Evaluation of potential health effects associated with occupational and environmental exposure to styrene - an update.

The potential chronic health risks of occupational and environmental exposure to styrene were evaluated to update health hazard and exposure information developed since the Harvard Center for Risk Analysis risk assessment for styrene was performed in 2002. The updated hazard assessment of styrene's health effects indicates human cancers and ototoxicity remain potential concerns. However, mechanistic research on mouse lung tumors demonstrates these tumors are mouse-specific and of low relevance to human cancer risk. The updated toxicity database supports toxicity reference levels of 20 ppm (equates to 400 mg urinary metabolites mandelic acid + phenylglyoxylic acid/g creatinine) for worker inhalation exposure and 3.7 ppm and 2.5 mg/kg bw/day, respectively, for general population inhalation and oral exposure. No cancer risk value estimates are proposed given the established lack of relevance of mouse lung tumors and inconsistent epidemiology evidence. The updated exposure assessment supports inhalation and ingestion routes as important. The updated risk assessment found estimated risks within acceptable ranges for all age groups of the general population and workers with occupational exposures in non-fiber-reinforced polymer composites industries and fiber-reinforced polymer composites (FRP) workers using closed-mold operations or open-mold operations with respiratory protection. Only FRP workers using open-mold operations not using respiratory protection have risk exceedances for styrene and should be considered for risk management measures. In addition, given the reported interaction of styrene exposure with noise, noise reduction to sustain levels below 85 dB(A) needs be in place.

The excretion of 2-hydroxyestrone during the menstrual cycle.

A double isotope derivative determination technique was developed to investigate the excretion of 2-hydroxyestrone inhuman menstrual cycle. The method is highly specific, accurate and precise within the range of 0.2-20 nmol 2-hydroxyestrone/20ml of urine. The amounts of 2-hydroxyestrone excreted during menstrual cycle varied between 10 (proliferation phase) and 60 mug/24 h urine (ovulatory peak), which is comparable to that of estriol, supposed hitherto to be the main excretion product of estrogen metabolism.

Excretion of 2-hydroxyestrone in urine throughout human pregnancies.

Urinary 2-hydroxyesterone was quantitatively determined in the course of several normal human pregnancies. The urine was subjected to hot acid hydrolysis and after chromatographic purification, 2-hydroxyesterone was converted into the corresponding phenazine derivative, which was submitted to a final column chromatogrphy and then quantitated by UV-spectrometry. For correction of procedural losses 2-hydroxyestrone-4-14C was used as internal standard. The urinary 2-hydroxyestrone of different subjects varied within a wide range especially at mid-pregnancy between 100 and 2500 mug/24 h. The day-to-day variation of the excretion of 2-hydroxyestrone was mostly less than 30% of the total value of that day, but sometimes could even reach 60%. The investigation of 2-hydroxyestrone and total estrogens at regular intervals throughout several pregnancies, showed that the excretion of 2-hydroxyesterone generally reached a maximum during the second trimester, while the excretion of the total estrogens steadily increased up to parturition. When analyzing the urines of different subjects during the last 4 months of pregnancy, no correlation appeared to exist for the excretions of the total estrogens and of 2-hydroxyestrone.

Changes in the classification of carcinogenic chemicals in the work area. (Section III of the German List of MAK and BAT values).

Carcinogenic chemicals in the work area were previously classified into three categories in section III of the German List of MAK and BAT values (the list of values on maximum workplace concentrations and biological tolerance for occupational exposures). This classification was based on qualitative criteria and reflected essentially the weight of evidence available for judging the carcinogenic potential of the chemicals. In the new classification scheme the former sections IIIA1, IIIA2, and IIIB are retained as categories 1, 2, and 3, to correspond with European Union regulations. On the basis of our advancing knowledge of reaction mechanisms and the potency of carcinogens, these three categories are supplemented with two additional categories. The essential feature of substances classified in the new categories is that exposure to these chemicals does not contribute significantly to the risk of cancer to man, provided that an appropriate exposure limit (MAK value) is observed. Chemicals known to act typically by non-genotoxic mechanisms, and for which information is available that allows evaluation of the effects of low-dose exposures, are classified in category 4. Genotoxic chemicals for which low carcinogenic potency can be expected on the basis of dose/response relationships and toxicokinetics and for which risk at low doses can be assessed are classified in category 5. The basis for a better differentiation of carcinogens is discussed, the new categories are defined, and possible criteria for classification are described. Examples for category 4 (1,4-dioxane) and category 5 (styrene) are presented.

OECD test strategies and methods for endocrine disruptors.

The question whether (man-made or natural) chemical substances may have an adverse effect on the endocrine system has gained high visibility in the public as well as in the scientific community. This relates to possible effects on the environment as well as on human health for chemicals with (anti)estrogenic, (anti)androgenic or (anti)thyroid activity. Taking into account the broad universe of chemicals to which humans or the environment may be exposed, a sound testing strategy and robust test methods are urgently needed. Both subjects have been addressed by a specific OECD working group (EDTA-Endocrine Disruptor Testing and Assessment Task Force) involving regulatory agencies, the scientific community, chemical industry and NGOs. Like other organizations the OECD has adopted a tiered-testing strategy with the first tier using screening assays as quick and inexpensive tools, providing a way of generating alerts to potential endocrine activity that can be used to prioritize substances for definitive tests that then can determine the toxicological consequences of endocrine toxicity. The efforts of the OECD have therefore concentrated on the validation of specific screening and testing guidelines, like the uterotrophic, the Hershberger, and the "enhanced TG 407" test. The experimental testing necessary for this validation procedure is completed for the uterotrophic and the "enhanced TG 407" tests and near completion for the Hershberger assay. The data obtained so far have been published (for the uterotrophic assay) or will be submitted to the EDTA working group for final evaluation. Overall, the validation program has been very successful and should be sufficient for setting up OECD test guidelines for these experimental procedures. This will add substantially to the "tool-box" of OECD test methods that is available internationally to regulatory agencies and chemical industry for the identification and assessment of possible endocrine disruptors. Despite this success it is well recognized that the methodological "tool-box" should be supplemented by further screening and testing procedures related to effects on human health and the environment.

In vitro cytotoxicity of glycol ethers and oxidation products in CHO cells.

The cytotoxicity of several glycol ethers and of some of their oxidation products, the corresponding alkoxy acetates, was compared in Chinese hamster ovary (CHO-K1) cells without metabolic activation. Cytotoxicity was measured in terms of cloning formation ability, and EC50 values (concentrations allowing 50% of the seeded cells to form colonies) were estimated. The results, in the case of unmetabolized glycol ethers tested, showed an increase in toxicity with increasing chain length. The cytotoxicity of the corresponding alkoxy acetates, however, did not exhibit a trend in parallel with the chemical structure. 2-Methoxypropionic acid was somewhat less cytotoxic than the alkoxy acetic acids investigated. It is concluded that gross cytotoxicity to dividing cells is not the predominant mechanism for the teratogenicity or myelotoxicity and testes toxicity of methoxy- and ethoxyethanol, which produce these effects after oxidation to their corresponding alkoxy acetates.

Formation of thermally stable derivatives of chlordiazepoxide and its desmethyl metabolite for GLC.

A derivatization procedure is described for the GLC determination of subnanogram amounts of chlordiazepoxide and nanogram amounts of N-desmethylchlordiazepoxide. Treatment with acetic anhydride at elevated temperature eliminates the highly polar and unstable nitrone group of these compounds by rearrangement and acetylation. The mass spectrometric fragmentation pattern of the acetyl derivatives is recorded and interpreted.

Assessment of structurally related chemicals: toxicity and ecotoxicity of acrylic acid and acrylic acid alkyl esters (acrylates), methacrylic acid and methacrylic acid alkyl esters (methacrylates).

BUA compiled the available data on toxicity and ecotoxicity for several acrylic and methacrylic acid esters and their corresponding acids. A comparison of these data revealed a qualitative similarity in the toxicological and ecotoxicological properties of the compounds considered. The data indicate that methacrylates are less reactive than the corresponding acrylates.

Evaluation of historical control data in carcinogenicity studies.

Results obtained in long-term carcinogenicity studies with animals should be evaluated, first and foremost, by statistical comparisons of the data obtained from the treated group with that from the concurrent control group. Often the results are compared with data from so-called historical control groups in order to take variations in the incidences of spontaneous tumours into account. Because historical control data change in the course of time and for a variety of reasons, certain requirements must be met before they may be used in the evaluation of the results of long-term studies. The present paper discusses potential sources of variability of tumour incidences in untreated animals, presents databanks for historical control data, mentions the factors that affect tumour incidences in untreated animals and describes biostatistical data evaluation. Finally, details are given of the criteria used by the DFG Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area to decide whether historical control data may be applied. These include the requirement that the historical control data were obtained with animals of the same species and strain and from the same breeder. The data were obtained in the same laboratory, the study design, experimental methods and assessment criteria were the same, and the studies used for the comparison were carried out within a limited time window. Historical control data that have not been published may be used provided they fulfil the above criteria and have been made available in sufficient detail to be comprehensible.

[Determination of morphine in the vitreous and cerebrospinal fluid by radioimmunoassay (author's transl)]. / Radioimmunologische Morphinbestimmung in der Glaskörperflüssigkeit des Auges und im Liquor cerebrospinalis

In 12 cases of fatal poisoning with morphine or heroin a radioimmunological determination of morphine was carried out in vitreous humor, cerebrospinal fluid and urine. The concentrations varied between 30 and 350 ng of morphine-equivalents/ml in the cerebrospinal fluid and between 45 and 280 ng/ml in the vitreous humor (urine concentrations: 120-100.000 ng/ml). The counts per minute differed significantly for samples with and without prior ingestion of morphine, when vitreous and cerebrospinal fluids were tested by the morphine (3H) radioimmunoassay. Thereby it was clearly demonstrated, that radioimmunoassay is a valuable screening procedure for the rapid identification of morphine in corpses, even when urine is not available.

Suicide by an overdosage of N-propylajmalinium bitartrate.

The toxicological findings after suicidal poisoning with N-propylajmalinium bitartrate (NPAB) are presented. For isolation of NPAB the biological material was homogenized and the drug was isolated by adsorption on Amberlite XAD-2. After column chromatographic purification on Sephadex LH-20 quantitative determinations were carried out by gas chromatography of the trifluoroacetate. The identity of the material finally obtained was checked by various chromatographic and spectrometric methods. The following concentrations of NPAB were found: liver 58 microgram/g, kidney 32 microgram/g, brain 16 microgram/g, muscle less than 10 microgram/g, heart less than 5 microgram/g, blood less than 5 microgram/g, gastric contents 600 mg (total). 1200 mg of NPAB had been swallowed; thus the amount of NPAB, that had crossed into blood, was approx. 500-600 mg corresponding to a dose of 9-11 mg/kg body weight.

A micromethod for the isolation of drugs from blood using amberlite XAD-2.

The extraction of drugs from small blood samples (1 ml or less) for subsequent quantitative determination is described. Isolation was carried out by adsorption of the drugs to Amberlite XAD-2 resin utilizing a batch procedure that enabled the simultaneous extraction of up to 200 samples in approx. 5 hours. A new desorption technique yielded extracts of high purity that could be used directly for gas chromatographic or radioimmunological determinations, even if hemolyzed or putrid blood was to be examined. The following 26 substances were quantitated after addition to postmortem blood speciments at concentrations of 1-10 microgram/ml: tilidine, diphenhydramine, dibenzepine, imipramine, chlorpromazine, amphetamine, pentazocine, phenacetin, methaqualone, meprobamate, parathion, diazepam, digoxin, beta-methyldigoxin, carbromal, glutethimide, amobarbital, pentobarbital, cyclobarbital, phenobarbital, diphenylhydantoin, carbutamide, tolbutamide, glycodiazin, tolazamide and chlorpropamide. Thereby recoveries of 60-100% could be achieved. The reproducibility of the procedure was satisfactory as demonstrated by coefficients of variation of 3.7-8%.