The effects of prenatal cocaine exposure and gender on inhibitory control and attention

Children exposed prenatally to cocaine show deficits in emotion regulation and inhibitory control. While controlling for the measures of medical complication in the perinatal period, environmental risk, and prenatal polydrug exposure (alcohol, tobacco, and marijuana), we examined the effects of prenatal cocaine exposure and gender on attention and inhibitory control in 203 children at ages 6, 9, and 11. Cocaine exposure affected the performance of males, but not females. Heavily exposed males showed deficits in the attention and the inhibition tasks. In addition, a significantly greater proportion of heavily exposed males (21%) than unexposed males (7%) or heavily exposed females (7%) failed to complete the task (p < 0.01). Even without those poorest performing subjects, the overall accuracy for heavily exposed males (81%) was significantly reduced (p < 0.05) compared to lightly exposed males (87%) and unexposed males (89%). The findings highlight the importance of considering gender specificity in cocaine exposure effects. Processes by which cocaine effects may be specific to males are discussed.     

The risk of occupational exposure to mercury vapor in some public dental clinics of Baghdad city,Iraq

Background: Dental workers are exposed to elevated levels of elemental mercury vapor substantially above the occupational exposure standards when placing or removing mercury/silver tooth restorations and disposing of mercury waste. This results in a significant increase in occupational exposure and risk of mercury intoxication.

Methods: To evaluate the occupational exposure of dental workers to amalgam in four dental clinics in Baghdad city, the concentrations of mercury vapor were measured seasonally from February to November 2016. Samples of blood and urine were collected from 30 dental workers (exposed individuals) and five non-occupationally exposed individuals. Biochemical parameters such as cholesterol, liver enzymes (alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase), renal enzymes (urea and creatinine), total protein and reduced glutathione (GSH) were observed.

Results: The results indicated that mercury vapor levels varied from 84.7?±?18.67 to 609.3?±?238.90?µg/m³ and most concentrations were above the occupational exposure standards. The results of the biochemical parameters showed a significant increase in levels of cholesterol, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and no significant increase in blood urea and creatinine in dental workers in comparison with unexposed persons (control). Although the results showed a significant reduction in the levels of glutathione and total protein, there was no significant decrease in the levels of alkaline phosphatase (ALP) in exposed dental workers when compared with non-occupationally exposed individuals.

Conclusions: It is concluded that mercury vapor concentrations in the indoor air of some dental clinics in Baghdad city are high and exceed the OSHA STEL(Occupational Safety and Health Administration Short Term Exposure Limit). The present data showed that altered biochemical parameters can be used as efficient bioindicators for mercury toxicity.     

Industrial blood lead levels in the South Island during 1988 and 1989: trends and follow up patterns.

AIMS: to assess trends in industrial lead exposure and the monitoring programmes in the South Island of New Zealand. METHODS: during the period 1 January 1988 to 31 December 1989, industrial lead exposure was analysed in 1425 workers in at risk occupations and the efficiency of retesting programmes was determined. RESULTS: forty-four percent of these workers had red cell lead levels above 1.9 mumol/L, the top of the reference range for an unexposed population, and 71 individuals had levels exceeding the recommended action limits (males greater than 5.0 mumol/L, and females greater than 3.8 mumol/L). Although most occupational groups showed a small decline in mean red cell lead levels, the pattern of exposure was similar to previous reports. On average, only 43% of exposed workers were retested within the recommended period and 32% of these workers were not retested within 2 years of having a raised blood lead level. CONCLUSIONS: retesting was inefficient but was most reliable when industrial health nurses were employed for monitoring. Not all lead poisoning comes from the traditional lead based industries and significant decreases were found in workers whose primary exposure is to lead from petrol.     

Inhalation toxicity of epichlorohydrin: Effects on fertility in rats and rabbits

The effects of inhaled epichlorohydrin (ECH) on the fertility of Sprague-Dawley rats and New Zealand white rabbits were studied. Groups of 10 male rabbits, 30 male rats, and 30 female rats were exposed to 0, 5, 25, or 50 ppm of ECH vapor for 6 hr/day, 5 days/week for 10 weeks, and were held for a 10-week postexposure period. Semen from rabbits was evaluated, and the exposed male rabbits were mated with unexposed females. Exposed male rats were mated with unexposed females at several intervals during and after the exposure period. In addition, female rats which had been exposed for the 10-week period were mated with unexposed males and allowed to deliver their young. Exposure to 50 ppm of ECH vapor for 10 weeks resulted in transient infertility in the male Sprague-Dawley rats; recovery of fertility in rats occurred during the second week after termination of exposure. Male rats exposed to 25 ppm of ECH were able to impregnate unexposed females; however, fewer implantations were observed in these females than in the females mated to control males suggesting that fertility was adversely affected in this group as well. This effect also was reversed by the second week following termination of exposure. The incidence of resorptions in the unexposed female rats which were bred to the exposed males was not adversely affected. Among female rats exposed to ECH, no adverse effects were observed on estrus cycle, pregnancy rate, parturition, or the number and viability of the offspring. No discernible effects were noted on the volume of the ejaculate or on the motility, viability, concentration, or fertility of spermatozoa from male rabbits exposed to up to 50 ppm of ECH. Histologic examination of tissues from an interim and final termination of the exposed animals indicated that the most severely affected organ following inhalation exposure to 25 or 50 ppm of epichlorohydrin in both rats and rabbits was the nasal turbinates. These lesions, interpreted to be a result of irritation from the test material, were no longer present in animals which were held for the 10-week postexposure period. No adverse effects were observed among rats or rabbits exposed to 5 ppm of ECH for 10 weeks.     

Reference values for hair cotinine as a biomarker of active and passive smoking in women of reproductive age, pregnant women, children, and neonates: systematic review and meta-analysis

Exposure to environmental tobacco smoke (ETS) is most often estimated using questionnaires, but they are unreliable. Biomarkers can provide valid information on ETS exposure, the preferred biomarker being cotinine. However, no reference range of hair cotinine exists to distinguish among active, passive, and unexposed nonsmokers. This study identifies cutoffs to validate cotinine as a marker for exposure to ETS. Data were obtained from six databases (four US, one Canada, one France). Active smoking and exposure to ETS were measured in the hair of women of reproductive age, pregnant women, their children, and neonates. Subjects were classified into active smokers, passively exposed to ETS, and unexposed nonsmokers. A total of 1746 cases were available for analysis. For active smokers, mean hair cotinine concentrations (95% confidence interval) were 2.3 to 3.1 ng/mg for nonpregnant women and 1.5 to 1.9 ng/mg for pregnant women. In the group of passive smokers, mean hair cotinine concentrations were 0.5 to 0.7 ng/mg for nonpregnant women, 0.04 to 0.09 ng/mg for pregnant women, 0.9 to 1.1 for children, and 1.2 to 1.7 for neonates. Among unexposed nonsmokers, mean hair cotinine was 0.2 to 0.4 ng/mg in nonpregnant women, 0.06 to 0.09 ng/mg in pregnant women, and 0.3 to 0.4 ng/mg in children. Cutoff values for hair cotinine were established to distinguish active smokers from passive or unexposed (0.8 ng/mg for nonpregnant women and 0.2 ng/mg for pregnant women). A cutoff value of 0.2 ng/mg was accurate in discriminating between exposed children and unexposed. These new values should facilitate clinical diagnosis of active and passive exposure to tobacco smoke. Such diagnosis is critical in pregnancy and in a large number of tobacco-induced medical conditions.     

Primary DNA damage in chrome-plating workers

In order to evaluate the primary DNA damage due to occupational exposure to chromium (VI), DNA strand-breaks and apoptosis in peripheral lymphocytes were measured in a group of 19 chrome-plating workers. DNA strand-breaks was assessed by alkaline (pH>13) single-cell microgel electrophoresis ('comet') assay, while apoptosis was measured by flow-cytometry after propidium iodide staining of the cells. Concentrations of chromium in urine, erythrocytes and lymphocytes were investigated as biological indicators of exposure. A group of 18 hospital workers (control group I) and another 20 university personnel (control group II) without exposure to chromium were also studied as controls. The results of the study show that chrome-plating workers have higher levels of chromium in urine, erythrocytes and lymphocytes than unexposed workers. Comet tail moment values, assumed as index of DNA damage, are increased in chromium-exposed workers and results are significantly correlated to chromium lymphocyte concentrations. No difference emerged in the percentage of apoptotic nuclei in exposed and unexposed workers. The study confirms that measurements of chromium in erythrocytes and lymphocytes may provide useful information about recent and past exposure to hexavalent chromium at the workplace. The increase in DNA strand-breaks measured by comet assay suggests this test is valid for the biological monitoring of workers exposed to genotoxic compounds such as chromium (VI).     

Evaluation of primary DNA damage, cytogenetic biomarkers and genetic polymorphisms for CYP1A1 and GSTM1 in road tunnel construction workers

In tunnel construction workers, occupational exposure to dust (alpha-quartz and other particles from blasting), gases (nitrogen dioxide, NO(2)), diesel exhausts, and oil mist has been associated with lung function decline, induction of inflammatory reactions in the lungs with release of mediators that may influence blood coagulation, and increased risk of chronic obstructive pulmonary disease. The present molecular epidemiology study was designed to evaluate whether occupational exposure to indoor pollutants during road tunnel construction might result in genotoxic effects. A study group of 39 underground workers and a reference group of 34 unexposed subjects were examined. Primary and oxidative DNA damage, sister-chromatid exchanges (SCE), and micronuclei (MN) were measured in peripheral blood cells. The possible influences of polymorphisms in gene encoding for CYP1A1 and GSTM1 xenobiotic-metabolizing enzymes were also investigated. Exposure assessment was performed with detailed interviews and questionnaires. There were no significant differences in the level of primary and oxidative DNA damage and frequency of SCE between the tunnel workers and controls, whereas the frequency of MN showed a significant increase in exposed subjects compared to controls. No effects of CYP1A1 or GSTM1 variants were observed for the analyzed biomarkers. Since MN in peripheral blood lymphocytes are recognized as a predictive biomarker of cancer risk within a population of healthy subjects, the genotoxic risk of occupational exposure to various indoor environmental pollutants during road tunnel construction cannot be excluded by this biomonitoring study.     

200例职业性铅中毒患者肝脾B超检查结果分析

目的：了解长期接触铅所致慢性铅中毒患者肝脾的B超征象。方法选择2008~2012年在本院门诊或住院的200例职业性慢性铅中毒患者为观察组,无职业病危害因素接触的公务员200例为对照组,两组均给予肝脾B超检查并对其检查结果进行比较分析。结果观察组的肝脾B超异常率为23.5%,明显高于对照组的11.5%（P〈0.01）;观察组的肝大检出率为16%,明显高于对照组的6%（P〈0.01）;观察组的左肝长、厚,右肝斜厚均高于对照组（P〈0.01）。结论职业性慢性铅中毒患者肝脾存在一定的损害,应引起重视。     

Assessment of DNA damage in car spray painters exposed to organic solvents by the high-throughput comet assay

Occupational exposure as a painter is associated with DNA damage and development of cancer. Comet assay has been widely adopted as a sensitive and quantitative tool for DNA damage assessment at the individual cell level in populations exposed to genotoxics. The aim of this study was to assess the application of the high-throughput comet assay, to determine the DNA damage in car spray painters. The study population included 52 car spray painters and 52 unexposed subjects. A significant increase in the %TDNA median (p?< 0.001) was observed in the exposed group in comparison to the unexposed group. Neither age (%TDNA: p?= 0.913) nor time of exposure (%TDNA: p?=?0.398) were significantly correlated with DNA damage. The car spray painters who consumed alcohol did not show a significant increase in DNA damage compared to nonalcohol consumers (p >?0.05). The results showed an increase in DNA breaks in car spray painters exposed to organic solvents and paints; furthermore, they demonstrated the application of high-throughput comet assay in an occupational exposure study to genotoxic agents.     

Inhalation fertility and reproduction studies with O,O′-dimethylphosphorodithioate in Sprague-Dawley rats

Groups of 15 male and 35 female Sprague-Dawley rats were exposed to O,O′-dimethylphosphorodithioate (DMPDT) 6 hr/day, 5 days/week for 11 weeks. Initial target concentrations were 0, 4, 25, and 200 mg/m³. However, because of excessive toxicity, the high-exposure level was reduced to 125 mg/m³ after 8 weeks. Exposed males were cohoused with two unexposed females immediately following the exposure period and later mated to an additional two unexposed females following a 16-week recovery period. Exposed females were cohoused with untreated males, and exposures were resumed after mating and continued during gestation. Some females were terminated at midgestation to assess fertility, while others were allowed to deliver their pups. F₁ animals were terminated for histological examination or mated to assess fertility. High-exposure level F₀ males were infertile after exposures, and there was little or no recovery. The fertility of low-exposure level males was not affected, but equivocal results were obtained at the mid-exposure level. In this study, testicular lesions were observed only in high level F₀ males. However, testicular lesions were also noted in a few males exposed to 4 and 25 mg/m³ in a concurrent subchronic toxicity study. Female fertility was apparently unaffected by exposure, and no treatment-related effects were noted in males or females exposed in utero.     

Peripheral cholinesterase inhibition by occupational chlorpyrifos exposure in Australian termiticide applicators.

Occupational exposure to organophosphorus insecticides (OPs), such as chlorpyrifos, may be monitored by the measurement of the activity of peripheral cholinesterase (ChE) enzymes, including erythrocyte acetylcholinesterase (EAChE) and serum cholinesterase (SChE). Lymphocyte neuropathy target esterase (NTE) is thought to have potential as a predictor of organophosphate-induced delayed neuropathy (OPIDN). This paper describes work performed in 39 Australian pest control operators (PCOs) exposed to a termiticide containing chlorpyrifos, and 34 unexposed control subjects. EAChE activities in PCOs did not differ from those of unexposed control workers. Mean NTE activity was slightly higher in PCOs than in controls and mean SChE was 52% of control activity. These results indicate that exposure of Australian PCOs to termiticides containing chlorpyrifos may be monitored using SChE but not EAChE or NTE, and that workers in this industry have sufficiently high OP exposure to significantly depress SChE activity. SChE inhibition of 70-80% may be associated with symptoms. Although no current symptoms were reported to be associated with occupational OP exposure, these workers may be at increased risk of acute effects following inadvertent spills or self-contamination due to their background level of exposure to OPs. While it is preferable to compare ChE enzyme activities between pre- and post-exposure periods to evaluate OP-related effects in individuals, in some cases there is an absence of pre-exposure data. The results of this study suggest that a screening value for SChE of 550 nmol/min/ml in a single blood sample may be useful to identify potentially OP-exposed individuals in the Australian population. Australian control subjects were similar with respect to EAChE, but displayed activities of NTE and SChE approximately 50 and 23% lower than an unexposed UK reference group. While these comparisons are presently speculative, they suggest that there may be differences in SChE and NTE activities in control populations of the two countries. The routine treatment of Australian homes with termiticides containing OPs, or differences in the availability and use of domestic OP-containing insecticides may explain these population differences. Further work is required to examine whether these differences are real, and if so their likely cause.     

Effect of methadone addiction on glucose metabolism in rats

Female albino rats were exposed to methadone over a 35-day period by addition of the drug in their drinking water. The final dose of the drug was 1.8 mg/kg body weight per day. After this period, the drug was withdrawn from some animals for 30 days (postexposure). Compared to unexposed controls, serum glucose levels rose during exposure and returned to control levels postexposure. Oral glucose tolerance tests showed impairment in 35-day drug-exposed animals compared to controls and postexposure. The activities of three key enzymes of glycolysis and three key enzymes of gluconeogenesis were measured in liver during and at the end of the exposure period, as well as postexposure. Compared to unexposed controls and postexposure, specific activities of two glycolytic enzymes in livers of exposed animals—hexokinase and phosphofructokinase 1—were significantly reduced, whereas the activity of a third glycolytic enzyme—pyruvate kinase—was unchanged. The specific activities of two gluconeogenic enzymes—glucose-6-phosphatase and fructose-1,6-biphosphatase—were significantly elevated in the drug-exposed animals compared to controls, whereas the activity of a third enzyme—phosphoenolpyruvate carboxykinase—was unchanged. These data indicate that methadone addiction produces a metabolic state similar to insulin-resistant diabetes.     

Reproduction in Fischer-344 Rats Exposed to Methyl Chloride by Inhalation For Two Generations

Reproduction in Fischer-344 Rats Exposed to Methyl Chlorideby Inhalation For Two Generations. HAMM, T. E., JR., RAYNOR,T. H., PHELPS, M. C, AUMAN, C. D., ADAMS, W. T., PROCTOR, J.E., AND WOLKOWSKI-TYL, R. (1985) Fund. Appl. Toxicol. 5, 568–577.Male and female Fischer-344 rats were exposed to methyl chlorideby inhalation (0, 150, 475, or 1500 ppm, 6 hr/day, 5 days/week,40 males and 80 females per group). The only treatment-relatedclinical signs were a 10 to 20% body weight gain depression(BWGD) in both males and females exposed to 1500 ppm at allweekly weighings after 2 weeks of exposure and a 5–7%BWGD in 475-ppm exposed animals after Day 57. After 10 weeksthe exposure schedule was changed to 6 hr/day, 7 days/week andeach male was mated to two exposed females. The mating periodwas ended after 2 weeks, at which point 10 males/group werenecropsied. The only tratment-related lesions Found were severebilateral testicular degeneration (10/10) and granulomas inthe epididymis (3/10) in the 1500-ppm males. The remaining 30males per group were then removed from exposure and mated duringa 2-week period with 60 unexposed females. The exposed femaleswere continued on exposure from the start of mating to PostnatalDay 28 (6 hr/day, 7 days/week). The females were not exposedfrom Gestation Day 18 to Postnatal Day 4, and the pups werenever directly exposed prior to weaning. There were no significantdifferences between groups in the number of exposed or unexposedfemales that mated, as evidenced by copulation plugs. No litterswere born to exposed or unexposed females mated to the 1500-ppmmales. There was no significant difference in the number oflitters produced by the 150-ppm groups when compared to thecontrol groups. Fewer litters were born in the 475-ppm groupsthan in the control groups. No differences in litter size, sexratio, pup viability, or pup growth were Found among the 475-ppm,150-ppm, or control F₀ groups. When bred 10 weeks after thecessation of exposures, 5 to 20 1500-ppm F₀ males had regainedthe ability to sire normal litters. The same number of 475-ppmF₀ males proved as fertile (15/ 20) as control F₀ males (13/20).After weaning, F₁ pups from the 475-, 150-, and 0-ppm groupswere exposed to the same concentrations of methyl chloride For10 weeks and then mated. A trend toward decreased fertilitywas Found in the 475-ppm F₁ group     

长期接触低浓度一氧化碳作业工人血中碳氧血红蛋白及血气分析

对８３例长期接触低浓度一氧化碳（ＣＯ）作业工人进行了血中碳氧血红蛋白（ＣＯＨｂ）含量的测定，血气分析及健康状况调查，并与６８名无毒害作业工人为对照做了对比分析。结果表明：①ＣＯ作业工人血中ＣＯＨｂ含量显著高于对照组，且就使血中ＣＯＨｂ升高而言，职业性接触ＣＯ显著高于吸烟，因此，ＣＯＨｂ是一个很好的接触指标；②ＣＯ作业工人末梢动脉血氧分压降低，并伴有神经衰弱和消化道障碍等症状。     

Behavioral responses of adult male and female fathead minnows to a model estrogenic effluent and its effects on exposure regime and reproductive success

Laboratory studies of adult male fathead minnows have shown that when they are exposed to estrogens, they lose their ability to compete for access to females and sire young, suggesting that estrogenic effluents may reduce the genetic fitness of populations of wild fishes. However, it is unknown whether wild fish which are exposed to effluent actually compete with unexposed fishes, how long effects of estrogen exposure last, and whether females are affected by estrogens. This study addressed these issues using the fathead minnow (FHM) and effluent from the Metropolitan Wastewater Treatment Plant (MWTP) a well-studied source of environmental estrogens (EEs) in the Mississippi River. Maze tests found that adult FHMs are neither attracted nor repelled by MWTP effluent while previous studies have shown that minnows are attracted to the warmer waters which characterize effluents; it is realistic that previously unexposed fish enter MWTP effluent in the spring and then compete with exposed individuals. Competitive spawning experiments showed that male FHMs exposed to 44ng E2/l (a high but realistic level) for three weeks failed to compete with unexposed males while males exposed to 4ng E2/l outcompeted and sired more young than unexposed males (p<0.05). The effects of estrogen exposure disappeared within a week of moving fish into uncontaminated water. Female FHM reproductive output and behavior were unaffected by exposure to estrogen. Taken together, these experiments suggest that the behavior of wild fishes likely determines their exposure to EEs and that while the effects of this exposure are likely significant to populations of wild fish, they will be location specific because of factors which determine the duration and intensity of male exposure. We conclude that the role of fish behavior in endocrine disruption strongly warrants additional consideration.     

Anesthetic gases and occupationally exposed workers

The aim of this study is to estimate whether the occupational exposure to low dose anesthetic gases could cause alterations of blood parameters in health care workers. 119 exposed subjects and 184 not exposed controls were included in the study. Each worker underwent the complete blood count test (CBC), proteinaemia, leukocyte count, serum lipids, liver and kidney blood markers.The liver blood markers show statistically significant differences in health care workers compared with controls (p < 0.05), a statistically significant decrease in neutrophils and an increase of lymphocytes in health care workers compared with controls (p < 0.05). The prevalence of values outside the range for GPT, GGT, total bilirubin, lymphocytes and neutrophils was statistically significant in health care workers compared with controls (p < 0.05). The results suggest that occupational exposure to low dose anesthetic gases could influence some haematochemical hepatic and hematopoietic parameters in exposed health care workers.     

In utero exposure to arsenite contributes to metabolic and reproductive dysfunction in male offspring of CD-1 mice

In utero exposure to arsenite (iAs) is known to increase disease risks later in life. We investigated the effect of in utero exposure to iAs in the drinking water on metabolic and reproductive parameters in male mouse offspring at postnatal and adult stages. Pregnant CD-1 mice were exposed to iAs (as sodium arsenite) in the drinking water at 0 (control), 10 ppb (EPA standard for drinking water), and 42.5 ppm (tumor-inducing dose in mice) from embryonic day (E) 10–18. At birth, pups were fostered to unexposed females. Male offspring exposed to 10 ppb in utero exhibited increase in body weight at birth when compared to controls. Male offspring exposed to 42.5 ppm in utero showed a tendency for increased body weight and a smaller anogenital distance. The body weight in iAs-exposed pups continued to increase significantly compared to control at 3 weeks and 11 weeks of age. At 5 months of age, iAs-exposed males exhibited greater body fat content and glucose intolerance. Male offspring exposed to 10 ppb in utero had higher circulating levels of leptin compared to control. In addition, males exposed to 42.5 ppm in utero exhibited decreased total number of pups born compared to controls and lower average number of litters sired over a six-month period. These results indicate that in utero exposure to iAs at either human relevant concentration or tumor-inducing concentration is a potential cause of developmental origin of metabolic and reproductive dysfunction in adult male mice.     

The relationship between occupational exposure to lead and manifestation of cardiovascular complications in persons with arterial hypertension

The chronic exposure to lead represents a risk factor of arterial hypertension development. Ambulatory blood pressure monitoring is the most prognostically reliable method of measuring of arterial blood pressure. The study is aimed at evaluating the relationship between occupational exposure to lead and manifestation of cardiovascular complications in patients with arterial hypertension. The studies included 73 men (mean age, 54.26 ± 8.17 years) with arterial hypertension, treated with hypotensive drugs: group I—persons occupationally exposed to lead (n = 35) and group II—individuals not exposed to lead (n = 38). An analysis of results obtained during ambulatory blood pressure monitoring disclosed significantly higher values of mean systolic blood pressure, mean blood pressure, pulse pressure, and variability of systolic blood pressure in the group of hypertensive patients occupationally exposed to lead as compared to patients with arterial hypertension but not exposed to lead. The logistic regression showed that a more advanced age, higher concentration of blood zinc protoporphyrin, and a higher mean value of pulse pressure represented independent risk factors of left ventricular hypertrophy in the group of persons with arterial hypertension and chronically exposed to lead (OR_age = 1.11; OR_ZnPP = 1.32; OR_PP = 1,43; p < 0.05). In view of the above data demonstration that occupational exposure to lead represents an independent risk factor of increased pulse pressure may be of key importance in the process of shaping general social awareness as to harmful effects of lead compounds on human health.     

Styrene-oxide N-terminal valine haemoglobin adducts in reinforced plastic workers: possible influence of genetic polymorphism of drug-metabolising enzymes

Styrene is one of the most important organic chemicals used worldwide. In humans, styrene metabolism involves oxidation by cytochrome P450 monooxygenases (CYPs) to styrene-7,8-oxide, an epoxide thought to be responsible for the genotoxic effects of styrene exposure, and detoxification by means of epoxide hydrolase (mEH) and glutathione S-transferases (GSTs). The objective of this study was to investigate if genetic polymorphisms of metabolic enzymes modulate the level of urinary styrene metabolites and styrene oxide adducts with N-terminal valine of human globin (SO-Hb) in 75 workers occupationally exposed to styrene and 77 unexposed controls. The mean air concentration of styrene in the breathing zone of workers (30.4ppm) was higher than the threshold limit value of 20ppm recommended by the American Conference of Governmental Industrial Hygienists (ACGIH), and the biological exposure index adopted by the ACGIH for exposure to styrene prior to the next shift (MA+PGA=400mg/g creatinine) was exceeded, indicating that styrene exposure for this group of workers was higher than recommended. A highly significant correlation was observed between styrene concentration in the breathing zone and the MA+PGA in urine of workers (r=0.85, P<0.001). The levels of SO-Hb adducts in exposed workers were significantly increased as compared with controls, although no difference was observed between subjects stratified as high and medium exposure categories based on MA+PGA excretion. Regarding the effect of the genetic polymorphisms we found that the level of SO-Hb adducts might be modulated by the predicted mEH enzymatic activity in the exposed workers. From our data we conclude that SO-Hb adduct measurement is a complementary method to MA+PG measurement for assessing exposure to styrene at occupational and environmental levels, which reflects a more extensive exposure period.     

Organophosphorus pesticide exposure decreases sperm quality: association between sperm parameters and urinary pesticide levels

Several studies have suggested that human semen quality has declined over the past decades and some of them have associated it with occupational exposure to pesticides. However, most of these studies have not been associated with a reliable exposure level and have been designed mostly as cross-sectional studies. The present work evaluates, in a longitudinal follow-up study, the effect of organophosphate pesticides (OP) at three occupational exposure levels on semen quality. In addition, the study examined the association between OP urinary levels and sperm parameters in exposed and unexposed workers. A total of 139 semen samples from 52 volunteers were assessed. Urinary OP levels were measured by gas-liquid chromatography.The results revealed that the poorest semen quality was found among the subjects with the highest OP exposure and the highest urinary OP levels. Seasonal variations in sperm concentration and sperm count were registered.The results showed a significant decrease in total sperm count among subjects with the highest exposure to OP. Further studies assessing the effects of OP on male reproductive health should be controlled by the variability in human sperm parameters, sperm seasonality, spermatogenesis time and the changing OP exposure level in men highly exposed to OP.