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PT15 Alkylphenols and Alkylphenol Ethoxylates
(PT227) Toxicities of Four Alkylphenols to Microbes, Daphnids, and Fish, and their QSAR.
Choi, K1, Chung, M-H1, Zoh, K1, Meier, P2, 1 Seoul National University, Seoul, Korea2 University of Michigan, Ann Arbor, MI, USA
ABSTRACT- Acute and chronic toxicities of four alkylphenols (3-tert-butyl-, 2-isopropyl-, 3-isopropyl-, and 4-isopropylphenol) were evaluated with Microtox, Ceriodaphnia dubia, and fathead minnows. Common use of these alkylphenols includes lube oil additives, oil demulsifiers, antioxidants, and the manufacture of surface-active agents, plasticizers, and phenolic resins. Response to the exposure was different among test organisms and exposure durations: For Vibrio fischeri, 4-isopropylphenol exhibited the greatest relative toxicity (EC5015min of 0.01 mg/L), followed by 3-tert-butyl-(0.1), 3-isopropyl-(0.3), and 2-isopropylphenol (2.8). With daphnids and fish, the responses were less sensitive, and not as significantly different among the alkylphenols. For Ceriodaphnia 48 hr exposure, the most toxic compound to the least was as follows: 3-isopropyl-(EC50 of 7.2 mg/L), 4-isopropyl-(10.1), 2-isopropyl-(10.5), and 3-tert-butylphenol (12.2). For acute fish tests, toxicities (LC50 in mg/L) were ranked in decreasing order as follows: 4-isopropyl-(5.5), 3-tert-butyl-(7.2), 2-isopropyl-(8.4), and 3-isopropylphenol (13.1). For chronic Ceriodaphnia tests, IC25 (mg/L) was the lowest for 4-isopropyl-(1.1), then followed by 2-isopropyl-(1.2), 3-isopropyl-(2.0), and 3-tert-butylphenol (2.9). Chronic fish IC25s were around 2.1-3.4 mg/L, and significant differences were not noted. Acute-to-chronic ratios of these compounds ranged from 1.6 to 4.2 for fish, and 3.5 to 9.5 for Ceriodaphnia. Literatures indicate relative electrophilicity (ELUMO) is negatively correlated with toxicities of polar narcotics to ciliates and fish. However, our results from Microtox and acute fish tests showed the opposite: V. fischeri and fathead minnows were more susceptible to the alkylphenols with higher ELUMO. This finding suggests another mode of action may be present with the alkylphenols for Micortox and fathead minnows.
Key words: QSAR, alkylphenols, water, toxicity
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