Cocktail effect makes chemicals more toxic

The knowledge we have about the effects of various chemicals is based on studies of one chemical at a time. Mixing different chemicals might alter their effect. This is commonly known as the cocktail effect and is the subject of increasing discussion among researchers.

Cleaning supplies

This may partly be due to different chemicals having either the same or the opposite effect, which then strengthens or weakens the other's effect, and partly due to a chemical being able to influence how another chemical is absorbed, spread or eliminated in the body. It may result in negative effects being added so that 1+1=2, but it can also be amplified even more so that 1+1=3 or greater.

Doses previously considered safe suddenly become unsafe. For example, it has been shown that mixtures of low levels of environmental toxins in fish can double the toxic effect on human cells compared with the effects of those chemicals separately, that is, 1+1=4.

Toxicological timeline

1500s: Swiss physician Paracelsus coins "the dose makes the poison".

1775: Increased incidence of testicular cancer in chimney sweeps is discovered.

1929: Polychlorinated biphenyls, PCBs, are introduced by chemical, pharmaceutical and agricultural companies.

1942: Dichlorodiphenyltrichloroethane, DDT, begins to be used as a pesticide.

1961: The thalidomide disaster - drugs for pregnant women cause birth defects.

1970s: Attention is drawn to the health and safety risks of chemicals in the workplace. DDT and PCBs are banned after the discovery of harmful effects in nature.

1980s: Attention is drawn to chemicals that cause cancer.

1990s: Attention is drawn to endocrine disruptors and fetal sensitivity to chemicals.

1990s and 2000s: Attention is drawn to the toxicity of acrylamide - the Hallandsås Tunnel (sealant) in 1997, foods (French fries and crisp bread) in 2002

2001: Attention is drawn to the cocktail effect – can 1 + 1=3?

2007: In January, the EU bans endocrine-disrupting phthalates in plastic toys and childcare products. In June, the European chemical legislation (REACH) is introduced throughout the EU to tighten corporate responsibility.

2008: Increasing use of nanoparticles and nanomaterials – potential health risks begin to be discussed.

2011: The EU bans baby bottles made of polycarbonates, which leach bisphenol A.

2013: In March, the European Parliament decides that the European Commission shall put forward proposals by June 2015 on the management of endocrine disruptors in consumer products. In July, the Swedish governments ban on substances containing bisphenol A in packaging for foods for children under the age of three enters into force.

Text: Fredrik Hedlund. First published in Swedish in Medicinsk Vetenskap 2/2013.