Usually, binding of autoinducers to receptors does not occur until a threshold concentration of autoinducers is achieved.

At a threshold concentration, LasR binds N-(3-oxododecanoyl)-homoserine lactone.

The result of these lethal pharmaceutical concentrations in fish is that renal lesions and damage to the gills are due to a threshold concentration of 5 g/L.

In insulin resistant tissues, a threshold concentration of insulin is reached causing the cells to uptake glucose and therefore decreases blood glucose levels.

The threshold concentration for this action to occur is 5 ng/ml (5 parts per billion) with 50% of cells rounded at 50 ng/ml.

Odors have a threshold concentration, which is usually low for several reasons: cost, size of the unit, toxicology and/or allergic reactions, etc.

And maybe that threshold concentration is enough to harm fish.

The compound responsible is 2-ethoxyhexa-3,5-diene, which has a low sensory threshold concentration of 1 ng/L.

The threshold permissible concentration is 148 Bq/m.

The paper concludes by showing that the model predicts that there are a few threshold concentrations that cause interesting effects on the activity of the cell.