Induction of liver preneoplastic foci in F344 rats subjected to 28-day oral administration of diheptyl phthalate and its in vivo genotoxic potential

Biochemical and behavior effects induced by diheptyl phthalate (DHpP) and Diisodecyl phthalate (DIDP) exposed to zebrafish

Both Diheptyl-phthalate (DHpP) and Diisodecyl-phthalate (DIDP) were used extensively as plasticizers. Recently, their occurrence in the environmental matrices and human body fluids have been reported. Unfortunately, these phthalate congeners are without basic toxicity profiles. Hence, we studied the toxic effects of both DHpP and DIDP in the median lethal concentration (LC₅₀ 96-h) on zebrafish (Danio rerio). We assessed swimming behavior strength and tissues biomarker responses including total antioxidants capacity (TAOC), transaminases, and acetylcholinesterase (AChE) enzyme. Fish exposed to phthalate congeners (Treatment-I and-II) for 15-days showed alterations on fish swimming behavior and circadian rhythm. At the end of the exposure period, both liver and heart tissue transaminases activities were found to be accelerated in DHpP and DIDP treated fish, when compared to control group. TAOC and AChE activities were found to be decreased in brain, gills, intestine, and muscle tissues of phthalate congeners treated fish than the control group. Alterations observed in the studied biomarkers were concentration-based response. Among treatment groups DHpP showed higher effects. Comparative studies on swimming behavior and biochemical activities were reasonable to know the swimming responses are mediated due to external stress or internal stress. More studies on molecular and biomarkers assessments are warranted on toxicity of emerging contaminants.

Urinary Concentrations of Diisoheptyl Phthalate Biomarkers in Convenience Samples of U.S. Adults in 2000 and 2018-2019

We know little about the potential health risks from exposure to diisoheptyl phthalate (DiHpP), a plasticizer used in commercial applications. The production of DiHpP ended in the United States in 2010, but DiHpP may still be present in phthalate diester mixtures. To investigate human exposure to DiHpP, we used three oxidative metabolites of DiHpP: Monohydroxyheptyl phthalate (MHHpP), mono-oxoheptylphthalate (MOHpP), and monocarboxyhexyl phthalate (MCHxP) as exposure biomarkers. We analyzed urine collected anonymously in 2000 (N = 144) and 2018–2019 (N = 205) from convenience groups of U.S. adults using high-performance liquid chromatography coupled with isotope-dilution high-resolution mass spectrometry. We detected MCHxP in all the samples tested in 2000 (GM = 2.01 ng/mL) and 2018–2019 (GM = 1.31 ng/mL). MHHpP was also detected in 100% of the 2018–2019 samples (GM = 0.59 ng/mL) and 96% of the 2000 urine samples analyzed (GM = 0.38 ng/mL). MOHpP was detected in 57% (2018–2019, GM = 0.03 ng/mL) and 92% (2000, GM = 0.19 ng/mL) of samples. The presence of MHHpP, MOHpP, and MCHxP in the 2018–2019 samples suggests recent exposure to DiHpP. Intercorrelations between metabolite concentrations were more significant in samples collected in 2000 than in samples collected in 2018–2019. The differences in urinary metabolite profiles and intercorrelations from samples collected during 2000 and 2018–2019 likely reflects changes in the composition of commercial DiHpP formulations before and after 2010.

Presence of phthalate esters in intravenous solution evaluated using gas chromatography-mass spectrometry method

Di-(2-ethylhexyl) phthalate (DEHP) is a plasticizer widely used in the production of poly-(vinyl) chloride (PVC) materials. It is a reproductive and developmental toxicant in animals and a suspected endocrine modulator in humans. DEHP is not covalently bound within the PVC molecule, which is why migration into a suitable medium can be expected. Since application of infusion solutions is one of the most common medical treatments, the objective of this study was to determine the migration of phthalates from softened PVC storage bags into infusion solution in different time periods within one year from date of production using a gas chromatography-mass spectrometry method. The measured values of DEHP ranged between 0.22 and 14.00 µg l(-1) , but the unexpected presence of other phthalate esters was also detected. It was concluded that values obtained in infusion solutions match the reference data and represent a minor risk for the patient. The presence of other phthalate esters leads to the conclusion that the pharmacopeic requirement for polymer cleanness was not fully met. Since phthalate esters are among the most extensively used industrial chemicals and are widely distributed in the environment, special precautions and further monitoring should be conducted to minimize any possible health risks.

A core in vitro genotoxicity battery comprising the Ames test plus the in vitro micronucleus test is sufficient to detect rodent carcinogens and in vivo genotoxins

In vitro genotoxicity testing needs to include tests in both bacterial and mammalian cells, and be able to detect gene mutations, chromosomal damage and aneuploidy. This may be achieved by a combination of the Ames test (detects gene mutations) and the in vitro micronucleus test (MNvit), since the latter detects both chromosomal aberrations and aneuploidy. In this paper we therefore present an analysis of an existing database of rodent carcinogens and a new database of in vivo genotoxins in terms of the in vitro genotoxicity tests needed to detect their in vivo activity. Published in vitro data from at least one test system (most were from the Ames test) were available for 557 carcinogens and 405 in vivo genotoxins. Because there are fewer publications on the MNvit than for other mammalian cell tests, and because the concordance between the MNvit and the in vitro chromosomal aberration (CAvit) test is so high for clastogenic activity, positive results in the CAvit test were taken as indicative of a positive result in the MNvit where there were no, or only inadequate data for the latter. Also, because Hprt and Tk loci both detect gene-mutation activity, a positive Hprt test was taken as indicative of a mouse-lymphoma Tk assay (MLA)-positive, where there were no data for the latter. Almost all of the 962 rodent carcinogens and in vivo genotoxins were detected by an in vitro battery comprising Ames+MNvit. An additional 11 carcinogens and six in vivo genotoxins would apparently be detected by the MLA, but many of these had not been tested in the MNvit or CAvit tests. Only four chemicals emerge as potentially being more readily detected in MLA than in Ames+MNvit--benzyl acetate, toluene, morphine and thiabendazole--and none of these are convincing cases to argue for the inclusion of the MLA in addition to Ames+MNvit. Thus, there is no convincing evidence that any genotoxic rodent carcinogens or in vivo genotoxins would remain undetected in an in vitro test battery consisting of Ames+MNvit.

Evaluation of in vivo genotoxic potential of fenofibrate in rats subjected to two-week repeated oral administration

Fenofibrate (FF), a peroxisome proliferator-activated receptor-alpha agonist, has been used as one of the hypolipidemic drugs in man and induces oxidative stress and promotes hepatocarcinogenesis in the liver of rodents. This chemical belongs to a class of non-genotoxic carcinogens, but DNA damage secondary to oxidative stress resulting from reactive oxygen species (ROS) generation is suspected in rodents given this chemical. To examine whether FF has genotoxic potential, partially hepatectomized F344 male rats were treated orally with 0, 1,000 or 2,000 mg/kg of FF for 2 weeks, followed by diet containing 0.15% 2 acetyl aminofluorene (2 AAF) for enhancement the tumor-promoting effect for 10 days and a single oral dose of carbon tetrachloride (CCl4) as the first experiment (liver initiation assay). As the second experiment, the in vivo liver comet assay was performed in hepatectomized rats, and the expression of some DNA repair genes was examined. In the liver initiation assay, the number and area of glutathione S-transferase placental form (GST-P)-positive single cells and foci did not increase in the FF treated groups. In the comet assay, positive results were obtained after 3 h of the last treatment of FF, and the expression of some DNA repair genes such as Apex1, Ogg1 and Mlh1 were upregulated in rats given the high dose of FF at 3 h after the treatment but not in 24 h after the treatment. The results of the present study suggest that FF causes some DNA damage in livers of rats, but is not a strong genotoxic substance leading to a DNA mutation since such DNA damage was repaired by the increased activity of some DNA repair genes.