Toxicity of aliphatic amines to barnacle larvae

Abstract

1. 1. Nauplius larvae of the barnacle Elminius modestus Darwin were used to assess the toxicities of some primary, secondary and tertiary aliphatic amines and quaternary compounds. 2. 2. For the three series of aliphatic amines toxicity was largely determined by the concentration of the uncharged amine species 3. 3. With the exception of n-heptylamine, which is markedly time-dependent, studies on the time-dependence of toxic action indicated that the aliphatic amines occupied an intermediate position between chemically toxic agents (e.g. cupric ion) and typical physical narcotics such as amyl alcohol. 4. 4. At 30°C the ld 50 values for n-amylamine and n-decylamine were approximately half those obtained at 6°C. Over this same temperature range mercuric chloride showed a tenfold decrease in ld 50. 5. 5. Determinations of thermodynamic activity coefficients allowed evaluation of the thermodynamic activity at which the uncharged amine species exerts its physiological action. Where toxicity is largely determined by the concentration of this species the amines act at thermodynamic activities between 10 −3 and 10 −6, the primary amines being the most toxic. It is argued that the amines qualify as anomalous members of the group of physically toxic substances.