Detection of Styrene and Styrene Oxide‐Induced DNA Damage in Various Organs of Mice Using the Comet Assay

Styrene is an important high production volume chemical used to manufacture polymeric products. In 2018, International Agency for Research on Cancer classified styrene as probably carcinogenic to humans; National Toxicology Program lists styrene as reasonably anticipated to be a human carcinogen. The genotoxicity literature for styrene and its primary metabolite, styrene 7,8‐oxide (SO), begins in the 1970s. Organization of Economic Cooperation and Development (OECD) recently updated most genotoxicity test guidelines, making substantial new recommendations for assay conduct and data evaluation for the standard mutagenicity/clastogenicity assays. Thus, a critical review of the in vitro and in vivo rodent mutagenicity/clastogenicity studies for styrene and SO, based on the latest OECD recommendations, is timely. This critical review considered whether a study was optimally designed, conducted, and interpreted and provides a critical assessment of the evidence for the mutagenicity/clastogenicity of styrene/SO. Information on the ability of styrene/SO to induce other types of genotoxicity endpoints is summarized but not critically reviewed. We conclude that when styrene is metabolized to SO, it can form DNA adducts, and positive in vitro mutagenicity/clastogenicity results can be obtained. SO is mutagenic in bacteria and the in vitro mouse lymphoma gene mutation assay. No rodent in vivo mutation studies were identified. SO is clastogenic in cultured mammalian cells. Although the in vitro assays gave positive responses, styrene/SO is not clastogenic/aneugenic in vivo in rodents. In addition to providing updated information for styrene, this review demonstrates the application of the new OECD guidelines for chemicals with large genetic toxicology databases where published results may or may not be reliable. Environ. Mol. Mutagen. 2019. © 2019 Wiley Periodicals, Inc.

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“…We briefly describe two in vivo studies. Vaghef and Hellman () used a single i.p. injection of styrene or SO to expose female B57BL/6 mice.…”

Section: Critical Review Of the Individual Studies For Styrene/somentioning

confidence: 99%

Critical review of styrene genotoxicity focused on the mutagenicity/clastogenicity literature and using current organization of economic cooperation and development guidance

Moore¹,

Pottenger²,

House‐Knight³

2019

Environ and Mol Mutagen

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“…Thus, one of the conclusions would be that SO-induced DNA adducts in vivo is an indicator of the potential genotoxicity of styrene. Yet, results of the studies reported here using the most rigor- (Vaghef & Hellman, 1998) and in bone marrow/lymphocytes of mice exposed via inhalation (up to 21 days) to styrene (Vodicka et al, 2001), although these studies pre-dated the publication of internationally accepted protocols for their conduct.…”

Section: Discussionmentioning

confidence: 99%

“…Although there are several other in vivo studies that also reported negative results for MN induction following inhalation exposure to styrene or SO, the study by Gate et al is particularly relevant to the results of the current study given the similarity in the duration of exposure and adherence to the test guidelines. It should be mentioned that DNA strand breakage was reported in various organs of mice following intraperitoneal administration of styrene or SO (Vaghef & Hellman, 1998) and in bone marrow/lymphocytes of mice exposed via inhalation (up to 21 days) to styrene (Vodicka et al, 2001), although these studies pre‐dated the publication of internationally accepted protocols for their conduct.…”

Section: Discussionmentioning

confidence: 99%

Genotoxicity evaluation of orally administered styrene monomer in mice using comet, micronucleus, and Pig‐a endpoints

Gollapudi¹

2023

Environ and Mol Mutagen

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Male B6C3F1 mice were administered styrene monomer by oral gavage for 29 consecutive days at dose levels of 0, 75, 150, or 300 mg/kg/day. The highest dose level represented the maximum tolerated dose based on findings in a 28‐day dose range‐finding study, in which the bioavailability of orally administered styrene was also confirmed. The positive control group received ethyl nitrosourea (ENU; 51.7 mg/kg/day) on Study Days 1–3 and ethyl methanesulfonate (EMS; 150 mg/kg/day) on Study Days 27–29 by oral gavage. Approximately 3 h following the final dose, blood was collected to assess erythrocyte Pig‐a mutant and micronucleus frequencies. DNA strand breakage was assessed in glandular stomach, duodenum, kidney, liver, and lung tissues using the alkaline comet assay. The %tail DNA for stomach, liver, lung, and kidney in the comet assay among the styrene‐treated groups was neither significantly different from the respective vehicle controls nor was there any dose‐related increasing trend in any of the tissues; results for duodenum were interpreted to be inconclusive because of technical issues. The Pig‐a and micronucleus frequencies among styrene‐treated groups also did not show significant increases relative to the vehicle controls and there was also no evidence for a dose‐related increasing trend. Thus, orally administered styrene did not induce DNA damage, mutagenesis, or clastogenesis/aneugenesis in these Organization of Economic Co‐operation and Development test guideline‐compliant genotoxicity studies. Data from these studies can contribute to the overall assessment of genotoxic hazard and risk posed to humans potentially exposed to styrene.

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“…In addition, DNA adducts were found in several tissues such as the liver and lung in rodent studies [ 54 , 70 – 73 ]. Regarding other in vivo assays, the comet assay in the liver tissue of mouse showed positive results [ 74 , 75 ]. Our findings show that mutagenic effects were not observed in the lungs of mice that gavaged styrene at a carcinogenicity level [ 48 ] of 300 mg/kg/day.…”

Section: Discussionmentioning

confidence: 99%

In vivo mutagenicity assessment of styrene in MutaMouse liver and lung

Murata

Natsume²,

Iso

et al. 2023

Genes and Environ

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Background Styrene (CAS 100-42-5) is widely used as polystyrene and acrylonitrile–butadiene–styrene resin such as plastic, rubber, and paint. One of the primary uses of styrene is food utensils and containers, but a small amount of styrene transferred into food can be ingested by eating. Styrene is metabolized into styrene 7,8-oxide (SO). SO is mutagenic in bacteria and mouse lymphoma assays. It is clastogenic in cultured mammalian cells. However, styrene and SO are not clastogenic/aneugenic in rodents, and no rodent in vivo gene mutation studies were identified. Methods To investigate the mutagenicity of orally administered styrene, we used the transgenic rodent gene mutation assay to perform an in vivo mutagenicity test (OECD TG488). The transgenic MutaMouse was given styrene orally at doses of 0 (corn oil; negative control), 75, 150, and 300 mg/kg/day for 28 days, and mutant frequencies (MFs) were determined using the lacZ assay in the liver and lung (five male mice/group). Results There were no significant differences in the MFs of the liver and lung up to 300 mg/kg/day (close to maximum tolerable dose (MTD)), when one animal with extremely high MFs that were attributed to an incidental clonal mutation was omitted. Positive and negative controls produced the expected results. Conclusions These findings show that styrene is not mutagenic in the liver and lung of MutaMouse under this experimental condition.

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Detection of Styrene and Styrene Oxide‐Induced DNA Damage in Various Organs of Mice Using the Comet Assay

Cited by 27 publications

References 31 publications

Critical review of styrene genotoxicity focused on the mutagenicity/clastogenicity literature and using current organization of economic cooperation and development guidance

Critical review of styrene genotoxicity focused on the mutagenicity/clastogenicity literature and using current organization of economic cooperation and development guidance

Genotoxicity evaluation of orally administered styrene monomer in mice using comet, micronucleus, and Pig‐a endpoints

In vivo mutagenicity assessment of styrene in MutaMouse liver and lung

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