Accumulation of carbon disulphide metabolites

Summary Biological monitoring for carbon disulphide (CS₂) exposure performed using the iodine-azide test (IAT) and 2-thiothiazolidine-4-carboxylic acid (TTCA) test in urinalysis of workers with high exposure to CS₂ (112–142 mg/m³, n = 34), workers with low exposure (4–7 mg/m³, n = 16), and non-exposed university workers (n =10). Pre-shift and post-shift urine specimens were collected on three consecutive days in the exposed and for only one day in the non-exposed. According to the findings the specificity and the sensitivity seem to be low for the IAT and high for the TTCA test. Contrary to a previous report all pre-shift urine samples showed negative IATs. The TTCA test was positive in pre-shift urine even after 32 to 63.5 h without exposure, and values tended to increase during consecutive days of exposure in highly exposed workers.The possible health implications of these findings should be further investigated.     

Determination of tetrahydrophtalimide and 2-thiothiazolidine-4-carboxylic acid,urinary metabolites of the fungicide captan,in rats and humans

Summary Capillary gas chromatographic (GC) methods using sulphur and mass selective detection for the qualitative and quantitative determination of tetrahydrophtalimide (THPI) and 2-thiothiazolidine-4-carboxylic acid (TTCA), urinary metabolites of the fungicide captan in rat and humans, were developed. Urinary detection limits were 2.7 g/l for THPI and 110 g/l for TTCA. Intraperitoneal and oral administration of captan to rats resulted in a 48-h cumulative urinary excretion of THPI of 1%–2% and 3%–9% of the dose, respectively. Cumulative urinary excretion of TTCA over 48 h ranged from 2% to 5% of the captan dose for the respective routes of administration. In urine of non-exposed human subjects, neither THPI nor TTCA could be detected. In urine of fruit-growers who were occupationally exposed to captan, both THPI and TTCA could be detected. Based on these results, THPI and TTCA are proposed as promising parameters for the biological monitoring of occupational exposure to captan.     

高效液相色谱法测定尿中2—硫代噻唑烷—4—羧酸浓度

本文报道了用高效液相色谱(HPLC)法测定尿中2-硫代噻唑烷-4_羧酸(TTCA),选用Spherisorbs ODS 2色谱柱。TTCA浓度在0～120ng范围内为直线相关,γ-0.999。本法回收率为72.9％,最低检出量4ng。30名不接触CS_2者尿样中有23名可检出TTCA占76.7％,与15名接触CS_2 10mg/m~3以下的工人尿中TTOA测得值比较,经两样本等级和检验有统计显著性。初步得出本法的特异度为97％、敏感度为73％。     

Toxicologic studies of N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide (captan): its metabolism by rat liver drug-metabolizing enzyme system

The degree of toxicity caused in rats by captan (N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide) administered intraperitoneally is greater than that induced by orally administered captan. With regard to its effect on the drug-metabolizing enzymes of rat liver, the activity of aniline hydroxylase and the level of cytochrome P-450 were found to decrease in the treated rats 24 h after a single oral dose (650 mg/kg). The loss was even greater in the animals receiving diethyl maleate 1 h prior to captan. Furthermore, usual increase in the activity of drug biotransformation enzymes seen after phenobarbital treatment appears to decrease in rats dosed with this funaicide. In vitro incubations of rat liver microsomes with captan resulted in a profound loss of cytochrome P-450 and the acitivty of benzphetamine N-demethylase as well as aniline hydroxylase. Although the inhibition of drug-metabolizing enzyme activity by captan was observed in microsomal incubations with or without NADPH, a detectable amount of carbonyl sulfide (COS) was found only in the incubations that contained captan plus NADPH. Carbonyl sulfide appears to arise from a captan-derived metabolite, thiophosgene (CSCl2), which decomposes to COS in aqueous solutions and in the presence of NADPH inhibits the activity of drug biotransformation enzymes.     

饮酒对尿2 -硫代噻唑烷-4-羧酸排泄的影响

目的观察饮酒对二硫化碳(CS2)接触者及非接触者尿2-硫代噻唑烷4羧酸(TTCA)排泄的影响。方法(1)男性非接触CS2志愿者10人,一次饮用38。白酒150ml或250ml,高效液相色谱法观察其尿TTCA排泄动态;(2)CS2作业男工152人,非接触者60人,分别收集班末尿和晨尿进行TTCA测定并进行问卷调查;同时进行个体空气采样和CS2浓度气相色谱法测定。结果非接触者一次饮白酒150ml后3h尿TTCA水平达峰值,12h后降至饮前水平(餐前0．5h,饮酒后1、3、12h中位数分别为0．045、0．068、0．099、0．046mg/gCr,n=10);TTCA水平随饮白酒剂量的增加而增高,饮0、150、250ml白酒者TTCA水平(中位数)分别为0．036、0．064、0．609mg/gCr(n=5,饮后3h)。CS2浓度为≤10．0、10．1～50．0、>50．0mg/m3时,CS2接触者TTCA有随CS2浓度增高而上升的趋势;对照组中饮白酒和啤酒者TTCA水平似高于不饮者,而接触组TTCA水平则随饮酒指数的增加而呈降低趋势。结论大量饮酒可影响尿TTCA水平,在进行CS2生物监测时,应避免在大量饮酒后12h内采集尿样,以避免饮酒对监测结果的干扰作用。     

TTCA measurements in biomonitoring of low-level exposure to carbon disulphide

Objectives: The biomonitoring of carbon disulphide exposure is currently performed by measuring the concentration of 2-thiothiazolidine-4-carboxylic acid (TTCA) in the urine of exposed workers. Methods: In this study the effect of TTCA, which is found in some vegetables, on the biomonitoring of low-level carbon disulphide exposure was evaluated. In addition the upper reference limit (URL) of TTCA in the non-exposed Finnish population was estimated by analysing TTCA in urine samples from 116 people. The samples were collected at health centres all over Finland from people in employment and in the age group 24–64 years. The analytical measurements were made using a modern column-switching technique and the results were compared with those from the same samples using the extraction method generally in use and, until now, recommended for the determination of TTCA in urine. Results: The results obtained with the two analytical methods correlated very well with each other (r=0.9). The liquid-liquid extraction method gave results constantly about 3.5 μmol/l higher than the column-switching method. The results of this study also confirmed that many cruciferous vegetables (Cruciferae) contain endogenous TTCA (0.6–5.0 mg/kg), which is excreted unchanged in the urine. After a normal meal which included these vegetables, the TTCA concentration did not rise above the biomonitoring action level even if this was as low as 2 mmol/mol creatinine, but was easily above the URL of TTCA in the non-exposed population. The URL, calculated as the 95th percentile, was 0.3 mmol/mol creatinine. Conclusion: The results showed that the extraction method was not sufficiently specific or sensitive when the TTCA concentrations were lower than 10 μmol/l. In contrast, the column-switching method seemed to give reliable results even at these low levels, which are the levels of interest in current practice. Received: 29 September 1999 / Accepted: 27 December 1999     

Effect of cytochrome P450 isozyme induction and glutathione depletion on the metabolism of CS2 to TTCA in rats

 Analysis of 2-thiothiazolidine-4-carboxylic acid (TTCA), a metabolite of carbon disulfide (CS₂), is used in the biological monitoring exposure to CS₂ at work. In order to clarify the metabolic reasons for individual variation in the urinary excretion of TTCA, the latter was studied in rats pretreated with model cytochrome P450 (CYP) enzyme inducers or glutathione (GSH) depletors. Ethanol, phenobarbital (PB) or 3-methylcholanthrene (MC) did not increase 24-h TTCA output following CS₂ inhalation (50 or 500 ppm, 6 h). After oral dosing (10 mg/rat), PB had an inhibiting effect on the excretion rate of TTCA. Tissue GSH depletors phorone, L-buthionine-(RS)-sulfoximine (BSO) and diethylmaleate (DEM) decreased TTCA excretion in rats given an oral dose (10 mg/rat) of CS₂. The initial inhibition by phorone and DEM was reversed after 6 h and from 12 h onward the TTCA in urine exceeded the control level, an effect not seen with BSO. The proportion of CS₂ excreted in urine as TTCA within 24 h was 1.7% in control rats and 1% after BSO treatment, 1.3% after PB, 1.7% after acetone, 1.8% after MC, 2.0% after phorone and 2.5% after DEM treatment. The amount of TTCA in urine increased with the CS₂ dose in a non-linear fashion: 1.6 μmol (50 ppm/6 h) vs. 4.9 μmol (500 ppm/6 h), and 0.2 μmol (1 mg/kg) versus 3.6 μmol (100 mg/kg). It is concluded that induction of different cytochrome P450 isoforms and transient glutathione depletion have only minor effects on the disposition of TTCA in rats following low-level CS₂ exposure persistently low glutathione level as achieved by E.G. BSO, markedly decreased the metabolism of CS₂ to TTCA; these metabolic effectors are unlikely to have a major role in the individual variation of CS₂ metabolism in exposed workers. Received: 14 June 1994/Accepted: 25 August 1994     

接触二硫化碳男工血清性激素水平及尿代谢物含量分析

为探讨长期接触二硫化碳（ＣＳ２）的粘胶纺丝男工血清性激素及尿２－硫代－噻唑啶－４－羧酸（ＴＴＣＡ）水平,应用放射免疫法测定接触工人血清性激素水平及用高效液相色谱法测定工人班末尿中ＴＴＣＡ含量。以多功能气体红外监测仪定点连续监测车间ＣＳ２浓度为（１４．４０±４．６２）ｍｇ／ｍ３（６．０１～２５．３０ｍｇ／ｍ３）,平均接触工龄为１０．４年。结果显示（１）接触组血清促卵泡激素〔ＦＳＨ：（１０．９４±７．３５）ＩＵ／Ｌ）〕明显高于对照组〔（７．５０±５．０７）ＩＵ／Ｌ〕;催乳素〔ＰＲＬ（５．７２±４．１８）ｎｇ／Ｌ〕则显著低于对照组〔（６．８９±４．６２）ｎｇ／Ｌ〕;血清促黄体激素（ＬＨ）、睾丸酮（Ｔ）等两组间均无统计学显著差异。但随着暴露工龄延长,ＨＬ含量明显下降。班的轮换不影响性激素水平。（２）在该接触浓度下工人班末尿ＴＴＣＡ为（１．０７２±１．０１３）ｍｇ／ｇ肌酐,随尿ＴＴＣＡ排出量增加,血清ＦＳＨ含量明显下降,存在接触－反应关系。本研究表明,现有接触水平对男工内分泌系统功能已造成一定损害。     

接触二硫化碳工人辨色错误得分水平及尿代谢物含量分析

目的为探讨长期接触CS2工人色觉功能及尿2-硫代塞唑烷-4-羧酸(TTCA)水平.方法应用FM100-HUE方法检测工人辨色能力,高效液相色谱测定工人班末尿中TTCA含量.结果CS2暴露组接触CS2时间加权平均浓度为15.53±6.29mg/m3.常规眼科检查未见特异损伤;FM100-HUE检查男、女工主要在5年～工龄段总错误得分水平、绿色及蓝色区带得分水平均显著高于同工龄段对照组(P＜0.05).暴露组女工尿TTCA含量低于男工(P＜0.01);15年工龄以上工人尿TTCA含量显著增高;10～15年工龄段男工尿TTCA含量与绿色区带的错误得分水平有一定相关性(P＜0.05).结论CS2对作业工人辨色力有一定影响,提示FM100-HUE辩色检查可作为低浓度CS2对视觉系统毒作用敏感的健康监测指标.     

尿中2-硫代噻唑烷-4-羧酸测定的反萃取高效液相色谱法

目的 建立尿中2-硫代噻唑烷-4-羧酸(TTCA)测定的反萃取高效液相色谱法.方法 取尿1 ml,分别加入2mol/L盐酸和水各0.5 ml,摇匀,加入4ml乙醚,振荡萃取2min后取出下层水相于具塞试管,用4ml乙醚再次萃取,合并2次萃取乙醚后取4ml,加入硼砂-磷酸二氢钾缓冲溶液2ml,振荡萃取2 min后取下层水相测定.采用C18色谱柱分离,紫外检测器检测,波长为273nm,流速为1.1ml/min,进样体积为20μl.结果 该方法的线性范围为1～10 μg,相关系数r=0.9995,最低检出浓度为0.1 μg/ml.尿中TTCA浓度为1、5、10 μg/ml时,日内精密度分别为:8.4％、3.0％和1.7％,日间精密度分别为11％、3.8％和1.9％;回收率为80％～ 102％.结论 本方法简便、快速、准确,适用于二硫化碳接触工人尿中TTCA含量的测定.