540
Cercarial encystment at concentrations of 25000 microg/l or higher was significantly impaired by all test metals; however, at lower concentrations only zinc demonstrated toxicity.
 adverse event: demonstrated 
Please tell me event type and its trigger word from given type options. Output format is "type: trigger".  Option: adverse event, potential therapeutic event 
Text: {0} 
Answer:
 adverse event: demonstrated 