Toxic plastic additives that we ingest through food

The use of plastic materials in food production and distribution has contributed to improved hygiene during preservation, storage, and transportation, preventing the spread of fungi, viruses, and bacteria that could reach consumers. However, this has resulted in the exposure of products to these petroleum-derived polymeric materials, the long-term effects of which could be harmful to health.

Plastics are made up of a series of chemical additives that improve their mechanical and physicochemical properties, such as elasticity, strength, and durability. The list of these additives is long, with the most abundant being plasticizers, among which are organophosphate esters (OPE) and phthalates (PAE).

Both groups of compounds show evidence of long-term toxicity to human health, primarily due to their involvement in potential metabolic alterations and reproductive effects. Therefore, there is a growing trend among manufacturers to use alternative plasticizers that, a priori, do not present harmful effects.

These alternatives include citrates such as acetyl tributyl citrate (ATBC) and adipates such as di-2-ethylhexyl adipate (DEHA). However, studies have already concluded that these two compounds are not as harmless.

Human exposure to these plasticizers can occur through various routes, such as inhalation of airborne particles, ingestion of dust, or dermal contact. However, the primary route is the ingestion of food and beverages . These may be contaminated due to the presence of plasticizers in the environment, but they can also become contaminated during production and processing, and, of course, through the type of packaging.

Since the presence of plasticizers in foods is circumstantial, they are not considered food additives, and therefore, there is no legislation regulating maximum residue levels, as is the case with other contaminants such as pesticides or antibiotics.

In a study recently published in the Journal of Hazardous Materials, we evaluated the presence of plasticizers in foods sold in Spain . The sampling was based on consumption data from the Ministry of Agriculture, Fisheries, and Food.

The samples were classified as infant foods (powdered milk, yogurt, cereals, fruit, meat, and fish purees), cereals and legumes and sweets, condiments, dairy products and eggs, fish products, fruits and vegetables, and meat and oils. To maximize variability, the selection was random, alternating between different brands and establishments.

We analyzed 109 samples, and detected at least one plasticizer in 85% . The alternative plasticizers ATBC and DEHA were the most common compounds. It's worth noting that they were also detected in foods packaged in glass.

Compounds such as ATBC are suitable for use in polymer resins designed to prevent contact between the metal lid and the food. Regarding DEHA, the highest levels were found in products sold in bulk, as these are wrapped in transparent plastic film.

These results show that purchasing food at food markets does not necessarily imply lower exposure to plasticizers than purchasing food in vacuum-packed plastic trays.

Cooking is another factor to consider. According to data from the Ministry of Agriculture, 5.1% of the population chooses to use the microwave for ready-to-cook foods, including vegetables such as potatoes or broccoli. Furthermore, more than 10% of food preparations are done in the oven, with an increasing trend in the use of bags that allow steam cooking, reducing preparation time and avoiding the use of frying oils.

The study shows that cooking using these methods can increase exposure to plasticizers up to 50 times . Although the levels of migration from packaging to food are within the limits established by the European Commission's regulations, it is recommended not to cook food in these types of plastic containers.

The results obtained allow an estimate of the daily dietary intake of plasticizers. This estimate was made for the adult population (over 18 years of age) and for the child population, given that lower body weight implies greater exposure, distinguishing between infants under 12 months of age and children between 1 and 3 years of age. Furthermore, two exposure scenarios were considered: "normal," based on median values, and "high exposure," based on the 5% most contaminated samples.

Organizations such as the European Food Safety Authority (EFSA) and the United States Environmental Protection Agency (EPA) have assigned maximum safe daily intake values ​​for some of the compounds analyzed.

Considering the normal scenario, the samples analyzed did not exceed the recommended values ​​in any case. However, considering the high-exposure scenario for infants and children, safe values ​​are exceeded for two compounds: the phthalate DEHP and the organophosphate EHDPP . For three other compounds, the values ​​would be only 10 times below the risk threshold—keep in mind that when carcinogenic risk values ​​are established, for example, a value that is a million times lower is considered a precaution.

It should be noted that dietary intake is only one of the possible routes of exposure to these toxins, in addition to exposure through inhalation, ingestion of dust, and dermal contact. The sum of all these exposures could lead to higher daily doses and exceed safe levels for a greater number of toxic compounds.

These findings clearly show that dietary exposure to plasticizers is a risk factor. Although current legislation is being enforced, more stringent regulations are needed, at least for those compounds whose harmful effects are already known.

In Spain, the waste law passed in 2022 banned the use of phthalates in packaging. However, we do not know if there are any controls in place to enforce it . The competent authorities must establish controls on the marketing of plastic materials to ensure the absence of the regulated compounds.

Furthermore, it would be important for the directives to be more ambitious and include other compounds that are now known to be toxic. And we must not forget the need to apply the precautionary principle to new plasticizers that appear to be safer alternatives, but are not always so.

This article was originally published on The Conversation .