Monitoring and risk assessment of hazardous chemicals in toy-slime and putty in the Netherlands.

In 2019, the Dutch Food and Consumer Product Safety Authority performed a market surveillance for toy-slime (23 samples) and putty (16 samples). For 35% of the toy-slimes and 13% of the putties, the migration of boron exceeded the European legal limit of 300 and 1200 mg/kg respectively. In 36% of the toy samples, methylisothiazolinone (MI) and chloromethylisothiazolinone (CMI) were detected in levels up to 25 and 38 mg/kg, respectively, much higher than the European legal limit for aqueous toys intended for children younger than three.

Probabilistic derivation of the interspecies assessment factor for skin sensitization.

An interspecies sensitization assessment factor (SAF) is used in the quantitative risk assessment (QRA) for skin sensitization when a murine-based NESIL (No Expected Sensitization Induction Level) is taken as point of departure. Several studies showed that, on average, the murine sensitization threshold is in good correspondence with that determined in humans. However, on an individual level, the murine and human sensitization thresholds may differ considerably.

Aggregate exposure approaches for parabens in personal care products: a case assessment for children between 0 and 3 years old.

In the risk assessment of chemical substances, aggregation of exposure to a substance from different sources via different pathways is not common practice. Focusing the exposure assessment on a substance from a single source can lead to a significant underestimation of the risk. To gain more insight on how to perform an aggregate exposure assessment, we applied a deterministic (tier 1) and a person-oriented probabilistic approach (tier 2) for exposure to the four most common parabens through personal care products in children between 0 and 3 years old.

[Solvents for the removal of gutta-percha from root canals. 2. Side effects of chloroform, halothane and xylene].

High concentrations of organic solvents have adverse effects on the health of professional workers. In endodontics, halothane, chloroform and xylene are used to dissolve gutta-percha from root canals. It is therefore questioned whether the use of these solvents could affect the health of patients or of the dental team.

Potent inhibition of estrogen sulfotransferase by hydroxylated metabolites of polyhalogenated aromatic hydrocarbons reveals alternative mechanism for estrogenic activity of endocrine disrupters.

Polyhalogenated aromatic hydrocarbons (PHAHs), such as polychlorinated dibenzo-p-dioxins and dibenzofurans, polybrominated diphenylethers, and bisphenol A derivatives are persistent environmental pollutants, which are capable of interfering with reproductive and endocrine function in birds, fish, reptiles, and mammals. PHAHs exert estrogenic effects that may be mediated in part by their hydroxylated metabolites (PHAH-OHs), the mechanisms of which remain to be identified. PHAH-OHs show low affinity for the ER.

Potent inhibition of estrogen sulfotransferase by hydroxylated PCB metabolites: a novel pathway explaining the estrogenic activity of PCBs.

Polychlorinated biphenyls (PCBs) are persistent environmental pollutants which exert a variety of toxic effects in animals, including disturbances of sexual development and reproductive function. The estrogenic effects of PCBs may be mediated in part by hydroxylated PCB metabolites (PCB-OHs), but the mechanisms by which they are brought about are not understood. PCBs as well as PCB-Hs show low affinities for both alpha and beta estrogen receptor isoforms.

Effects of pentachlorophenol and hydroxylated polychlorinated biphenyls on thyroid hormone conjugation in a rat and a human hepatoma cell line.

It was previously demonstrated in our laboratory that hydroxylated metabolites of polychlorinated biphenyls (PCB-OHs) inhibit the sulfation of iodothyronines in rat liver cytosol. In this study, the inhibition of 3,3'-diiodothyronine (T2) sulfation by pentachlorophenol (PCP) and PCB-OHs was investigated in hepatoma cell lines in relation to the cellular uptake of these compounds, providing a more appropriate model of the in vivo situation. The human HepG2 hepatoma cell line was shown to conjugate T2 almost exclusively by sulfation, glucuronidation being negligible.

In vitro inhibition of thyroid hormone sulfation by polychlorobiphenylols: isozyme specificity and inhibition kinetics.

It was recently demonstrated by our laboratory that hydroxylated metabolites of polychlorinated biphenyls (PCB-OHs) are inhibitors of thyroid hormone sulfation. In this study, a more detailed investigation on sulfotransferase isozyme specificity and the kinetics of inhibition was performed. Thyroid hormone sulfation was determined using 3,3'-diiodothyronine (T2) as a substrate, and various sources of sulfotransferase (SULT) enzyme were used; e.

In vitro inhibition of thyroid hormone sulfation by hydroxylated metabolites of halogenated aromatic hydrocarbons.

Earlier studies in our laboratory showed that hydroxylated metabolites of polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) competitively inhibit thyroxine (T4) binding to transthyretin (TTR) and type I deiodinase (D1) activity. In this study, we investigated the possible inhibitory effects of hydroxylated metabolites of polyhalogenated aromatic hydrocarbons (PHAHs) on iodothyronine sulfotransferase activity. Rat liver cytosol was used as a source of sulfotransferase enzyme in an in vitro assay with 125I-labeled 3,3'-diiodothyronine (T2) as a model substrate.

Inhibition of thyroid hormone sulfation by hydroxylated metabolites of polychlorinated biphenyls.

In this study we investigated the possible inhibitory effects of hydroxylated metabolites of polychlorinated biphenyls (OH-PCBs) on iodothyronine sulfotransferase activity. The results indicate that OH-PCBs are potent inhibitors of this activity in vitro, with IC50 concentrations in the low micro molar range. Inhibition of sulfotransferase activity towards 3,3'-diiodothyronine (T2) was similar to that towards 3,3',5-triiodothyronine (T3) in this in vitro assay, therefore, T2 can be used as the model substrate for the active hormone T3.

Interactions of persistent environmental organohalogens with the thyroid hormone system: mechanisms and possible consequences for animal and human health.

Several classes of environmental contaminants have been claimed or suggested to possess endocrine-disrupting potency, which may result in reproductive problems and developmental disorders. In this paper the focus is on the multiple and interactive mechanisms of interference of persistent polyhalogenated aromatic hydrocarbons (PHAHs) and their metabolites with the thyroid hormone system. Evidence suggests that pure congeners or mixtures of PHAHs directly interfere with the thyroid gland; with thyroid hormone metabolizing enzymes, such as uridine-diphosphate-glucuronyl transferases (UGTs), iodothyronine deiodinases (IDs), and sulfotransferases (SULTs) in liver and brain; and with the plasma transport system of thyroid hormones in experimental animals and their offspring.

Modulating effects of thyroid state on the induction of biotransformation enzymes by 2,3,7,8-tetrachlorodibenzo-p-dioxin.

In this study we investigated to what extent the induction of detoxification enzymes by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is modulated by concomitant TCDD-induced changes in thyroid state. Euthyroid (Eu) male Sprague-Dawley rats, surgically thyroidectomized (Tx) rats and Tx rats receiving substitution doses of 3,3',5-triiodothyronine (Tx+T3) or thyroxine (Tx+T4) by osmotic minipumps were treated with a single ip injection of 10 μg TCDD/kg/bwt or with vehicle (corn oil). Three days after TCDD administration, rats were sacrificed and blood and livers were collected for analysis.

Extrathyroidal effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on thyroid hormone turnover in male Sprague-Dawley rats.

Treatment of rats with different polyhalogenated aromatic hydrocarbons strongly decreases plasma T4, with little or no decrease in plasma T3. The extrathyroidal effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on thyroid hormone turnover were studied by i.p.

Chemical suppression of feeding in larval weakfish (Cynoscion regalis) by trochophores of the serpulid polychaeteHydroides dianthus.

We studied the effect of exudates from trochophore larvae of the polychaeteHydroides dianthus on feeding in larval weakfish (Cynoscion regalis). Laboratory prey consisted ofH. dianthus trochophores and/or comparably sized rotifers (Brachionus plicatilis).