Findings from a Spanish study have demonstrated that carcinogenic environmental pollutants present in raw or unprocessed meat can only be reduced by cooking processes that remove fat from the meat.
Its significance places meat-processing techniques such as salting, fermentation, curing, and smoking under the spotlight again.
Last year the International Agency for Research on Cancer (IARC) concluded that the consumption of red and processed meat was linked to an increased risk of cancer.
According to the study published in The Lancet Oncology, the carcinogenic substances could be generated by the meat-processing techniques as well as heating the meat to high temperatures.
This would release substances assumed to be carcinogenic such as nitrous compounds, polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatic amines, among others.
The study involved scientists from the Rovira i Virgili University (URV) located in the Catalonia region of Spain.
They collated results from an initial survey (BF1) that was performed between 2000 and 2002. Here contaminant concentrations of arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) were determined, among other contaminants.
This was then followed up with a second survey in 2006-2008 with a third and final survey carried out in 2008.
The study’s primary finding centred on the contaminant concentrations in the meat along with inorganic and organic environmental pollutants, many of them persistent organic pollutants (POPs).
Most of these substances are fat-soluble, so food with high fat content would accumulate higher levels of micro pollutants than plant matter.
"PCBs and other POPs accumulate in the fatty parts of meat because they are fat soluble. Reduced consumption of meat fats will reduce the intake of PCBs,” commented Dr José Luis Domingo, lead author of the work at the laboratory of Toxicology and Environmental Health at the URV.
“On the other hand, eating meat with a high fat content can result in a significant exposure to PCBs," he added.
The scientists then looked into how various cooking processes, such as frying, grilling, roasting or boiling, affected the presence of pollutants in meat.
Results indicated that different cooking types influenced the concentration of toxins differently depending on the meat product.
POPs exhibited very little change in cooked and raw meat. As they are organic substances, the researchers argued that only cooking processes that release or eliminate fat from meat would tend to reduce the total concentration of these pollutants in the cooked meat.
The study recommended the reduction of either meat consumption or meat-derived fat as actions to reduce contaminant exposure.
"This would prevent not only cardiovascular risks, but also carcinogens, especially those associated with exposure to some environmental pollutants in the meat," they stated.
The researchers also pointed out that the concentrations of hazardous substances were also dependent on the original content of toxins in the food before cooking. They cited animal rearing techniques and environmental factors as big influences in determining contaminant concentrations.
“Overall, the level of contamination in raw and unprocessed meat is below that of fish and seafood, although it is much higher than that of fruits, vegetables and legumes," said Domingo.
Source: Environmental Research
Published online ahead of print, doi:10.1016/j.envres.2015.11.031
“Carcinogenicity of consumption of red and processed meat: What about environmental contaminants?”
Authors: José L. Domingo, Martí Nadal