Food and diet

Pizza boxes under scrutiny

“Takeaway pizza may be bad for your health because of the boxes they’re delivered in”, the Daily Express reported today. It said that boxes made from recycled material could contain toxic inks, glues and dyes. When hot pizza is put in the boxes, temperatures can reach 60-65C, increasing the chances of toxic substances migrating from the packaging to the food. The report said that scientists at the University of Milan examined 16 pizza takeaways and their cartons, and found varying levels of one chemical of particular concern, diisobutyl phthalate (DIBP).

In this small laboratory study, the researchers developed a method to determine the amount of DIBP in the gas inside pizza boxes at high temperatures. The direct applicability of this to pizzas in real-life is not clear. It also is not clear if exposure to the levels of DIBP seen in this study has any effects on human health, and if it represents a real threat. More research is needed, and the hope is that a study such as this will prompt more research by regulators into the effects of this particular phthalate.

Where did the story come from?

Dr Monica Bononi and Fernando Tateo from the University of Milan carried out the study. There is no indication of who funded the research. The study was published in the journal Packaging Technology and Science.

What kind of scientific study was this?

In this laboratory study, the researchers explored the implications of using recycled paper and cardboard in the production of pizza boxes. The recycled paper and cardboard can come from a variety of sources (not just other food cartons), and can contain substances that food should not be exposed to because they may carry health risks if eaten. In Italy, the use of recycled paper in pizza boxes is banned; however, the authors state that there is ‘frequent failure to comply with this law’.

The researchers were particularly interested in quantifying the amount of diisobutyl phthalate (DIBP) that takeaway pizzas are exposed to. DIBP is used in inks, laminates and adhesives, and under Italian law is prohibited in the manufacture of paper-based materials that come into contact with food.

The researchers collected 16 samples of takeaway pizza boxes from 16 different pizzerias in northern Italy in 2006. They cut 8cm-diameter discs from the pizza boxes and exposed them in sealed containers to temperatures of 60C. A fibre was then suspended in the container for 60 minutes to determine the concentration of DIBP in the gas that collected. The measurements were repeated with all 16 pizza box samples. Based on their measurements, the researchers calculated an ‘exposure index’, which represented the DIBP exposure, taking into account the entire internal surface area of the pizza box.

What were the results of the study?

The researchers said there was “very large range of DIBP released in the 16 sampled pizza boxes, ranging between the exposure indices of 6 and 72 [microgrammes]’. They say that the method they have developed is a good way of assessing exposure to DIBP.

What interpretations did the researchers draw from these results?

The researchers concluded that they used analytical methods to identify the contaminant DIBP in take away boxes. By applying standardized methods in the 'calculation of an exposure index for DIBP in take away boxes' they provide an approach to calculate the potential risk of contamination by this phthalate for a box of a given area.

They also say that their findings show that many pizza boxes in Italy contain recycled paper, which is contrary to Italian law.

What does the NHS Knowledge Service make of this study?

This small laboratory study primarily offers the packaging industry a good method for testing the amount of DIBP emanating from recycled cardboard and paper. There are several important factors that should be considered when interpreting the results:

  • Samples of the substance in the gas around the box samples were collected using a fibre exposed for 60 minutes at 60 degrees centigrade. In real life, pizzas are unlikely to be exposed for this long and at such a constant temperature because they begin to cool after some time. What effect this will have on the pizzas’ absorption of DIBP is unclear.
  • Importantly, the effects of exposure to DIBP and other phthalates on human health are not clear. More research is needed to determine if DIBP has any negative health effects, and if the levels occurring in pizza boxes represent a substantial exposure.
  • The study was carried out in Italy on Italian pizza boxes. It is not clear how applicable these findings are to the UK and whether UK pizza boxes also contain DIBP.

Until more research is carried out on the effects of DIBP on human health, it is premature to be overly concerned about the effects of exposure in this way. The findings of this study should prompt further research. Because of the potential hazards of phthalates, the European Commission’s Scientific Committee on Food has set some limits for their use, and these apply to the UK.

Sir Muir Gray adds...

Good point, but the main health challenge is the big pizza not the big box.

NHS Attribution