“Cocktail effect” is greater than the sum of its parts

July 16, 2013

A knife on its own is nothing to worry about. The same goes for an electrical socket. But put them together and you’ve got trouble. Or consider bleach and ammonia. In limited quantities they can each be used safely but mix them and you’ve got a situation on your hands. Things that behave one way individually can be an entirely different matter when combined.

Recent studies have found that low-level exposures to mixtures of chemicals can have different, more dangerous health effects than exposure to any of the same chemicals individually, even at the same levels. This is sometimes referred to as the “cocktail effect”.

One UK study looked at five chemicals considered to be endocrine disruptors (i.e. hormone-affecting). These chemicals are present in everything from cosmetics to cleaning products, sofas to sunscreen, toys to toothpaste.

“An analysis of how five of the most widely used of these chemicals are controlled has found that regulators are putting human and environmental health at risk by being insufficiently vigilant. Experts warn that watchdogs are not considering the cumulative “cocktail effect” of multiple exposures to these substances, and have failed to keep up to date with the latest science.”

A 2012 survey from the Danish EPA found that daily life exposure to multiple potential endocrine disruptors from food, indoor environment and consumer products may cause a risk for some pregnant women and fetuses and further, that there is a need to reduce exposures of pregnant women to potential endocrine disruptors. The study concluded

“It appears to be of major importance that a cumulative risk assessment is performed instead of a risk assessment for each single substance.”

At The Institute of Environmental and Human Health at Texas Tech researchers found cancer risks doubled when two carcinogens were present at “safe” levels. Scientists generally test one chemical at a time on cells. However, Kamaleshwar Singh and doctoral student Justin Treas were interested in studying two chemicals at once. They found that co-exposure created a greater effect than single exposure.

“In the experiment, human prostate cells were treated about once a week for six months with arsenic, estrogen and a combination of the two. Many of the tests involved levels of arsenic, estrogen or both at levels considered safe by the Environmental Protection Agency.
Treas said the two chemicals stopped the MLH1 gene, which is responsible for sending the signal to start the self-destruct sequence when a cell is damaged. Because the self-destruct couldn’t activate, the cells became cancerous after exposure.”

As Client Earth stated in its response to the UK study,

“laws usually assess each exposure individually as opposed to in combination. In addition, the risks from chemicals, such as pesticides, biocides and industrial chemicals, are assessed separately under different pieces of legislation. In reality, people and wildlife are exposed to many different chemicals at the same time.”

What is needed is risk assessment based the reality of the world we live in, a world of multiple exposures.