Quantitative structure-activity relationships in fish toxicity studies Part 2: The influence of pH on the QSAR of chlorophenols

PENTACHLOROPHENOL TOXICITY TO AMPHIPODS AND FATHEAD MINNOWS AT DIFFERENT TEST pH VALUES

“…These findings are consistent with the relationship between the log n-octanol/water partition coefficient (log P ) , which measures relative lipophilicity and BCF [34] and between l o g P and pH [35]. Toxicity and the mechanism of uptake and elimination of chlorophenols in fish and their relationship to log P , pK, and pH has been discussed by Konemann and Musch [33] and Saarikoski and Viluksela [31]. Because both the toxicity and accumulation of PCP decreased with increased pH in these studies, the reduction in both acute and chronic toxicity in fish at higher values of pH appears to result from the fish not accumulating PCP to concentrations that cause adverse effects as readily as at low pH.…”

PENTACHLOROPHENOL TOXICITY TO AMPHIPODS AND FATHEAD MINNOWS AT DIFFERENT TEST pH VALUES

“…These findings are consistent with the relationship between the log n-octanol/water partition coefficient (log P ) , which measures relative lipophilicity and BCF [34] and between l o g P and pH [35]. Toxicity and the mechanism of uptake and elimination of chlorophenols in fish and their relationship to log P , pK, and pH has been discussed by Konemann and Musch [33] and Saarikoski and Viluksela [31]. Because both the toxicity and accumulation of PCP decreased with increased pH in these studies, the reduction in both acute and chronic toxicity in fish at higher values of pH appears to result from the fish not accumulating PCP to concentrations that cause adverse effects as readily as at low pH.…”

Toxic Ratio as an Indicator of the Intrinsic Toxicity in the Assessment of Persistent, Bioaccumulative, and Toxic Chemicals

“…Under the assumption that the slope in eq 7 is equal to -1, ILC 50,bl is constant for chemicals with log Kow > 1. On the other hand, if the slope of the relationship between log LC50 and log Kow is determined as a regression parameter, a value of -0.87 is obtained, which is similar to the slopes found in other toxicity baselines (4,26,40,56,65) (see Supporting Information). In this case, ILC50,bl is not exactly constant for different values of Kow but varies between 3.2 (log Kow ) 1) and 13.8 mmol/kg (log Kow ) 6).…”

Fish acute toxicity syndromes and their use in the QSAR approach to hazard assessment.

“…(1) (Fig. 2): log LC50 = -0.94 logP + 0.94 log (0.000068 logP + 1) -1.25 (1) (r2 = 0.9936) Similar relationships with the guppy (33) and Daphnia magna (34) have been reported as well. Also presented in Figures 1 and 2 is the relationship between water solubility and log P, which delineates the "aquatic toxicity space" as that region below water solubility; i.e., acute toxicity cannot be measured under equilibrium conditions at concentrations greater than aqueous solubility (25).…”

PENTACHLOROPHENOL TOXICITY TO AMPHIPODS AND FATHEAD MINNOWS AT DIFFERENT TEST pH VALUES

“…These findings are consistent with the relationship between the log n-octanol/water partition coefficient (log P ) , which measures relative lipophilicity and BCF [34] and between l o g P and pH [35]. Toxicity and the mechanism of uptake and elimination of chlorophenols in fish and their relationship to log P , pK, and pH has been discussed by Konemann and Musch [33] and Saarikoski and Viluksela [31]. Because both the toxicity and accumulation of PCP decreased with increased pH in these studies, the reduction in both acute and chronic toxicity in fish at higher values of pH appears to result from the fish not accumulating PCP to concentrations that cause adverse effects as readily as at low pH.…”

Toxic Ratio as an Indicator of the Intrinsic Toxicity in the Assessment of Persistent, Bioaccumulative, and Toxic Chemicals

“…Under the assumption that the slope in eq 7 is equal to -1, ILC 50,bl is constant for chemicals with log Kow > 1. On the other hand, if the slope of the relationship between log LC50 and log Kow is determined as a regression parameter, a value of -0.87 is obtained, which is similar to the slopes found in other toxicity baselines (4,26,40,56,65) (see Supporting Information). In this case, ILC50,bl is not exactly constant for different values of Kow but varies between 3.2 (log Kow ) 1) and 13.8 mmol/kg (log Kow ) 6).…”

Fish acute toxicity syndromes and their use in the QSAR approach to hazard assessment.

“…(1) (Fig. 2): log LC50 = -0.94 logP + 0.94 log (0.000068 logP + 1) -1.25 (1) (r2 = 0.9936) Similar relationships with the guppy (33) and Daphnia magna (34) have been reported as well. Also presented in Figures 1 and 2 is the relationship between water solubility and log P, which delineates the "aquatic toxicity space" as that region below water solubility; i.e., acute toxicity cannot be measured under equilibrium conditions at concentrations greater than aqueous solubility (25).…”

PENTACHLOROPHENOL TOXICITY TO AMPHIPODS AND FATHEAD MINNOWS AT DIFFERENT TEST pH VALUES

“…These findings are consistent with the relationship between the log n-octanol/water partition coefficient (log P ) , which measures relative lipophilicity and BCF [34] and between l o g P and pH [35]. Toxicity and the mechanism of uptake and elimination of chlorophenols in fish and their relationship to log P , pK, and pH has been discussed by Konemann and Musch [33] and Saarikoski and Viluksela [31]. Because both the toxicity and accumulation of PCP decreased with increased pH in these studies, the reduction in both acute and chronic toxicity in fish at higher values of pH appears to result from the fish not accumulating PCP to concentrations that cause adverse effects as readily as at low pH.…”

Toxic Ratio as an Indicator of the Intrinsic Toxicity in the Assessment of Persistent, Bioaccumulative, and Toxic Chemicals

“…Under the assumption that the slope in eq 7 is equal to -1, ILC 50,bl is constant for chemicals with log Kow > 1. On the other hand, if the slope of the relationship between log LC50 and log Kow is determined as a regression parameter, a value of -0.87 is obtained, which is similar to the slopes found in other toxicity baselines (4,26,40,56,65) (see Supporting Information). In this case, ILC50,bl is not exactly constant for different values of Kow but varies between 3.2 (log Kow ) 1) and 13.8 mmol/kg (log Kow ) 6).…”

Fish acute toxicity syndromes and their use in the QSAR approach to hazard assessment.

“…(1) (Fig. 2): log LC50 = -0.94 logP + 0.94 log (0.000068 logP + 1) -1.25 (1) (r2 = 0.9936) Similar relationships with the guppy (33) and Daphnia magna (34) have been reported as well. Also presented in Figures 1 and 2 is the relationship between water solubility and log P, which delineates the "aquatic toxicity space" as that region below water solubility; i.e., acute toxicity cannot be measured under equilibrium conditions at concentrations greater than aqueous solubility (25).…”