4 ms·

Actually the conservative estimate in humans, according to Wikipedia is 0.5–1.0 mg/kg. Rats are a lot tougher than humans.

ekianjo 8y ago
Wikipedia is not the place you should look for reliable toxicological information. There are better places online (and free of access, too). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880486/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880486/ > Although an LD50 of 0.8 mg/kg would implicate that the toxicity of nicotine is similar to or even higher than that of cyanide, fatal nicotine intoxications are relatively rare, and there are countless records of subjects who survived consumption of nicotine in amounts far higher than 60 mg (Larson et al. 1961). The most drastic example is probably survival of a suicide attempt with 4 g of pure nicotine (Schmidt 1931). While this is certainly an exceptional case, in which the amount of bioavailable nicotine was markedly reduced by vomiting, ingestion of tobacco or nicotine gums at doses up to 6 mg/kg nicotine was reported to evoke symptoms of intoxication without causing death (Malizia et al. 1983; Smolinske et al. 1988). These and many other literature reports on nonfatal nicotine intoxications are hardly compatible with a lethal dose of 60 mg or less. > Several detailed reviews are available on fatal nicotine intoxications caused by either suicidal intent or accidents, latter mainly resulting from misusage of nicotine-containing solutions marketed as pesticides (Esser and Kühn 1933; Larson et al. 1961; Maehly and Bonnichsen 1963; Tiess and Nagel 1966; Hayes 1982; Corkery et al. 2010; Solarino et al. 2010). The postmortem data reviewed by Maehly and Bonnichsen (1963) and more recently by Corkery et al. (2010) and Solarino et al. (2010) revealed minimal nicotine blood levels of 2 mg/L, but rapid decline of blood nicotine after death (Sanchez et al. 1996) may have led to underestimation of the actual lethal concentration in delayed autopsies. > Despite these uncertainties and the complex pharmacokinetics of nicotine (Hukkanen et al. 2005), a rough estimate of the amount of ingested nicotine from postmortem analyses of blood levels appears feasible. Smoking a cigarette results in uptake of approximately 2 mg of nicotine and gives rise to mean arterial plasma concentrations of about 0.03 mg/L (30 ng/ml) (Gourlay and Benowitz 1997). Based on 20 % oral bioavailability of nicotine (Hukkanen et al. 2005) and assuming linear kinetics, an oral dose of 60 mg would give rise to a plasma concentration of about 0.18 mg/L. The literature reports on fatal nicotine intoxications suggest that the lower limit of lethal nicotine blood concentrations is about 2 mg/L, corresponding to 4 mg/L plasma, a concentration that is around 20-fold higher than that caused by intake of 60 mg nicotine. Thus, a careful estimate suggests that the lower limit causing fatal outcomes is 0.5–1 g of ingested nicotine, corresponding to an oral LD50 of 6.5–13 mg/kg. This dose agrees well with nicotine toxicity in dogs, which exhibit responses to nicotine similar to humans (Matsushima et al. 1995). So, in reality the LD50 is much more likely to be an order of magnitude higher than the number you provided from Wikipedia. This however agrees with the former number you provided, and I guess this is the study where it came from.

ekianjo 8y ago

Wikipedia is not the place you should look for reliable toxicological information. There are better places online (and free of access, too). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880486/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880486/ > Although an LD50 of 0.8 mg/kg would implicate that the toxicity of nicotine is similar to or even higher than that of cyanide, fatal nicotine intoxications are relatively rare, and there are countless records of subjects who survived consumption of nicotine in amounts far higher than 60 mg (Larson et al. 1961). The most drastic example is probably survival of a suicide attempt with 4 g of pure nicotine (Schmidt 1931). While this is certainly an exceptional case, in which the amount of bioavailable nicotine was markedly reduced by vomiting, ingestion of tobacco or nicotine gums at doses up to 6 mg/kg nicotine was reported to evoke symptoms of intoxication without causing death (Malizia et al. 1983; Smolinske et al. 1988). These and many other literature reports on nonfatal nicotine intoxications are hardly compatible with a lethal dose of 60 mg or less. > Several detailed reviews are available on fatal nicotine intoxications caused by either suicidal intent or accidents, latter mainly resulting from misusage of nicotine-containing solutions marketed as pesticides (Esser and Kühn 1933; Larson et al. 1961; Maehly and Bonnichsen 1963; Tiess and Nagel 1966; Hayes 1982; Corkery et al. 2010; Solarino et al. 2010). The postmortem data reviewed by Maehly and Bonnichsen (1963) and more recently by Corkery et al. (2010) and Solarino et al. (2010) revealed minimal nicotine blood levels of 2 mg/L, but rapid decline of blood nicotine after death (Sanchez et al. 1996) may have led to underestimation of the actual lethal concentration in delayed autopsies. > Despite these uncertainties and the complex pharmacokinetics of nicotine (Hukkanen et al. 2005), a rough estimate of the amount of ingested nicotine from postmortem analyses of blood levels appears feasible. Smoking a cigarette results in uptake of approximately 2 mg of nicotine and gives rise to mean arterial plasma concentrations of about 0.03 mg/L (30 ng/ml) (Gourlay and Benowitz 1997). Based on 20 % oral bioavailability of nicotine (Hukkanen et al. 2005) and assuming linear kinetics, an oral dose of 60 mg would give rise to a plasma concentration of about 0.18 mg/L. The literature reports on fatal nicotine intoxications suggest that the lower limit of lethal nicotine blood concentrations is about 2 mg/L, corresponding to 4 mg/L plasma, a concentration that is around 20-fold higher than that caused by intake of 60 mg nicotine. Thus, a careful estimate suggests that the lower limit causing fatal outcomes is 0.5–1 g of ingested nicotine, corresponding to an oral LD50 of 6.5–13 mg/kg. This dose agrees well with nicotine toxicity in dogs, which exhibit responses to nicotine similar to humans (Matsushima et al. 1995). So, in reality the LD50 is much more likely to be an order of magnitude higher than the number you provided from Wikipedia. This however agrees with the former number you provided, and I guess this is the study where it came from.