Potency

• Simple Definition
• Advanced Definition
• Expanded Definition

Simple Definition

Relative potency is a way of comparing the ‘strength’ of two chemicals in regard to their ability to produce an adverse health effect. A simple analogy is the degree of burning sensation in the mouth that comes from eating various types of hot peppers. Some types (e.g., jalapeño and Habaneros) produce a more potent response than others (e.g., hot wax peppers).

Advanced Definition

Potency is the expression of relative toxicity of an agent as compared to a given or implied standard or reference. Relative potency is a way of comparing the ‘strength’ of two chemicals in regard to their ability to produce an adverse health effect. It shows that ingesting equal amounts of substances with different potencies will produce different severity of effects. A simple analogy is the degree of burning sensation in the mouth that comes from eating various types of hot peppers. Some types (e.g., jalapeño and Habaneros) produce a more potent response than others (e.g., hot wax peppers).

Expanded Definition

Potency is the expression of relative toxicity of an agent as compared to a given or implied standard or reference. Relative potency is a way of comparing the ‘strength’ of two chemicals in regard to their ability to produce an adverse health effect. It shows that ingesting equal amounts of substances with different potencies will produce different severity of effects. A simple analogy is the degree of burning sensation in the mouth that comes from eating various types of hot peppers. Some types (e.g., jalapeño and Habaneros) produce a more potent response than others (e.g., hot wax peppers).

Potency is a very important consideration when discussing potential endocrine disruptors. Probably the most common true artificial endocrine disruptors are the contraceptive pill and hormonal therapies, both of which are readily ingested as a lifestyle choice or for their therapeutic benefits. Even these substances are actually much less potent than naturally occurring estrogens to which the human body is continually exposed, so they generally need to be given in high doses in order to achieve their intended effects.

As an example of relative strength, or potency, the ultra violet light filter benzophenone-3 (used in some sunscreen formulations), which has been alleged to be an endocrine disruptor, is 1.5 million times less potent in its estrogenic effect than ethinylestradiol, which is the active ingredient used in oral contraceptives (i.e., birth control pill). Looking at this in another way, if aspirin were 1.5 million times lower in potency, you would need to consume more than thirteen times your body weight of pure aspirin at one time just to cure a headache. Clearly, that is not possible. In exactly the same way, most endocrine disruptors are simply too weak to have any disrupting effect at the quantities to which most people are exposed.

Many so-called ‘endocrine disruptors’ (more accurately, endocrine mimics) are abundant in nature. We ingest them in the food we eat in concentrations many million times greater than in the other exposure scenarios that may be encountered, such as their use in cosmetics, personal care, and home care products. Endocrine mimics include phytoestrogens – estrogen-like compounds found naturally in plants. We eat these in foods such as cabbage, soya beans and sprouts. No adverse health effects have been associated with these dietary exposures.