Elimination of MF and F but not that of AMCC was delayed, which supports the contention that AMCC should be used instead of MF as the most suitable biomarker of DMF in cases where percutaneous intake can occur.     

Toxicity of seleno-L-methionine, seleno-DL-methionine, high selenium wheat, and selenized yeast to mallard ducklings

The toxicity of four chemical forms of selenium (seleno-L-methionine, seleno-DL-methionine, selenized yeast, and high selenium wheat) was compared in day-old mallard ducklings (Anas platyrhynchos). In the first experiment, in which the basal diet was 75% wheat, survival after 2 weeks was lower for ducklings fed 30 g/g selenium as seleno-L-methionine (36%) than for ducklings fed 30 g/g selenium as seleno-DL-methionine (100%) or 30 g/g selenium from high selenium yeast (88%). The concentration of selenium at 2 weeks in the livers of survivors was similar for ducklings fed 15 g/g selenium as seleno-DL-methionine (12 g/g, wet weight), seleno-L-methionine (11 g/g), and high selenium wheat (11 g/g), but was lower when the selenium came from selenized yeast (6.2 g/g). When fed 30 g/g selenium from the various sources, the selenium concentrations in liver were 20 g/g for seleno-DL-methionine, 19 g/g for seleno-L-methionine, and 9.9 g/g for selenized yeast. In a second experiment, in which the basal diet was a commercial duck feed, survival after 2 weeks was 100% in ducklings fed 30 g/g selenium as seleno-DL-methionine, seleno-L-methionine, or selenized yeast. Selenium concentrations in liver were similar for ducklings fed the 30-g/g selenium diets as the DL or L forms of selenomethionine (27 and 25 g/g), but lower for ducklings fed selenized yeast (13 g/g). The greater toxicity of the L form of selenomethionine was probably related to the palatability or nutritional nature of the wheat-based diet used in experiment 1, but the exact reason for the difference between the DL and L forms is unknown. Biologically incorporated selenium, derived from high selenium wheat, was no more toxic than selenium derived from the two purified forms of selenomethionine, and the selenium in selenized yeast was not as toxic as that in the two forms of selenomethionine.     

Acute and chronic exposure of Dunaliella salina and Chlamydomonas bullosa to copper and cadmium: Effects on growth

Effective copper and cadmium concentrations which limited the growth of two chlorophytes by 50%, EC(50)s, after 96 h of static exposure were determined. EC(50)s were 5.94 gM copper and 4.55 M cadmium for Dunaliella salina, and 0.78 M copper and 0.025 M cadmium for Chlamydomonas bullosa. The relationship of the two cations was synergistic towards the growth of both species. Chronic exposure to 4.5×10^–6 M cadmium or 4.9×10^–4 M copper increased the sensitivity of C. bullosa by 26% and 29% towards cadmium and copper, respectively. Changes in co-tolerance were not observed. Cd-treated D. salina was 50% more tolerant towards this cation, whereas Cu-treated cultures showed extreme sensitivity towards copper and co-sensitivity towards cadmium. Furthermore, the phylogenetic hypothesis, predictive of toxic response, failed to hold at the familial level.This work was submitted by Ioanna Visviki to the Department of Biology of the Graduate School of the City University of New York in partial fulfillment of the requirements of the PhD degree.     

Bromacil and diuron herbicides: Toxicity,uptake, and elimination in freshwater fish

Fathead minnows, 30 days old, were exposed to technical grade bromacil and diuron in flow-through tests to determine acute toxicity. LC₅₀ values for bromacil were 185, 183, 182 and 167 mg/L at 24, 48, 96, and 168 hr, respectively; and for diuron, 23.3, 19.9, 14.2, and 7.7 mg/L at 24, 48, 96, and 192 hr, respectively. Eggs, newly hatched fry, and juvenile fish were continuously exposed to lower concentrations of the herbicides for 64 days. Growth was significantly reduced (p 0.01) at the lowest bromacil exposure of 1.0 mg/L. Therefore, it was not possible to determine a no effect concentration. The no effect concentration for diuron was 33.4 g/L, while the lowest concentration which resulted in adverse effects was 78.0 g/L. Adverse effects at 78.0 g/L were an increased incidence of abnormal or dead fry immediately after hatch (p 0.01) and decreased survival throughout the exposure period (p 0.05). Neither herbicide accumulated significantly in fish tissue, as bioconcentration factors were <3.2 and 2.0 for bromacil and diuron, respectively. Rainbow trout (Salmo gairdneri) injected with radiolabeled bromacil or diuron eliminated over 90% of the radioactivity within 24 hr. Parent compound and metabolites were detected in the aquarium water in both cases. Metabolites of diuron recovered from the water included 3,4-dichloroaniline and several demethylated products.     

Exposure of nursery school children and their parents and teachers to di-n-butylphthalate and butylbenzylphthalate

Objectives: Some phthalates, among them di-n-butylphthalate (DnBP) and butylbenzylphthalate (BBzP), are known reproductive and developmental toxicants in animals and suspected endocrine disruptors in humans. Children are probably the most susceptible to these effects. To obtain an estimate of internal exposure to DnBP and BBzP we compared the excretion of their metabolites in the urine of nursery school children with that of their teachers and parents. Methods: We measured the urinary mono-ester metabolites of DnBP, mono-n-butylphthalate (MnBP), and BBzP, monobenzylphthalate (MBzP), in first-morning voids of 36 children (median age 4.7 years) and 19 adults (37.4 years). Results: In all samples both metabolites were detected. Urinary MnBP concentrations (in microgrammes per litre) of the children and adults were 139 and 91.8 (median), respectively. MBzP concentrations were 22.1 g/l and 12.7 g/l (median), respectively. Concentrations in microgrammes per gramme creatinine for MnBP were 161 for the children and 91.8 for the adults (median). The maximum concentration found for children (2249 g/g) was approximately 15-times higher than that for adults (149 g/g). This maximum value for children was attributed to medication that contained DnBP. If this child was excluded, the maximum concentration was 517 g/g. MBzP concentrations for children and adults were 37.0 g/g and 9.8 g/g (median), respectively. The maximum concentration found for children (193 g/g) was approximately seven-times higher than that for adults (26.7 g/g). Creatinine-adjusted concentrations were significantly higher for children for both MBzP and MnBP (P<0.0001). MnBP and MBzP exposures were found to correlate statistically significantly within the childrens cohort (r=0.723, P<0.001). Within the childrens cohort we found elevated MnBP exposure to be caused by augmented use of skin-care products (P<0.05). Conclusion: We have shown that the internal exposure to MnBP and MBzP in children is approximately two- to four-times higher than in adults. Correlation of internal MnBP with MBzP exposure points to common sources of exposure for both phthalates. DnBP exposure seems, at least in part, to be connected with the use of body/skin care products and certain medications.     

Susceptibility of clinical isolates of campylobacter pylori to 24 antimicrobial and anti-ulcer agents

Forty-nine isolates of Campylobacter pylori were tested for their susceptibility to twenty antibiotics and four anti-ulcer agents by an agar dilution technique. Penicillin and amoxycillin were the most active drugs (MIC₉₀, 0.06 /ml); erythromycin, cefazolin, minocycline, ciprofloxacin, ofloxacin and gentamicin were sligthtly less active (MIC₉₀, 1 g/ml). Moderate activity was found for doxycyclin, rifampin, nitrofurantoin, norfloxacin, pefloxacin, enoxacin, paromomycin, metronidazole and tinidazole. All strains were resistant to trimethoprim (MIC > 512 g/ml). Nalidixic acid (MIC₉₀, > 256 g/ml) and colistin (MIC₉₀, > 64 gg/m1) had little to no activity. Of four anti-ulcer drugs, only bismuth subcitrate showed activity (MIC₉₀, 64 g./ml).Strains resistant to all 4-quinolones were found in patients who had previously received ofloxacin as part of a clinical trial aimed at eradication of C. pylori. These isolates remained susceptible to amoxycillin, tetracyclines and to other classes of antibiotics.Corresponding author.     

Monitoring of Antifouling Booster Biocides in Water and Sedimentfrom the Port of Osaka, Japan

Concentrations of booster antifouling compounds in the port of Osaka, Japan were assessed. Concentrations of Sea-Nine 211 (4,5-dichloro-2-n-octyl-3-isothiazolone), thiabendazole (2-(4-thiazolyl)-benzimidazole), IPBC (3-iodo-2-propynyl butylcarbamate), Diuron (3,4-dichlorophenyl-N, N-dimethylurea), Irgarol 1051 (2-methylthio-4-t-butylamino-6-cyclopropylamino-s-triazine), and M1 (2-methylthio-4-t-butylamino-6-amino-s-triazine) in port water samples were in the range of <0.003–0.004 g L^–1, <0.0008–0.020 g L^–1, <0.0007–1.54 g L^–1, <0.0008–0.267 g L^–1, and <0.0019–0.167 g L^–1, respectively. IPBC was not detected in the water samples, but the concentration of Diuron was higher than any previously reported. The concentrations of Sea-Nine 211, thiabendazole, Diuron, Irgarol 1051, and M1 in sediment samples were in the range of <0.04–2.4 g kg^–1 dry, <0.08–1.2 g kg^–1 dry, <0.64–1350 g kg^–1 dry, <0.08–8.2 g kg^–1 dry, and <0.18–2.9 g kg^–1 dry, respectively. IPBC was again not detected. The levels of Sea-Nine 211, Diuron, and Irgarol 1051 in water and sediment samples were high in a poorly flushed mooring area for small and medium-hull vessels. Levels of Diuron and Irgarol 1051 were highest in summer. The concentration of Sea-Nine 211 in water increased between August and October 2002. Except for M1, increases in the levels of booster biocides in sediment were observed during the study period. The sediment–water partition (Kd) was calculated by dividing the concentrations in sediment by the concentrations in water. The Kd values for Sea-Nine 211, thiabendazole, Diuron, Irgarol 1051, and M1 were 690, 180, 2700, 300, and 870. The Kd value for these alternative compounds was lower than for TBT.     

Absorption,metabolism and elimination of N,N-dimethylformamide in humans

Summary Excretion of N,N-dimethylformamide (DMF) and DMF metabolites N-hydroxymethyl-N-methylformamide (MF), N-hydroxymethyl-formamide (F) and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) has been monitored in the urine of volunteers during and after their 8-h exposure to DMF vapour at a concentration of 10, 30 and 60 mg · m^–3. The pulmonary ventilation in these experiments was typically about 101 · min^–1 and the retention in the respiratory tract was 90%. After exposure to 30 mg DMF · m^–3, the yield of compound determined in the urine represented 0.3% (DMF), 22.3% (MF), 13.2% (F) and 13.4% (AMCC) of the dose absorbed via the respiratory tract. The excretion curves of the particular compounds attained their maximum 6–8h (DMF), 6–8h (MF), 8–14h (F) and 24–34h (AMCC) after the start of the exposure. The half-times of excretion were approximately 2, 4, 7 and 23 h respectively. In contrast to slow elimination of AMCC after exposure to DMF, AMCC was eliminated rapidly after AMCC intake. This discrepancy could be explained by rate-limiting reversible protein binding of a reactive metabolic intermediate of DMF, possibly methylisocyanate.     

Nitrous oxide in blood and urine of operating theatre personnel and the general population

Nitrous oxide (N₂O) was assayed in 676 urine samples and 101 blood samples provided after exposure by operating theatre personnel from nine hospitals. The blood and urine assays were repeated in 25 subjects 18 h after the end of exposure. For 80 subjects, environmental N₂O was also measured during intraoperative exposure. Mean urinary N₂O in the 676 subjects at the end of exposure was 40 g/l (range 1–3805 g/l); in 10 of the 676 subjects, urinary N₂O was in the range 279–3805 g/l (mean 1202 /l). The 98^th percentile was 120 g/l. Mean blood N₂O at the end of exposure, measured in 101 subjects, was 21 g/l (median 16 g/l, range 1–75 g/l). Blood and urine N₂O (1.5 g/l and 4.9 g/l, respectively) in 25 subjects, 18 h after exposure, was significantly higher than in occupationally non-exposed subjects (blood 0.91 g/l, urine 1 g/l). Environmental exposure was significantly related to blood and urinary N₂O (r = 0.59 andr = 0.64, respectively). Blood and urinary N₂O were significantly related to each other (r = 0.71), and were equivalent to about 25% of the environmental exposure level. The mean urinary N₂O of 1202 g/l in 10/676 subjects was not related to environmental exposure in the operating theatre. The highest urinary N₂O levels measured in these 10/676 subjects could be explained by an asymptomatic urinary infection.     

Determination of the urinary metabolites of styrene: estimation of the method evaluation function and evaluation of reference values in Danish subjects

Summary A European study on styrene exposure was initiated in 1989 to evaluate the health effects of environmental and occupational exposure. A part of this study included the development of an analytical method for use in a biological monitoring program. The urinary metabolites of styrene, mandelic acid (MA) and phenyl-glyoxylic acid (PGA) were quantitated by a direct and convenient high-performance liquid chromatography method. Urine samples were diluted with eluent and analysed by HPLC with a C₈ reversed-phase column and a buffer to acetonitrile (9:1) eluent with a counterion added. The detector used was a variable UV dectector and the wavelength was = 210 nm. The method was statistically evaluated by a method evaluation demonstrating no systematic error. The uncertainty was 23.8 mol/l and 11.5 mol/l for MA and PGA, respectively. The limit of detection (LOD) of MA is 71.4 mol/l and the LOD of PGA is 34.5 mol/l, sufficiently low for the measurement of styrene exposure at a low exposure level. The present study indicates that reference values for MA and PGA are low. The fraction of reference values below LOD was 0.80 for MA and 0.66 for PGA; consequently, the reference values were described by a non-parametric one-sided tolerance interval. The 95% one-sided upper tolerance limits calculated for MA and PGA were 31.0 mol/mmol creatinine and 20.1 mol/mmol creatinine, respectively, with the coverage 0.95 ±0.045 for both metabolites. The method has been used for biological monitoring in several studies of environmentally and occupationally exposed subjects in concentrations up to 200 mol/mmol creatinine for MA and 150 mol/mmol creatinine for PGA.     

N,N-dimethylbenzylamine: occupationa exposure,analysis and biological monitoring

Dimethylbenzylamine (DMBA) is used in the production of epoxy resins. The aims of this study were to assess occupational exposure to DMBA and evaluate the usefulness of monitoring the urinary excretion of DMBA and DMBA metabolites as indicators of exposure to DMBA. A sensitive gas chromatographic method for analysis of DMBA in air and in urine has been developed. The detection limit for DMBA in air for a 60-l air sample collected in 10 ml absorption solution was 2 g/m³ and in charcoal tubes, 0.3 g/m³. The detection limit for DMBA in urine was 0.02 mg/l. Ten male workers manufacturing epoxy resin were monitored during a full shift in the working environment and urine samples were collected at the end of exposure. The mean exposure and the highest DMBA concentration observed in air were 18 g/m³ (time-weighted average; range 3–48 g/m³) and 91 g/m³, respectively. The DMBA concentrations in the urine samples were below the detection limit. After reduction of the urine samples the DMBA concentrations in the urine samples were below the detection limit. After reduction of the urine samples the DMBA concentrations (U-SumDMBA) ranged from 0.02 to 0.22 mg/l. There was significant correlation between the exposure to DMBA and the U-SumDMBA. This observation suggests that the U-SumDMBA in urine samples collected at the end of a shift is a useful indicators of occupational exposure to DMBA.     

Toxicity of mercury,copper, nickel,lead, and cobalt to embryos and larvae of zebrafish,Brachydanio rerio

The toxicity of mercury (HgCl₂), copper (CuCl₂: 5 H₂O), nickel (NiSO₄: 6 H₂O), lead (Pb(CH₃COO)₂: 3 H₂O) and cobalt (CoCl₂: 6 H₂O) was studied under standardized conditions in embryos and larvae of the zebrafish,Brachydanio rerio. Exposures were started at the blastula stage (2–4 h after spawning) and the effects on hatching and survival were monitored daily for 16 days. Copper and nickel were more specific inhibitors of hatching than cobalt, lead, and mercury. Nominal no effect concentrations determined from the dose-response relationships (ZEPs, Zero Equivalent Points) for effect on hatching time were 0.05 g Cu/L, 10 g Hg/L, 20 g Pb/L, 40 g Ni/L and 3,840 g Co/L, and those for effect on survival time were 0.25 g Cu/L, 1.2 g Hg/L, 30 g Pb/L, 80 g Ni/L, and 60 g Co/L. The no effect concentrations for Ni, Hg and Pb are consistent with previously reported MATC values for sensitive species of fish. The no effect concentrations for copper are 1–2 orders of magnitude lower than previously reported values. The major reason for the latter discrepancy was considered to be the absence of organics that can complex copper ions in the reconstituted water that we used, which had a hardness of 100 mg/L (as CaCO₃) and a pH of 7.5–7.7. Unexposed controls were started with embryos from different parental zebrafishes and the parental-caused variability in early embryo mortality, median hatching time and median survival time were estimated.     

Urinary chlorophenols in sawmill workers

Summary The concentration of urinary chlorophenol was assayed for 230 sawmill workers. Information on the work tasks was obtained through questionnaires from occupational health centres. The workers were divided into three groups on the basis of the type of exposure: (1) those with skin absorption as the main route, (2) those with skin and respiratory route of equal importance and (3) those with respiratory tract as the main route. The concentrations of urinary chlorophenol were higher in workers with skin absorption as the main route (median concentration: 7.8 mol l^–1; range 0.1 to 210.9 mol l^–1) than in those with both routes of equal importance (1.4 mol l^–1; range 0.1 to 47.8 mol l^–1, P<0.001) or in those with mainly respiratory route (0.9 mol l^–1; range 0.1 to 13.3 mol l^–1, P<0.001). The urinary chlorophenol concentration was below 15 moll^–1 in all workers with the lungs as the main absorption route. In nine out of 112 workers whose main absorption route was the skin, the urinary chlorophenol values were above 50 mol l^–1. Six were loaders when the through-dipping method was used. In two of them urinary chlorophenol concentrations were as high as 170.8 and 210.9 mol l^–1, These results emphasize the need to develop and use simple methods of protection against skin contact with chlorophenols.     

A pilot study of lead and cadmium exposure in young children in Stockholm,Sweden: Methodological considerations using capillary blood microsampling

A capillary blood microsampling technique was tested among urban young children in Stockholm. Blood lead (BPb) and hemoglobin (Hb) concentrations were determined in capillary blood obtained by fingerstick from 41 children, 13–20 months old, and the accompanying parent. The quality control included control for lead (Pb) and cadmium (Cd) contamination of material and equipment used for blood sampling, washing procedures for the hands and fingers to be punctured, comparisons of Pb and Cd concentrations in blood obtained by fingerstick and by brachial vein puncture from the same individuals, analysis of external quality control samples for Pb and Cd in blood together with the collected samples, and evaluation of the analytical performance using linear regression analysis.The results showed that blood sampling material may contaminate the blood samples with amounts of Pb and Cd that would seriously influence the monitoring results in the low concentration range (<100 g Pb/L and <1 g Cd/L). However, it is possible to obtain reliable BPb concentrations (>10 g Pb/L), but not BCd concentrations (<1 g Cd/L), with the capillary blood microsampling technique tested provided that a strict quality control is applied. The sampling procedure tested was well accepted by the children and their parents. The children's median BPb concentration (27 g/L; range 9–73 g/L) was similar to the median BPb concentration of their parents (27 g/L; range 7–74 g/L). However, the correlation between child and parent BPb concentrations was poor (R²=0.20), which may indicate different sources to Pb exposure in children and parents.     

Mechanisms of macrolide resistance in Ureaplasma urealyticum: A study on collection and clinical strains

Ureaplasma urealyticum is considered as a species which is intrinsically sensitive to macrolides (MIC < 1 g/ml). Nevertheless, some of the strains recently isolated in our laboratories showed moderate to high levels of resistance (MICs ranging from 2 g/ml to 100 pg/ml). In particular, a strain (CT28) isolated from a patient with nongonococcal urethritis long treated with erythromycin revealed a MIC > 100 g/ml for this antibiotic. In order to investigate the mechanisms of resistance, strain CT28 and ten clinical and laboratory U. urealyticum strains were compared for the sensitivity to six antibiotics including three macrolides. Moreover the amount of macrolide uptake and the specific antibiotic binding to ribosomes were studied.Strain CT28 was resistant to josamycin, erythromycin, roxithromycin, lincomycin and clindamycin but sensitive to minocycline. When compared to a sensitive strain, strain CT28 showed a six-fold reduction in intracellular macrolide influx and accumulation and a reduction in antibiotic binding to ribosomes. The mechanisms implicated in these differences may be important for macrolide resistance in U. urealyticum.