Francisco José Roma Paumgartten

Urinary, Circulating, and Tissue Biomonitoring Studies Indicate Widespread Exposure to Bisphenol A

Background Bisphenol A (BPA) is one of the highest-volume chemicals produced worldwide, and human exposure to BPA is thought to be ubiquitous. Thus, there are concerns that the amount of BPA to which humans are exposed may cause adverse health effects. Importantly, results from a large number of biomonitoring studies are at odds with the results from two toxicokinetic studies. Objective We examined several possibilities for why biomonitoring and toxicokinetic studies could come to seemingly conflicting conclusions. Data sources We examined > 80 published human biomonitoring studies that measured BPA concentrations in human tissues, urine, blood, and other fluids, along with two toxicokinetic studies of human BPA metabolism. Data extraction and synthesis The > 80 biomonitoring studies examined included measurements in thousands of individuals from several different countries, and these studies overwhelmingly detected BPA in individual adults, adolescents, and children. Unconjugated BPA was routinely detected in blood (in the nanograms per milliliter range), and conjugated BPA was routinely detected in the vast majority of urine samples (also in the nanograms per milliliter range). In stark contrast, toxicokinetic studies proposed that humans are not internally exposed to BPA. Some regulatory agencies have relied solely on these toxicokinetic models in their risk assessments. Conclusions Available data from biomonitoring studies clearly indicate that the general population is exposed to BPA and is at risk from internal exposure to unconjugated BPA. The two toxicokinetic studies that suggested human BPA exposure is negligible have significant deficiencies, are directly contradicted by hypothesis-driven studies, and are therefore not reliable for risk assessment purposes.

Mutagenicity testing of (±)-camphor, 1,8-cineole, citral, citronellal, (−)-menthol and terpineol with the Salmonella/microsome assay

The essential oils and their monoterpenoid constituents have been widely used as fragrances in cosmetics, as flavouring food additives, as scenting agents in a variety of household products, as active ingredients in some old drugs, and as intermediates in the synthesis of perfume chemicals. The present study was undertaken to investigate the mutagenic potential of six monoterpenoid compounds: two aldehydes (citral and citronellal), a ketone ((+/-)-camphor), an oxide (1,8-cineole, also known as eucalyptol), and two alcohols (terpineol and (-)-menthol). It is part of a more comprehensive toxicological screening of monoterpenes under way at our laboratory. Mutagenicity was evaluated by the Salmonella/microsome assay (TA97a, TA98, TA100 and TA102 tester strains), without and with addition of an extrinsic metabolic activation system (lyophilized rat liver S9 fraction induced by Aroclor 1254). In all cases, the upper limit of the dose interval tested was either the highest non-toxic dose or the lowest dose of the monoterpene toxic to TA100 strain in the preliminary toxicity test. No mutagenic effect was found with (+/-) camphor, citral, citronellal, 1,8-cineole, and (-) menthol. Terpineol caused a slight but dose-related increase in the number of his+ revertants with TA102 tester strain both without and with addition of S9 mixture. The results from this study therefore suggest that, with the exception of terpineol, the monoterpenoid compounds tested are not mutagenic in the Ames test.

Classification terms in developmental toxicology: need for harmonisation. Report of the Second Workshop on the Terminology in Developmental Toxicology Berlin, 27-28 August 1998.

Abstract The existence of ambiguities and inconsistencies in the use of terms for structural anomalies is a major problem in developmental toxicology and causes great difficulties for administrative decision makers involved in public health evaluation of chemical substances. The absence of harmonisation of terminology is no longer acceptable for regulatory purposes. The debate is unending, however, refinement and consensus are indispensable. This article is a report of the Second Workshop on Terminology in Developmental Toxicology. Experts from research institutions, regulatory agencies, and industries took part in this workshop, which has started a process of discussion that eventually will lead to a harmonisation of terminology used for classification of structural anomalies. The participants put forward a scheme of classification for foetal abnormalities that consists of only two categories: “malformation and variation.” Finally, consensus was achieved in defining the terms malformation and variation. Malformation is defined as a permanent structural change that is likely to adversely affect the survival or health of the species under investigation. The term variation is defined as a change that occurs within the normal population under investigation and is unlikely to adversely affect survival or health. This change might include a delay in growth or morphogenesis that has otherwise followed a normal pattern of development.

In vitro inhibition of CYP2B1 monooxygenase by β-myrcene and other monoterpenoid compounds

beta-myrcene (MYR) is an acyclic monoterpene found in the essential oils of several useful plants such as lemongrass (Cymbopogon citratus), hop, bay, verbena and others. Recently it has been reported that MYR as well as lemongrass oil blocked the metabolic activation of some promutagens (e.g., cyclophosphamide and aflatoxin B1) in in vitro genotoxicity assays. The present study was performed to evaluate the inhibitory effects of MYR and some other monoterpenoid compounds on microsomal enzymes involved in the activation of genotoxic substances. The effects of MYR and other monoterpenes on the activity of pentoxyresorufin-O-depenthylase (PROD), a selective marker for CYP2B1, was determined in a pool of liver microsomes prepared from phenobarbital-treated rats. The effect of MYR on the activity of ethoxyresorufin-O-deethylase (EROD), a marker for CYP4501A1, was investigated in liver microsomes of untreated rats. Results revealed that MYR had almost no effect on EROD (IC50 > 50 microM), but produced a concentration-dependent inhibition of PROD activity (IC50 =0.14 microM). The analysis of alterations produced by MYR on PROD kinetic parameters (Lineweaver-Burk plot) suggested that inhibition is competitive (Ki = 0.14 microM). The inhibitory effects of seven other monoterpenes on PROD activity (pentoxyresorufin 5 microM) were also studied and the IC50 were as follows: (-)-alpha-pinene, 0.087 microM; (+)-alpha-pinene, 0.089 microM; d-limonene, 0.19 microM; alpha-terpinene, 0.76 microM; citral, 1.19 microM; citronellal, 1.56 microM, and (+/-) camphor, 7.89 microM. The potent inhibitory effects on CYP4502B1 suggest that MYR, and other monoterpenes, interfere with the metabolism of xenobiotics which are substrates for this isoenzyme.

Biomonitoring studies should be used by regulatory agencies to assess human exposure levels and safety of bisphenol A.

Background Within the past 3 years, four major evaluations of bisphenol A (BPA) safety have been undertaken. However, these assessments have arrived at quite different conclusions regarding the safety of BPA at current human exposure levels. Objectives We compared the reasons provided by the European Food Safety Authority (EFSA) BPA risk assessment panel for their conclusion that human exposures are negligible with the conclusions reached by the other panels, with all panels having the same body of literature at their disposal. Discussion The EFSA panel dismissed ≥ 80 biomonitoring studies that documented significant levels of BPA exposure in humans, including internal exposures to unconjugated BPA, on the basis that they did not match a model of BPA metabolism. Instead, the EFSA panel relied on two toxicokinetic studies—conducted in 15 adults administered BPA—to draw conclusions about exposure levels in the population, including exposures of neonates. Conclusions As with all exposure assessments, models should be developed to explain actual data that are collected. In the case of BPA, samples from a large number of human subjects clearly indicate that humans are internally exposed to unconjugated BPA. The dismissal of these biomonitoring studies simply because their results do not conform to a model violates scientific principles. Expert panels should evaluate all data—including human biomonitoring studies—to make informed risk assessments.

Intoxicações e uso de pesticidas por agricultores do Município de Paty do Alferes, Rio de Janeiro, Brasil

This survey is part of a more comprehensive study on the health consequences of pesticide exposure. In the county (municipality) of Paty do Alferes, Rio de Janeiro State, Brazil, 55 agricultural workers were interviewed on the use of pesticides, use of personal protective equipment, data on health status, and symptoms related to pesticide exposure, disposal of agrochemical containers, and technical assistance. The most widely used pesticides were insecticides such as abamectin, organophosphate compounds, and pyrethroids, and fungicides such as mancozeb, chlorothalonil, and copper products. As a rule, pesticides are handled carelessly, and 92% of workers involved in the mixing, loading, and spraying of insecticides and fungicides used no protective clothing or equipment whatsoever. Some 62% of workers reported at least one illness associated with mixing or spraying pesticides. The most frequently reported symptoms were headache, nausea, vomiting, dizziness, skin irritation, and blurred vision, and 21% of affected workers required medical care. In more than half (51%) of the cases, workers reported using organophosphate insecticides from toxicological class I when they felt sick.

In vitro inhibition of liver monooxygenases by β-ionone, 1,8-cineole, (-)-menthol and terpineol

The present study was undertaken to investigate the inhibitory effects of beta-ionone, (-)-menthol, 1,8-cineole and alpha-terpineol on liver microsomal enzymes involved in the biotransformation of xenobiotic substances. The effects of beta-ionone and the foregoing monoterpenoid compounds on the activity of pentoxyresorufin-O-depentilase (PROD), a selective marker for CYP2B1, were determined in a pool of liver microsomes prepared from phenobarbital-treated rats. On the other hand, the inhibitory effects of these substances on the activities of ethoxyresorufin-O-deethylase (EROD), a marker for CYP1A1, and methoxyresorufin-O-demethylase (MROD), a marker for CYP1A2, were investigated in a pool of hepatic microsomes from beta-naphthoflavone-treated rats. Beta-ionone caused a concentration-related reduction of PROD activity with an IC50 value as low as 0.03 microM. The analysis of alterations produced by beta-ionone on PROD kinetic parameters (Lineweaver-Burk double-reciprocal plot) suggested that inhibition is non-competitive (Ki = 89.9 nM). Although being less potent than beta-ionone, 1,8-cineole (IC50 = 4.7 microM), (-)-menthol (IC50 = 10.6 microM) and terpineol (IC50 = 14.8 microM) also proved to be in vitro inhibitors of PROD reaction. Results also revealed that beta-ionone was a weak inhibitor of EROD (IC50 >100 microM) and MROD (IC50 >200 microM). Neither 1,8-cineole nor terpineol--tested in concentrations up to 150 microM--caused any decrease of EROD activity while (-)-menthol, at a concentration as high as 160 microM, produced only a slight reduction of the reaction rate. Terpineol (up to 150 microM) did not induce any reduction of MROD activity while 1,8-cineole (IC50 >300 microM) and (-)-menthol (IC50 >300 microM) caused only slight decreases of the reaction rate. The potent inhibitory effects on CYP2B1 suggest that beta-ionone, and the other monoterpenoids tested, may interfere with the metabolism of xenobiotics which are substrates for this isoenzyme.

Evaluation of the developmental toxicity of annatto in the rat

Annatto, a dye extracted from Bixa orellana seeds, is used as a color additive in butter, cheese and in a variety of other foods as well as in drugs and cosmetics. Toxicological data on annatto and on its main carotenoid pigment bixin are still scarce. In this study we evaluated the developmental toxicity of annatto (28% of bixin). Annatto (0, 31.2, 62.5, 125, 250 and 500 mg/kg body weight/day) was given by gavage to Wistar rats on days 6-15 of pregnancy. Ceasarean sections were performed on day 21. Implantations, living and dead fetuses and resorptions were recorded. Fetuses were weighed and examined for externally-visible anomalies. One-third of fetuses from each litter was examined for visceral anomalies by a microsectioning technique. The remaining fetuses were cleared and stained with Alizarin Red S for skeleton evaluation. No adverse effect of annatto on the mothers was noted. No increase in embryolethality and no reduction of fetal body weight were observed among annatto-exposed rats. Annatto did not induce any increase in the incidence of externally-visible, visceral or skeletal anomalies in the exposed offspring. These findings suggest that annatto was neither maternally toxic nor embryotoxic in the rat. Therefore, the no-observed-adverse-effect level (NOAEL) for annatto-induced maternal and developmental toxicity was 500 mg/kg body weight/day or greater (or > or = 140 mg bixin/kg body weight/day) by the oral route.

Chemical exposure during pregnancy and oral clefts in newborns

This article presents a literature review on the risk factors for oral clefts (lip and/or palate), emphasizing discussion of maternal exposure to endocrine disruptors. Several studies have identified the risk of cigarette smoking and alcohol consumption, use of anticonvulsant drugs, and exposure to organic solvents. A protective effect has been shown for supplementation with folic acid. As with other chemicals, the risk associated with exposure to sex hormones is still obscure, although some authors describe a moderate risk level. New studies addressing this hypothesis need to be conducted, while the population exposed to these endocrine disrupters is increasing.

Induction of liver monooxygenases by β-myrcene

Abstract β -Myrcene (MYR) is an acyclic monoterpene found in the essential oils of a variety of useful plants such as lemongrass ( Cymbopogon citratus ), hop, verbena, bay and others. MYR and essential oils containing this olefinic monoterpene are widely used as flavoring food additives, as fragrances in cosmetics and as scents in household products. The present study was undertaken to investigate the induction of liver monooxygenases by MYR. Female Wistar rats were treated by gavage with MYR (1000 mg/kg body weight) or corn oil (vehicle) for 1 or 3 consecutive days. Activities of ethoxycoumarin- O -deethylase (ECOD) and alkoxy-resorufin O -dealkylases (methoxy- (MROD), ethoxy- (EROD), pentoxy- (PROD) and benzyloxy-resorufin- O -dealkylation (BROD)) were determined fluorimetrically in the hepatic microsomal fraction. Exposure to MYR, either for 1 or 3 days, produced marked (13–34-fold) increases in the activities of PROD and BROD and only minor changes in ECOD, EROD and MROD. Since PROD and BROD are metabolized mainly by CYP2B isoenzymes, these results suggest that MYR induces this phenobarbital-inducible P450 subfamily. The induction of CYP2B isoenzymes was confirmed by SDS-PAGE and immunoblotting. Levels of apoproteins CYP2B1/2B2 were increased 8.2-fold after treatment with MYR (1000 mg/kg body wt, 3 days). Results from this study therefore indicate that MYR is an inducer of isoenzymes belonging to CYP2B subfamily.