posted on 2012-09-04, 00:00authored byQiao-Guo Tan, Wen-Xiong Wang
Relating the toxicity of metals to their internal concentration
is difficult due to complicated detoxification processes within organisms.
Only the metabolically available metals are potentially toxic to organisms,
while metals in the detoxified form are toxicologically irrelevant.
Accordingly, we developed a two-compartment toxicokinetic–toxicodynamic
model for metals in a freshwater cladoceran, Daphnia magna. The toxicokinetics simulated the bioaccumulation processes, while
the toxicodynamics quantitatively described the corresponding processes
of toxicity development. Model parameters were estimated for D. magna and three metals, i.e., cadmium, zinc, and mercury,
by fitting the literature data on metal bioaccumulation and toxicity.
A range of crucial information for toxicity prediction can be readily
derived from the model, including detoxification rate, no-effect concentration,
threshold influx rate for toxicity, and maximum duration without toxicity.
This process-based model is flexible and can help improve ecological
risk assessments for metals.