Quantitative structure‐activity relationships of nonspecific and specific toxicants in several organism species

Ikemoto, Yuji; Motoba, Kazuhiko; Suzuki, Takashi; Uchida, Matazaemon

doi:10.1002/etc.5620110706

Cited by 21 publications

(5 citation statements)

References 34 publications

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“…This may be due to a rapid hydrolysis and/or biotransformation of the parent compound by the organism. In case of aquatic toxicity, it was shown that a rapid degradation of the parent compound to a non-toxic metabolite decreased the compounds toxicity below its calculated baseline toxicity [17].…”

Section: Resultsmentioning

confidence: 99%

Application of QSARs: Correlation of Acute Toxicity in the Rat Following Oral or Inhalation Exposure

Wolf¹,

Lieder

Walker

2004

QSAR Comb. Sci.

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Quantitative Structure-Activity Relationships (QSARs) based upon a lethal narcosis mechanism represent baseline or minimum toxicity, i.e. unless a chemical acts by a more specific mechanism, its toxicity will be predicted by such models. Baseline toxicity should be independent of exposure route. A toxicity ratio (TR) is defined as the ratio of the calculated baseline toxicity over the experimentally determined value. A TR-value of approx. 1 indicates baseline toxicity. A TR-value greater than 1 indicates excess toxicity due to the existence of a more specific mechanism of action. We investigated the possibility of extrapolation from the inhalation route to the oral route by applying the above concepts. We report the TR-values for a set of chemicals with measured LD 50 and LC 50 -values obtained from the Registry of Toxic Effects of Chemical Substances (RTECS) and calculated toxicity values based on a previously developed oral and inhalation baseline-toxicity models. For part of the compounds the reliability of the TR-values may be questionable either due to errors in the measured toxicity values, or due to extrapolation of the baseline-toxicity models outside their range of proven validity. For 47% of the remaining compounds, the TR-value for both exposure routes was approx. 1. For 22% of the remaining compounds a specific mechanism of toxicity was indicated by a TR-value greater than 1, and another 22% appeared to have a specific mechanism of action for only one of the exposure routes. It is concluded that after establishing a lethal narcosis mechanism through inhalation exposure the compound×s oral toxicity can be reliably estimated. In case of more specific toxicities, the calculated oral baseline toxicity can be used to determine the upper limits in the toxicity experiment.

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Section: Resultsmentioning

confidence: 99%

Application of QSARs: Correlation of Acute Toxicity in the Rat Following Oral or Inhalation Exposure

Wolf¹,

Lieder

Walker

2004

QSAR Comb. Sci.

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“…Regression analysis of both log(BCFD) and C2 with respect to logKow revealed that linear expressions can be used to describe the relationships between logKow and log(BCFD) as well as Cs (Figs.5 a, d). The linear correlation of log(BCFB) with logKow has generally been observed for the bioconcentration of HOCs in aquatic organisms (Chiou, 1985;Geyer et al, 1984;Mailhot, 1987;Ikemoto et al, 1992;Manthey et aL, 1993). The values of k l and k2 tend to follow 'biphasic' relationships with Kow ( where a0, al, b0 and bl are constants depending on the volume of the organism, the lipid fraction of the organism and the 'chemical conductivity' in the lipid or water phase (Gobas et al, 1991).…”

Section: 2 Correlation Of Bcfm Kl K2 and C~ With Kowmentioning

confidence: 91%

A model describing the time course and variability in toxicity of hydrophobic chemicals to aquatic organisms

Wang

Shan

Ming

et al. 2002

J Ocean Univ. China

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The growth of Chlorella marine, Nannochloris oculate, Pyramimonaos sp., Platymonas subcordiformis and Phaeodactylum trieornutum exposed to chlorobenzene, 1,2-dichlorobenzene, 1, 2, 3, 4-tetrachlorobenzene and pentaehlorobenzene was tested. The Boltzman equation was used to describe organism growth. The time course for uptake of hydrophobic organic chemicals (HOCs) by aquatic organisms was expressed by incorporating growth and, if desired, the effect of metabolism into the HOC bioconcentration process. The probability of any given concentration of HOCs in the organisms causing a specified toxic endpoint was expressed with a modified Weibull distribution function. The combined bioconcentration and probability equations were tested with data for time course of incubation of algae exposed to chlorinated benzenes (CBs). A set of parameters, including the uptake rate constant kt, the elimination rate constant kz and thereafter the bioconcentration factor on a dry weight basis, BCFD, the critical HOC concentration in the organism resulting in a specified toxic endpoint, C/], and the spread factor, S, could be obtained by fitting only experimental data for percent growth inhibition(%)-time-CB exposure concentration. The average coefficients of variation within CBs were 15.2% for BCFD, 21.0% for kl, 18.3% for k2, 8.1% for C~ and 9.7% for S. The variability in toxicity (such as EC10, EC50, EC90) derived from the model equations agreed well with those experimentally observed.

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“…It is a highly persistent organochlorine compound, strongly adhering to soil particles. It is quite toxic to aquatic organisms, according to Ikemoto et al (1992) the LC50 values for daphnids and fish are below 0.1 mg/L. Similarly, Jarvinen et al (1988) reported very high toxicity of endrin to fish, with a 96-hour LC50 of less than 0.001 mg/L for fathead minnows.…”

Section: Persistent Organochlorine Compoundsmentioning

confidence: 99%

Advances in the Development of Procedures to Establish the Toxicity of Non-Extractable Residues (NER) in Soil. LRI-ECO25

Harmsen

Hennecke

Hund‐Rinke

et al. 2018

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There is already a long discussion around the bioavailability and ecotoxicological relevance of Non Extractable Residues (NER) in soil. Is NER formation a detoxification process or should it be considered a hidden hazard? NER can only be established using labelled chemicals (e.g. 14 C) and cannot be measured with conventional chemical analytics. Regulations ask for understandable and measurable parameters. Considered in the developed tool are three measurable parameters: 1) Chemical present in the water phase, 2) A potentially available fraction in equilibrium with the water phase. 3) The total extractable amount. NER is considered, but mentioned as non-measurable and non-bioavailable. The fates of three NER-forming chemicals were followed in a period of 6 months after addition also using 14 C chemicals. For the chemical Tri-NitroToluene (TNT), NER-formation was reproducible and NER formation during aging removed toxicity. By removing the bioavailable fractions directly after spiking and after aging it was also possible to remove toxicity. The experiments showed that toxicity was caused by the bioavailable chemical and not by NER. With Cypermethrin and Carbendazim, results were less clear, because there was a large uncertainty in NER-formation. The degree of biodegradation was not reproducible for Cypermethrin and unexpected losses occurred with Carbendazim and it is not possible to draw conclusions from only a non-labelled experiments.

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Quantitative structure‐activity relationships of nonspecific and specific toxicants in several organism species

Cited by 21 publications

References 34 publications

Application of QSARs: Correlation of Acute Toxicity in the Rat Following Oral or Inhalation Exposure

Application of QSARs: Correlation of Acute Toxicity in the Rat Following Oral or Inhalation Exposure

A model describing the time course and variability in toxicity of hydrophobic chemicals to aquatic organisms

Advances in the Development of Procedures to Establish the Toxicity of Non-Extractable Residues (NER) in Soil. LRI-ECO25

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