Coffee and chemical contamination

"Espresso" machine coffee pods and capsules do not increase exposure to chemical contaminants

Over the last several years, various espresso-type machines have become available in France and can now be found in many households. ANSES, in a partnership with the French National Consumers Institute (INC), has launched a study to compare the levels of various chemical contaminants in coffee prepared using these machines with those of traditional drip brew coffee. The study shows that these new techniques do not modify the conclusions of previous risk assessments on consumer exposure to chemical contaminants.

New coffee-drinking habits

Coffee is the second most widely consumed beverage in France, after water and has therefore already been analysed in the context of the French Total Diet Studies (TDSs). Over the last several years, a wide range of espresso-type machines have appeared on the French market. Geared to home use, these machines can now be found in many households. This new way of drinking coffee has brought up a number of issues, especially on the possible chemical contamination of coffee through contact with the capsules or pods containing it. ANSES has therefore studied the consequences of using these new machines with regard to possible consumer exposure to certain chemical contaminants. It has also used this study, conducted in the context of a research and development contract (CRD) in partnership with the French National Consumers Institute (INC), to acquire data on the caffeine levels found in this type of coffee.

How did ANSES proceed?

This study made it possible to determine the levels of various chemical compounds in coffee made using these machines, in order to compare them with the levels already obtained in studies on traditional drip brew coffee (in the context of TDS2). 

The tests examined ten brands of capsules, representative of the market offer and compatible with one of the four most popular "espresso" coffee machine technologies sold in France. The various materials in contact with the ground coffee (capsule body and lid) were characterised in order to identify the specific substances to look for. In addition, the chemical substances which coffee may contain - mainly metals - were also examined.

The levels of the organic and inorganic contaminants which may be found in the coffee, the coffee-brewing process and the coffee-packaging materials were quantified for each prepared coffee using a variety of techniques. The concentrations measured were then compared to those found in drip brew coffee.

Analysis of diverse chemical contaminants: virtually identical levels

The average levels of all the chemical contaminants screened for except aluminium (cobalt, chrome, tin, nickel, copper, zinc and acrylamide) were slightly higher in the coffee solutions made with capsules than in the control coffee (drip brew coffee), but were of the same order of magnitude. These variations do not however significantly modify the contribution of coffee to consumer exposure to these chemical compounds, or to any risk that might be linked to them.

In addition, no organic compounds belonging to the phthalate or bisphenol A groups were detected. Although a substance known as furan was detected in all the samples, no conclusions could be made regarding it due to the physico-chemical specificities of this compound (in particular its extremely high volatility). ANSES is currently working on methodological developments which will enable more precise characterisation of furan.

With regard to caffeine, coffees prepared using the espresso coffee machines contained higher average concentrations of this substance than drip brew coffee. In addition, caffeine levels are higher in espresso obtained from capsules than in espresso obtained from pods. 

No effect on exposure to contaminants, but caffeine should be monitored

The study conducted by ANSES has therefore shown that the contaminant levels measured in the coffee from espresso-type machines are of the same order of magnitude as those measured in drip brew coffee and which were published by ANSES in its most recent Total Diet Study (TDS2) in 2011. The results of these analyses show that these new techniques do not substantially modify the conclusions of previous risk assessments on coffee-based consumer exposure to chemical contaminants. However these new machines could have repercussions on consumer exposure to caffeine if consumers drink the same amount of coffee made with them as traditionally-brewed coffee.