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Frank EA, Meek MEB. Procedural application of mode-of-action and human relevance analysis: styrene-induced lung tumors in mice. Crit Rev Toxicol 2024; 54:134-151. [PMID: 38440945 DOI: 10.1080/10408444.2024.2310600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 01/18/2024] [Indexed: 03/06/2024]
Abstract
Risk assessment of human health hazards has traditionally relied on experiments that use animal models. Although exposure studies in rats and mice are a major basis for determining risk in many cases, observations made in animals do not always reflect health hazards in humans due to differences in biology. In this critical review, we use the mode-of-action (MOA) human relevance framework to assess the likelihood that bronchiolar lung tumors observed in mice chronically exposed to styrene represent a plausible tumor risk in humans. Using available datasets, we analyze the weight-of-evidence 1) that styrene-induced tumors in mice occur through a MOA based on metabolism of styrene by Cyp2F2; and 2) whether the hypothesized key event relationships are likely to occur in humans. This assessment describes how the five modified Hill causality considerations support that a Cyp2F2-dependent MOA causing lung tumors is active in mice, but only results in tumorigenicity in susceptible strains. Comparison of the key event relationships assessed in the mouse was compared to an analogous MOA hypothesis staged in the human lung. While some biological concordance was recognized between key events in mice and humans, the MOA as hypothesized in the mouse appears unlikely in humans due to quantitative differences in the metabolic capacity of the airways and qualitative uncertainties in the toxicological and prognostic concordance of pre-neoplastic and neoplastic lesions arising in either species. This analysis serves as a rigorous demonstration of the framework's utility in increasing transparency and consistency in evidence-based assessment of MOA hypotheses in toxicological models and determining relevance to human health.
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Affiliation(s)
- Evan A Frank
- National Institute for Occupational Safety and Health, Cincinnati, OH, USA
| | - M E Bette Meek
- School of Epidemiology and Public Health in the Faculty of Medicine, University of Ottawa, Ottawa, Canada
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2
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Borgert CJ. Hypothesis-driven weight of evidence evaluation indicates styrene lacks endocrine disruption potential. Crit Rev Toxicol 2023:1-16. [PMID: 37216681 DOI: 10.1080/10408444.2022.2112652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 08/01/2022] [Accepted: 08/02/2022] [Indexed: 05/24/2023]
Abstract
Styrene is among the U.S. EPA's List 2 chemicals for Tier 1 endocrine screening subject to the agency's two-tiered Endocrine Disruptor Screening Program (EDSP). Both U.S. EPA and OECD guidelines require a Weight of Evidence (WoE) to evaluate a chemical's potential for disrupting the endocrine system. Styrene was evaluated for its potential to disrupt estrogen, androgen, thyroid, and steroidogenic (EATS) pathways using a rigorous WoE methodology that included problem formulation, systematic literature search and selection, data quality evaluation, relevance weighting of endpoint data, and application of specific interpretive criteria. Sufficient data were available to assess the endocrine disruptive potential of styrene based on endpoints that would respond to EATS modes of action in some Tier 1-type and many Tier 2-type reproductive, developmental, and repeat dose toxicity studies. Responses to styrene were inconsistent with patterns of responses expected for chemicals and hormones known to operate via EATS MoAs, and thus, styrene cannot be deemed an endocrine disruptor, a potential endocrine disruptor, or to exhibit endocrine disruptive properties. Because Tier 1 EDSP screening results would trigger Tier 2 studies, like those evaluated here, subjecting styrene to further endocrine screening would produce no additional useful information and would be unjustified from animal welfare perspectives.
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Affiliation(s)
- Christopher J Borgert
- Applied Pharmacology and Toxicology Inc, Gainesville, FL, USA
- Department of Physiological Sciences, University of Florida College of Veterinary Medicine, Gainesville, FL, USA
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Murata Y, Natsume M, Iso T, Shigeta Y, Hirose N, Umano T, Horibata K, Sugiyama KI, Masumura K, Hirose A, Matsumoto M. In vivo mutagenicity assessment of styrene in MutaMouse liver and lung. Genes Environ 2023; 45:12. [PMID: 37041654 PMCID: PMC10088199 DOI: 10.1186/s41021-023-00270-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 03/16/2023] [Indexed: 04/13/2023] Open
Abstract
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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Affiliation(s)
- Yasumasa Murata
- Division of Risk Assessment, National Institute of Health Sciences, Kanagawa, Japan
| | - Masakatsu Natsume
- Genotoxicology Laboratory, BioSafety Research Center Inc, Shizuoka, Japan
| | - Takako Iso
- Division of Risk Assessment, National Institute of Health Sciences, Kanagawa, Japan
| | - Yoshiyuki Shigeta
- Division of Risk Assessment, National Institute of Health Sciences, Kanagawa, Japan
| | - Nozomu Hirose
- Division of Risk Assessment, National Institute of Health Sciences, Kanagawa, Japan
| | - Takaaki Umano
- Division of Risk Assessment, National Institute of Health Sciences, Kanagawa, Japan
| | - Katsuyoshi Horibata
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, Kanagawa, Japan
| | - Kei-Ichi Sugiyama
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, Kanagawa, Japan
| | - Kenichi Masumura
- Division of Risk Assessment, National Institute of Health Sciences, Kanagawa, Japan
| | - Akihiko Hirose
- Division of Risk Assessment, National Institute of Health Sciences, Kanagawa, Japan
- Chemicals Evaluation and Research Institute, Tokyo, Japan
| | - Mariko Matsumoto
- Division of Risk Assessment, National Institute of Health Sciences, Kanagawa, Japan.
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Api AM, Belsito D, Botelho D, Bruze M, Burton GA, Cancellieri MA, Chon H, Dagli ML, Date M, Dekant W, Deodhar C, Fryer AD, Jones L, Joshi K, Kumar M, Lapczynski A, Lavelle M, Lee I, Liebler DC, Moustakas H, Na M, Penning TM, Ritacco G, Romine J, Sadekar N, Schultz TW, Selechnik D, Siddiqi F, Sipes IG, Sullivan G, Thakkar Y, Tokura Y. RIFM fragrance ingredient safety assessment, styrene, CAS Registry Number 100-42-5. Food Chem Toxicol 2022; 165 Suppl 1:113138. [PMID: 35595040 DOI: 10.1016/j.fct.2022.113138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 05/06/2022] [Accepted: 05/12/2022] [Indexed: 11/18/2022]
Affiliation(s)
- A M Api
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - D Belsito
- Member Expert Panel for Fragrance Safety, Columbia University Medical Center, Department of Dermatology, 161 Fort Washington Ave., New York, NY, 10032, USA
| | - D Botelho
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - M Bruze
- Member Expert Panel for Fragrance Safety, Malmo University Hospital, Department of Occupational & Environmental Dermatology, Sodra Forstadsgatan 101, Entrance 47, Malmo, SE-20502, Sweden
| | - G A Burton
- Member Expert Panel for Fragrance Safety, School of Natural Resources & Environment, University of Michigan, Dana Building G110, 440 Church St., Ann Arbor, MI, 58109, USA
| | - M A Cancellieri
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - H Chon
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - M L Dagli
- Member Expert Panel for Fragrance Safety, University of Sao Paulo, School of Veterinary Medicine and Animal Science, Department of Pathology, Av. Prof. dr. Orlando Marques de Paiva, 87, Sao Paulo, CEP 05508-900, Brazil
| | - M Date
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - W Dekant
- Member Expert Panel for Fragrance Safety, University of Wuerzburg, Department of Toxicology, Versbacher Str. 9, 97078, Würzburg, Germany
| | - C Deodhar
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - A D Fryer
- Member Expert Panel for Fragrance Safety, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR, 97239, USA
| | - L Jones
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - K Joshi
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - M Kumar
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - A Lapczynski
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - M Lavelle
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - I Lee
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - D C Liebler
- Member Expert Panel for Fragrance Safety, Vanderbilt University School of Medicine, Department of Biochemistry, Center in Molecular Toxicology, 638 Robinson Research Building, 2200 Pierce Avenue, Nashville, TN, 37232-0146, USA
| | - H Moustakas
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - M Na
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - T M Penning
- Member of Expert Panel for Fragrance Safety, University of Pennsylvania, Perelman School of Medicine, Center of Excellence in Environmental Toxicology, 1316 Biomedical Research Building (BRB) II/III, 421 Curie Boulevard, Philadelphia, PA, 19104-3083, USA
| | - G Ritacco
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - J Romine
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - N Sadekar
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - T W Schultz
- Member Expert Panel for Fragrance Safety, The University of Tennessee, College of Veterinary Medicine, Department of Comparative Medicine, 2407 River Dr., Knoxville, TN, 37996- 4500, USA
| | - D Selechnik
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - F Siddiqi
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - I G Sipes
- Member Expert Panel for Fragrance Safety, Department of Pharmacology, University of Arizona, College of Medicine, 1501 North Campbell Avenue, P.O. Box 245050, Tucson, AZ, 85724-5050, USA
| | - G Sullivan
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA.
| | - Y Thakkar
- Research Institute for Fragrance Materials Inc., 50 Tice Boulevard, Woodcliff Lake, NJ, 07677, USA
| | - Y Tokura
- Member Expert Panel for Fragrance Safety, The Journal of Dermatological Science (JDS), Editor-in-Chief, Professor and Chairman, Department of Dermatology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan
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Kik K, Bukowska B, Sicińska P. Polystyrene nanoparticles: Sources, occurrence in the environment, distribution in tissues, accumulation and toxicity to various organisms. Environ Pollut 2020; 262:114297. [PMID: 32155552 DOI: 10.1016/j.envpol.2020.114297] [Citation(s) in RCA: 171] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 02/17/2020] [Accepted: 02/28/2020] [Indexed: 05/14/2023]
Abstract
Civilization development is associated with the use of plastic. When plastic was introduced to the market, it was assumed that it was less toxic than glass. Recently, it is known that plastics are serious ecological problem they, do not degrade and remain in the environment for hundreds of years. Plastic may be degraded into micro-particles < 5000 nm in diameter, and further into nanoparticles (NPs) < 100 nm in diameter. NPs have been detected in air, soil, water and sludge. One of the most commonly used plastics is polystyrene (PS) - a product of polymerization of styrene monomers. It is used for the production of styrofoam and other products like toys, CDs and cup covers. In vivo and in vitro studies have suggested that polystyrene nanoparticles (PS-NPs) may penetrate organisms through several routes i.e. skin, respiratory and digestive tracts. They can be deposited in living organisms and accumulate further along the food chain. NPs are surrounded by "protein corona" that allows them penetrating cellular membranes and interacting with cellular structures. Depending on the cell type, NPs may be transported through pinocytosis, phagocytosis, or be transported passively. Currently there are no studies that would indicate a carcinogenic potential of PS-NPs. On the other hand, the PS monomer (styrene) was classified by the International Agency for Research on Cancer (IARC) as a potentially carcinogenic substance (carcinogenicity class B2). Despite of the widespread use of plastics and the presence of plastic NPs of secondary or primary nature, there are no studies that would assess the effect of those substances on human organism. This study was aimed at the review of the literature data concerning the formation of PS-NPs in the environment, their accumulation along the food chain, and their potential adverse effects on organisms on living various organization levels.
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Affiliation(s)
- Kinga Kik
- University of Lodz, Faculty of Biology and Environmental Protection, Department of Biophysics of Environmental Pollution, Pomorska 141/143 Str., 90-236 Lodz, Poland
| | - Bożena Bukowska
- University of Lodz, Faculty of Biology and Environmental Protection, Department of Biophysics of Environmental Pollution, Pomorska 141/143 Str., 90-236 Lodz, Poland
| | - Paulina Sicińska
- University of Lodz, Faculty of Biology and Environmental Protection, Department of Biophysics of Environmental Pollution, Pomorska 141/143 Str., 90-236 Lodz, Poland.
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Pilevar Z, Bahrami A, Beikzadeh S, Hosseini H, Jafari SM. Migration of styrene monomer from polystyrene packaging materials into foods: Characterization and safety evaluation. Trends Food Sci Technol 2019; 91:248-61. [DOI: 10.1016/j.tifs.2019.07.020] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Banton MI, Bus JS, Collins JJ, Delzell E, Gelbke HP, Kester JE, Moore MM, Waites R, Sarang SS. Evaluation of potential health effects associated with occupational and environmental exposure to styrene - an update. J Toxicol Environ Health B Crit Rev 2019; 22:1-130. [PMID: 31284836 DOI: 10.1080/10937404.2019.1633718] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
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.
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Affiliation(s)
- M I Banton
- a Gorge View Consulting LLC , Hood River , OR , USA
| | - J S Bus
- b Health Sciences , Exponent , Midland , MI , USA
| | - J J Collins
- c Health Sciences , Saginaw Valley State University , Saginaw , MI , USA
| | - E Delzell
- d Private consultant , Birmingham , AL , USA
| | | | - J E Kester
- f Kester Consulting LLC , Wentzville , MO , USA
| | | | - R Waites
- h Sabic , Innovative Plastics US LLC , Mount Vernon , IN , USA
| | - S S Sarang
- i Shell Health , Shell International , Houston , TX , USA
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Cruzan G, Bus JS, Andersen ME, Carlson GP, Banton MI, Sarang SS, Waites R. Based on an analysis of mode of action, styrene-induced mouse lung tumors are not a human cancer concern. Regul Toxicol Pharmacol 2018; 95:17-28. [DOI: 10.1016/j.yrtph.2018.02.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 02/14/2018] [Accepted: 02/15/2018] [Indexed: 02/06/2023]
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Abstract
The European Commission lists styrene (S) as an endocrine disruptor based primarily on reports of increased prolactin (PRL) levels in S-exposed workers. The US Environmental Protection Agency included S in its list of chemicals to be tested for endocrine activity. Therefore, the database of S for potential endocrine activity is assessed. In vitro and in vivo screening studies, as well as non-guideline and guideline investigations in experimental animals indicate that S is not associated with (anti)estrogenic, (anti)androgenic, or thyroid-modulating activity or with an endocrine activity that may be relevant for the environment. Studies in exposed workers have suggested elevated PRL levels that have been further examined in a series of human and animal investigations. While there is only one definitively known physiological function of PRL, namely stimulation of milk production, many normal stress situations may lead to elevations without any chemical exposure. Animal studies on various aspects of dopamine (DA), the PRL-regulating neurotransmitter, in the central nervous system did not give mechanistic explanations on how S may affect PRL levels. Overall, a neuroendocrine disruption of PRL regulation cannot be deduced from a large experimental database. The effects in workers could not consistently be reproduced in experimental animals and the findings in humans represented acute reversible effects clearly below clinical and pathological levels. Therefore, unspecific acute workplace-related stress is proposed as an alternative mode of action for elevated PRL levels in workers.
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Affiliation(s)
| | - Marcy Banton
- b Lyondell Chemical Company , Houston, Texas , USA
| | | | | | - Susan Leanne Samson
- e Division of Endocrinology, Department of Medicine , Baylor College of Medicine , Houston, Texas , USA
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Gelbke HP, Banton M, Faes E, Leibold E, Pemberton M, Duhayon S. Derivation of safe health-based exposure limits for potential consumer exposure to styrene migrating into food from food containers. Food Chem Toxicol 2014; 64:258-69. [DOI: 10.1016/j.fct.2013.11.039] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Revised: 11/25/2013] [Accepted: 11/26/2013] [Indexed: 11/30/2022]
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Rhomberg LR, Goodman JE, Prueitt RL. The Weight of Evidence Does Not Support the Listing of Styrene as "Reasonably Anticipated to be a Human Carcinogen" in NTP's Twelfth Report on Carcinogens. Hum Ecol Risk Assess 2013; 19:4-27. [PMID: 23335843 PMCID: PMC3545489 DOI: 10.1080/10807039.2012.650577] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 09/24/2011] [Indexed: 06/01/2023]
Abstract
Styrene was listed as "reasonably anticipated to be a human carcinogen" in the twelfth edition of the National Toxicology Program's Report on Carcinogens based on what we contend are erroneous findings of limited evidence of carcinogenicity in humans, sufficient evidence of carcinogenicity in experimental animals, and supporting mechanistic data. The epidemiology studies show no consistent increased incidence of, or mortality from, any type of cancer. In animal studies, increased incidence rates of mostly benign tumors have been observed only in certain strains of one species (mice) and at one tissue site (lung). The lack of concordance of tumor incidence and tumor type among animals (even within the same species) and humans indicates that there has been no particular cancer consistently observed among all available studies. The only plausible mechanism for styrene-induced carcinogenesis-a non-genotoxic mode of action that is specific to the mouse lung-is not relevant to humans. As a whole, the evidence does not support the characterization of styrene as "reasonably anticipated to be a human carcinogen," and styrene should not be listed in the Report on Carcinogens.
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Rueff J, Teixeira JP, Santos LS, Gaspar JF. Genetic effects and biotoxicity monitoring of occupational styrene exposure. Clin Chim Acta 2009; 399:8-23. [PMID: 18845133 DOI: 10.1016/j.cca.2008.09.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Revised: 09/15/2008] [Accepted: 09/16/2008] [Indexed: 11/22/2022]
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Abstract
To determine the effect of styrene on the male reproductive function of rats, male Wistar rats received a daily intraperitoneal (ip) injection of the xenobiotic at a dose of 600 mg/kg body weight. Serum testosterone (T) level was measured in duplicate by radioimmunoassay (RIA). Blood luteinizing hormone (LH) and follicle stimulating hormone (FSH) concentrations were determined using enzyme-linked immunosorbent assay (ELISA). After 10 days of treatment, an increase of the relative weight of the testis occurred, but that of the seminal vesicles and prostate remained unchanged compared to controls injected with an equivalent volume of the vehicle (corn oil). Serum T concentration dropped, while serum hypophyse hormone levels increased. Testicular histological observations revealed a pronounced morphological alteration, with enlarged intracellular spaces, loosening of tissue, and dramatic loss of gametes in the lumen of the seminiferous tubules. Spermatogenesis damage was also confirmed by the decrease in motility and the number of epididymal spermatozoa of treated rats. According to these results, with regard to the lack of a dose response relationship in this study, we may conclude that the testis, precisely the germinal and Sertoli cells, are the major targets for styrene toxicity.
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Affiliation(s)
- Naoufel Chamkhia
- Laboratoire de Physiologie Intégrée, Faculté des Sciences de Bizerte, 7021 Jarzouna, Tunisia
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Luderer U, Collins TFX, Daston GP, Fischer LJ, Gray RH, Mirer FE, Olshan AF, Setzer RW, Treinen KA, Vermeulen R. NTP-CERHR Expert Panel Report on the reproductive and developmental toxicity of styrene. ACTA ACUST UNITED AC 2006; 77:110-93. [PMID: 16345075 DOI: 10.1002/bdrb.20061] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Cruzan G, Faber WD, Johnson KA, Roberts LS, Hellwig J, Carney E, Yarrington JT, Stump DG. Two generation reproduction study of styrene by inhalation in Crl-CD rats. ACTA ACUST UNITED AC 2005; 74:211-20. [PMID: 15880800 DOI: 10.1002/bdrb.20041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study was conducted to evaluate the potential adverse effects of styrene on reproductive capability from whole-body inhalation exposure of F0 and F1 parental animals. Assessments included gonadal function, estrous cyclicity, mating behavior, conception rate, gestation, parturition, lactation, and weaning in the F0 and F1 generations, and F1 generation offspring growth and development. Four groups of male and female Crl:CD(SD)IGS BR rats (25/sex/group) were exposed to 0, 50, 150, and 500 ppm styrene for 6 hr daily for at least 70 consecutive days prior to mating for the F0 and F1 generations. Inhalation exposure for the F0 and F1 females continued throughout mating and gestation through gestation day 20. Inhalation exposure of the F0 and F1 females was suspended from gestation day 21 through lactation day 4. On lactation days 1 through 4, the F0 and F1 females received styrene in virgin olive oil via oral gavage at dose levels of 66, 117, and 300 mg/kg/day (divided into three equal doses, approximately 2 hr apart). These oral dosages were calculated to provide similar maternal blood peak concentrations as provided by the inhalation exposures. Inhalation exposure of the F0 and F1 females was re-initiated on lactation day 5. Styrene exposure did not affect survival or clinical observations. Rats in the 150- and 500-ppm groups in both parental generations gained weight more slowly than the controls. There were no indications of adverse effects on reproductive performance in either the F0 or F1 generation. Male and female mating and fertility indices, pre-coital intervals, spermatogenic endpoints, reproductive organ weights, lengths of estrous cycle and gestation, live litter size and postnatal survival were similar in all exposure groups. Additionally, ovarian follicle counts and corpora lutea counts for the F1 females in the high-exposure group were similar to the control values. No adverse exposure-related macroscopic pathology was noted at any exposure level in the F0 and F1 generations. A previously characterized pattern of degeneration of the olfactory epithelium that lines the dorsal septum and dorsal and medial aspects of the nasal turbinates occurred in the F0 and F1 generation animals from the 500-ppm group. In the 500-ppm group, F2 birthweights were reduced compared to the control and F2 offspring from both the 150- and 500-ppm exposure groups gained weight more slowly than the controls. Based on the results of this study, an exposure level of 50 ppm was considered to be the NOAEL for F0 and F1 parental systemic toxicity; the NOAEL for F0 and F1 reproductive toxicity was 500 ppm or greater.
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Cruzan G, Carlson GP, Johnson KA, Andrews LS, Banton MI, Bevan C, Cushman JR. Styrene respiratory tract toxicity and mouse lung tumors are mediated by CYP2F-generated metabolites. Regul Toxicol Pharmacol 2002; 35:308-19. [PMID: 12202046 DOI: 10.1006/rtph.2002.1545] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mice are particularly sensitive to respiratory tract toxicity following styrene exposure. Inhalation of styrene by mice results in cytotoxicity in terminal bronchioles, followed by increased incidence of bronchioloalveolar tumors, as well as degeneration and atrophy of nasal olfactory epithelium. In rats, no effects on terminal bronchioles are seen, but effects in the nasal olfactory epithelium do occur, although to a lesser degree and from higher exposure concentrations. In addition, cytotoxicity and tumor formation are not related to blood levels of styrene or styrene oxide (SO) as measured in chronic studies. Whole-body metabolism studies have indicated major differences in styrene metabolism between rats and mice. The major differences are 4- to 10-fold more ring-oxidation and phenylacetaldehyde pathways in mice compared to rats. The data indicate that local metabolism of styrene is responsible for cytotoxicity in the respiratory tract. Cytotoxicity is seen in tissues that are high in CYP2F P450 isoforms. These tissues have been demonstrated to produce a high ratio of R-SO compared to S-SO (at least 2.4 : 1). In other rat tissues the ratio is less than 1, while in mouse liver the ratio is about 1.1. Inhibition of CYP2F with 5-phenyl-1-pentyne prevents the styrene-induced cytotoxicity in mouse terminal bronchioles and nasal olfactory epithelium. R-SO has been shown to be more toxic to mouse terminal bronchioles than S-SO. In addition, 4-vinylphenol (ring oxidation of styrene) has been shown to be highly toxic to mouse terminal bronchioles and is also metabolized by CYP2F. In human nasal and lung tissues, styrene metabolism to SO is below the limit of detection in nearly all samples, and the most active sample of lung was approximately 100-fold less active than mouse lung tissue. We conclude that styrene respiratory tract toxicity in mice and rats, including mouse lung tumors, are mediated by CYP2F-generated metabolites. The PBPK model predicts that humans do not generate sufficient levels of these metabolites in the terminal bronchioles to reach a toxic level. Therefore, the postulated mode of action for these effects indicates that respiratory tract effects in rodents are not relevant for human risk assessment.
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17
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Abstract
Concerns of a tumorigenic risk of styrene (ST) originate from the findings that styrene (ST) is metabolized to the genotoxic intermediate styrene-7,8-oxide (SO). Therefore, it was hypothesized that results of animal long-term studies with ST and SO together with the SO tissue burden are sufficient for conducting a 'worst case' estimate of the tumorigenic risk of ST. On this basis we predicted the excess human lifetime risk for lung tumors (p(EXL)) and the highest possible risk for other systemic tumors (p(HPS)) resulting from daily intake of ST via food and ambient air. As measures for p(EXL) the mean lifetime concentration of SO in the transitional zone of the lung and for p(HPS) the mean lifetime concentration of SO in blood were calculated using a physiological toxicokinetic model. For a daily oral intake of 12 microST, p(EXL) was obtained to be between 5x10(-9) and 2x10(-8) and p(HPS) to be between 7x10(-9) and 2x10(-8). Lifetime risks calculated for continuous exposure to 3 microg/m(3) ST in ambient air were between 8x10(-7) and 3x10(-6) (p(EXL)) and between 2x10(-8) and 4x10(-8) (p(HPS)). Although these values indicate very low risks, the actual risks are expected to be even by far smaller. This is discussed in detail for lung tumorigenesis.
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Affiliation(s)
- Johannes G Filser
- GSF-Institute of Toxicology, Ingolstaedter Landstrasse 1, D-85764, Neuherberg, Germany.
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Cohen JT, Carlson G, Charnley G, Coggon D, Delzell E, Graham JD, Greim H, Krewski D, Medinsky M, Monson R, Paustenbach D, Petersen B, Rappaport S, Rhomberg L, Ryan PB, Thompson K. A comprehensive evaluation of the potential health risks associated with occupational and environmental exposure to styrene. J Toxicol Environ Health B Crit Rev 2002; 5:1-265. [PMID: 12012775 DOI: 10.1080/10937400252972162] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Affiliation(s)
- Joshua T Cohen
- Harvard Center for Risk Analysis, Harvard School of Public Health, Boston, Massachusetts, USA
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Date K, Ohno K, Azuma Y, Hirano S, Kobayashi K, Sakurai T, Nobuhara Y, Yamada T. Endocrine-disrupting effects of styrene oligomers that migrated from polystyrene containers into food. Food Chem Toxicol 2002; 40:65-75. [PMID: 11731037 DOI: 10.1016/s0278-6915(01)00096-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The endocrine-disrupting effects of styrene dimers (SD: NSD-01, -08 and -09) and styrene trimers (ST: NST -01, -03 and -12), which migrated from polystyrene (PS) containers into instant food, were investigated together with styrene monomer (SM) using in vitro and in vivo assays. In the estrogen (ER) and androgen receptor (AR) binding assay, SM, SD and ST showed no binding activity at concentration of 10(-10)-10(-5) mol/l. In order to evaluate the estrogenic activity in vivo, the uterotrophic assay was conducted. When prepubertal and ovariectomized adult rats were dosed with SM, SD and ST for 3 days by subcutaneous injection, these compounds did not induce significant increase in uterine weight. Additionally, to evaluate anti-androgen activity in vivo, the Hershberger assay for anti-androgenic activity in the presence of testosterone treatment was conducted. When castrated, testosterone-treated immature male rats were dosed SM, SD and ST for 7 days by oral gavage, these compounds did not induce a decrease in the seminal vesicle, ventral prostate and levator ani plus bulbocavernosus muscle weights. To evaluate the effects on hormones other than sex hormones, the thyroid hormone receptor (TR) binding assay and rat serum prolactin (PRL) was conducted. In the TR binding assay, SM, SD and ST showed no binding activity at a concentration of 10(-5) mol/l. When ovariectomized rats were dosed with SM, SD and ST for 3 days by sc injection, the results showed there was no change in rat serum PRL. From the above these results, we concluded that SM, SD and ST exhibit no apparent estrogenic, androgenic, anti-androgenic and thyroid activity.
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Affiliation(s)
- K Date
- Central Research Institute, Nissin Food Products Co., Ltd, 2247, Noji-Cho, Shiga 525-0055, Kusatsu, Japan.
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20
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Katakura Y, Kishi R, Ikeda T, Miyake H. Effects of prenatal styrene exposure on postnatal development and brain serotonin and catecholamine levels in rats. Environ Res 2001; 85:41-47. [PMID: 11161651 DOI: 10.1006/enrs.2000.4053] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Maternal reproductive effects in Wistar rats exposed to 0, 50, or 300 ppm styrene for 6 h/day during gestational days 6 to 20 were evaluated. Their offspring were observed postnatally for neurochemical changes, growth, and physical landmarks of development. Mothers exposed to styrene were compared with pair-fed and ad-lib-fed controls in order to adjust nutrient conditions. Prolongation of the gestational period, food intake, and the number of neonatal deaths or stillbirths in 300-ppm-exposed dams showed evidence of styrene-related effects. Other reproductive parameters, such as litter size, birth weight, and sex ratio, were found to exhibit no effects within the variation range studied. A neurochemical effect was observed in that the 5-HT and HVA concentrations in cerebrum were significantly decreased. Incisor eruption (mandible), eye opening, and the air-righting reflex were delayed in rat pups born to dams receiving 300 ppm styrene exposure compared with the pair-fed and ad lib control groups. Pups born to dams exposed to 50 ppm styrene also had a significantly delayed air-righting reflex compared with ad lib controls. These results suggest that the offspring were susceptible to the effects of styrene on a few developmental landmarks even when nutritional effects were controlled.
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Affiliation(s)
- Y Katakura
- Department of Public Health, Sapporo Medical University, Sapporo 060-8556, Japan
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21
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Abstract
The reproductive and developmental toxicity of styrene has been studied in animals and humans. The animal studies on styrene have diverse study designs and conclusions. Developmental or reproductive toxicity studies have been conducted in rats, mice, rabbits, and hamsters. In most cases, high doses are required to elicit effects, and the effects are not unique to reproduction or development. In a number of the reports, either the experimental designs are limited or the descriptions of the designs and the endpoints measured are insufficient to draw conclusions about the toxicity of styrene. The more complete and better-reported studies show that styrene does not cause developmental toxicity at dose levels that are not maternally toxic. Some neurochemical or neurobehavioral effects have been reported at high exposures. Styrene does not affect fertility or reproductive function. Considerable animal toxicity data on styrene support the conclusion that styrene is neither an endocrine-active substance nor an endocrine disrupter. Human studies often suffer from either inadequate exposure data or exposure to a wide variety of materials, so that attribution of effects to styrene exposure is impossible. Furthermore, investigators often have failed to account for other exposures in the workplace or for other potentially confounding factors in their studies. Menstrual cycle irregularities and congenital abnormalities were initially reported; however, the better and more recent reports do not show that styrene causes developmental or reproductive effects in humans. Human studies also support the conclusion that styrene is not an endocrine disrupter. Although some study authors have concluded that styrene is either a human or an animal reproductive or developmental toxicant, careful review demonstrates that such conclusions are not justified.
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Affiliation(s)
- N A Brown
- MRC Experimental Embryology and Teratology Unit, St. George's Hospital Medical School, University of London, SW17 0RE, United Kingdom
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22
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Abstract
The etiology of male infertilities is largely undetermined, and our knowledge of exogenous factors affecting the male reproductive system is still limited. In particular, the role of specific environmental and occupational factors is incompletely elucidated. Various occupational (physical and chemical) agents have been shown to affect male reproductive functions in animals, but large differences in reproductive function and/or xenobiotic handling between species limit extrapolation to humans. When available, human data are often conflicting and, except in a few instances, usually refer to broad and heterogenous occupational categories or to groups of agents (e.g., solvents). It is often difficult to elucidate the role of a single agent because occupational exposure conditions are often complex and various confounding factors related to lifestyle (smoking, alcohol, and diet) or socioeconomic state may also affect sperm quality, fertility, or pregnancy outcomes. The objective of this work is to summarize the main epidemiological and, where relevant, experimental findings pertaining to agents (physical and chemical) encountered in the occupational environment that might affect the male reproductive system (sperm count, motility and morphology, libido, and fertility) and/or related pregnancy outcomes (spontaneous abortion, stillbirth, low birth weight, and birth defects and childhood malignancy in offspring). Some methodological issues related to research on the reproductive effects of toxicants are also discussed briefly.
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Affiliation(s)
- S Tas
- Industrial Toxicology and Occupational Medicine Unit, School of Medicine, Catholic University of Louvain, Brussels, Belgium
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23
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Kishi R, Chen BQ, Katakura Y, Ikeda T, Miyake H. Effect of prenatal exposure to styrene on the neurobehavioral development, activity, motor coordination, and learning behavior of rats. Neurotoxicol Teratol 1995; 17:121-30. [PMID: 7760773 DOI: 10.1016/0892-0362(94)00060-q] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Maternal Wistar rats were exposed via inhalation to 0, 50, or 300 ppm styrene for 6 h/day during gestation days 7 to 21, and offspring were subsequently evaluated in several neurobehavioral tests. Preliminary results with a small number of litters revealed significant dose-dependent effects in tests performed prior to weaning (surface righting, pivoting locomotion, and bar holding), as well as in tests performed after weaning (motor coordination, open-field behavior, and motor activity). Exposure to low concentrations of styrene (50 ppm) caused disturbances in motor coordination in addition to delaying some motor and reflex developments. Large doses (300 ppm) led to changes in open-field behavior and increases in spontaneous activity in addition to the delay in neurobehavioral developments. Exposure of dams to styrene did not clearly affect the learning behavior of the offspring. It was also observed that age played a role in the differences in styrene's effects on neurobehavioral function. Only subtle effects were found in both open-field behavior and motor-coordination function when compared with control rats at 120 days of age. These results suggest that the functional neurobehavioral development of progeny of dams exposed to styrene (or other solvents) should be further investigated.
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Affiliation(s)
- R Kishi
- Department of Public Health, Sapporo Medical College, Japan
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Abstract
Styrene is efficiently metabolized to styrene oxide, which is itself readily detoxified by the same enzymes as those involved in the metabolism of various foodstuffs. Styrene oxide, like many intermediate metabolites of foodstuffs, is genotoxic and, if introduced directly into the stomachs of rodents in high doses/concentrations, gives rise to cancers of the forestomach. Exposing mice to doses of styrene high enough to overwhelm the capacity of the body to detoxify styrene oxide has been reported to increase lung tumor incidence in mice. The findings in eight epidemiological studies provide reassurance that occupational exposure to styrene is not associated with increased cancer risk. Tests for reproductive toxicity have given negative results, but effects on blood dopamine and hypothalamic and pituitary function and menstrual cycling under conditions of very high exposure have been reported. In light of all the available information, it is concluded that migration of styrene from food-wrapping materials is not a matter for toxicological concern.
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Affiliation(s)
- F J Roe
- Independent Consultant in Toxicology and Cancer Research, London, U.K
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25
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Abstract
Eleven long-term toxicity studies were reviewed on styrene and five on styrene oxide in an effort to evaluate the potential carcinogenic activity of these chemicals in animals. The styrene studies included inhalation exposure (rats, mice, guinea pigs, and rabbits), intragastric gavage (rats and mice), drinking water (rats), and intraperitoneal injection (rats), while styrene oxide exposure was via intragastric gavage (rats and mice) or skin painting (mice). Each study was reviewed and evaluated for details and adequacy of design, adequacy of reported data, and interpretation. The results of this review are 1. There was no convincing evidence of carcinogenic activity of styrene in animals, although many of the studies were considered inadequate. 2. Styrene oxide was carcinogenic to the forestomach of both sexes of rats and mice after gavage exposure and was associated with an increase in liver neoplasms in male mice in one study. No carcinogenic activity was observed in mice after dermal exposure (skin paint). 3. None of the studies of styrene or styrene oxide reported here are well suited for extrapolating potential carcinogenic activity of either compound to humans because all have deficiencies in design, conduct, interpretation, or utilized a less than ideal route of exposure. A chronic state-of-the-art inhalation study is needed to evaluate this aspect of hazard assessment.
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Affiliation(s)
- E E McConnell
- School of Public Health, University of North Carolina, Chapel Hill 27599
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26
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Abstract
Styrene was evaluated for the reproductive effects of pregnant rats and the neurochemical effects in the offspring of rats exposed during gestation. Pregnant Wistar rats were exposed to 0, 50, or 300 ppm styrene for 6 h/day during days 7 to 21 of gestation. No significant differences in the number of offspring delivered were observed between the exposed and control groups. Body weights at 1 day of age of the offspring whose mothers were exposed to styrene were significantly lower than those of the control group. Although, there were neither statistically significant differences of protein contents nor brain weights among styrene-exposed and their control offsprings of rats, analyses of neurotransmitter studies showed dose-dependent decreases of neuroamines, especially 5-HT (serotonin) and its metabolite 5HIAA (5-hydroxyindoleacetic acid) in the newborn offspring of styrene-exposed rats. The results suggest that gestational exposure to styrene at these concentrations does not produce apparent reproductive toxicity but affects the body weight of pups and causes lowering of the neurotransmitter levels in the brain.
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Affiliation(s)
- R Kishi
- Department of Public Health, Sapporo Medical College, Japan
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27
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Daston GP, Overmann GJ, Taubeneck MW, Lehman-McKeeman LD, Rogers JM, Keen CL. The role of metallothionein induction and altered zinc status in maternally mediated developmental toxicity: comparison of the effects of urethane and styrene in rats. Toxicol Appl Pharmacol 1991; 110:450-63. [PMID: 1949013 DOI: 10.1016/0041-008x(91)90046-h] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We hypothesize that maternal metallothionein (MT) induction by toxic dosages of chemicals may contribute to or cause developmental toxicity by a chain of events leading to a transient but developmentally adverse decrease in Zn availability to the embryo. This hypothesis was tested by evaluating hepatic MT induction, maternal and embryonic Zn status, and developmental toxicity after exposure to urethane, a developmental toxicant, or styrene, which is not a developmental toxicant. Pregnant Sprague-Dawley rats were given 0 or 1 g/kg urethane ip, or 0 or 300 mg/kg styrene in corn oil po, on Gestation Day 11 (sperm positive = Gestation Day 0). These were maternally toxic dosages. As both treatments decreased food consumption, separate pair-fed control groups were also evaluated for effects on MT and Zn status and development. In addition, Gestation Day 11 rat embryos were exposed to urethane in vitro in order to determine whether urethane has the potential to be directly embryotoxic. Urethane treatment induced hepatic MT 14-fold over control; styrene treatment induced MT 2.5-fold. The MT induction by styrene could be attributed to decreased food intake, as a similar level of induction was observed in a pair-fed untreated control group. However, the level of MT induction by urethane was much greater than that produced by decreased food intake alone. Hepatic Zn concentration, particularly in the cytosol, was increased in the presence of increased hepatic MT concentration. Plasma Zn concentration was significantly decreased (approximately 30%) by urethane treatment, but not by styrene or food restriction (pair-feeding). Distribution of 65Zn to the liver of urethane-treated dams was significantly greater (by 30%), while distribution to embryonic tissues was significantly lower (by at least 50%) than in pair-fed or ad lib.-fed controls. Styrene treatment had no effect on 65Zn distribution. Urethane was developmentally toxic, causing an 18% decrease in fetal weight and a significant delay in skeletal ossification, but was not toxic to rat embryos in vitro. Styrene was not developmentally toxic. The changes observed after urethane treatment, namely substantial hepatic MT induction and altered maternal and embryonic Zn status, along with the lack of direct embryotoxicity of urethane in vitro, support the hypothesis that these maternal effects contribute to developmental toxicity. The lack of similar changes in styrene-intoxicated dams provides one explanation for its low developmental toxicity at maternally toxic dosages.
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Affiliation(s)
- G P Daston
- Miami Valley Laboratories, Procter & Gamble Company, Cincinnati, Ohio 45239
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Affiliation(s)
- N A Brown
- MRC Experimental Embryology and Teratology Unit, St. George's Hospital Medical School, University of London, U.K
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29
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Abstract
Styrene is used in the production of plastics and resins, which include polystyrene resins, acrylonitrile-butadiene-styrene resins, styrene-acrylonitrile resins, styrene-butadiene copolymer resins, styrene-butadiene rubber, and unsaturated polyester resins. In 1985, styrene ranked in the top ten of synthetic organic chemicals produced in the U.S. This review focuses on various aspects of styrene toxicology including acute and chronic toxicity, carcinogenicity, genotoxicity, pharmacokinetics, effects on hepatic and extrahepatic xenobiotic-metabolizing enzymes, pharmacokinetic modeling, and covalent interactions with macromolecules. There appear to be many similarities between the toxicity and metabolism of styrene in rodents and humans. Needed areas of future research on styrene include studies on the molecular dosimetry of styrene in terms of both hemoglobin and DNA adducts. The results of such research should improve our ability to assess the relationship between exposure to styrene and surrogate measures of "effective dose", thereby improving our ability to estimate the effects of low-level human exposures.
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Affiliation(s)
- J A Bond
- Inhalation Toxicology Research Institute, Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico
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