How much contamination do you eat?

How much contamination do you eat?

All our actions and decisions have consequences in our environment. What we wear, where we go, how we move or what we eat has a direct impact not only on our lives, but also on the environment. It is well known that the meat we consume generates a great ecological impact in terms of CO₂ emissions, but how much does it pollute, for example, a plate of spaghetti Bolognese or some macaroni and cheese?

A team of researchers from the University of Oxford studied the environmental impact of more than 57,000 food products sold in supermarkets. The study, published at the beginning of August in the scientific journal PNAS, takes into account the impacts on CO₂ emissions of the ingredients that make up the products. It does this by using the environmental footprints of raw materials and the ingredient lists of specific products to calculate the total footprint of each product. For example, calculating the impact of “spaghetti bolognese” would combine the impacts of the ingredients (pasta, ground beef, sauce, and any additional ingredients) in their weighted proportions.

To develop this analysis, the researchers used data from the largest meta-analysis of food system impact studies to date (Poore & Nemecek, 2018). This analyzes a set of data taken from around 38,700 commercially viable farms in 119 countries and 40 products that represent 90% of the world’s consumption of protein and calories. From there, data on land use, greenhouse gas emissions, eutrophication emissions, freshwater withdrawals, and scarcity-weighted water are extracted.

Let’s take, as an example, a possible daily menu of a person, with the portions recommended by the Ministry of Health to maintain a healthy diet. For breakfast, cereals (40 grams recommended) with —cow’s— milk (250 ml); mid-morning, an apple (150 g); for lunch, a plate of macaroni and cheese (100 g), a beef burger (125 g) with lettuce (100 g) and for dessert, a pear (150 g). For dinner, bearing in mind that there is no afternoon snack, a Caesar salad (250 g), some pineapple chunks (150 g) and a yogurt (250 g). In addition, during the day, we have had three coffees —decaffeinated or not, it doesn’t matter— capsules (7 grams of coffee each). According to the study published in August, during this day our diet would have caused the emission of 11.6 kilos of CO₂ into the atmosphere.

If we compare it with the emissions of an average gasoline-powered car —taking into account that, according to data from the European Environment Agency, a medium-sized gasoline car emits on average about 0.143 kg of CO₂ every kilometer—, we would be producing the same amount of carbon dioxide that this car would generate in 81 kilometres, the same distance as from Barcelona to Tarragona or from Madrid to Ávila.

Meat products are, for the most part, the ones that emit the most kilos of CO₂ —in their production and processing—. One kilo of beef fillet, for example, generates is responsible for the emission of 129.75 kilos of carbon dioxide. The meatballs (in the same proportion) emit more than 95 kilos of CO₂; while the beef burgers, about 54 kilos.

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Among the ten foods that emit the most CO₂, 80% are meat products. Only two of them are not: instant coffee (28.78 kilos per kilo of product) and cottage cheese (25.28 kilos). The aforementioned spaghetti, if they did not have any dressing, would be responsible for the emission of 1.65 kilos of CO₂ into the atmosphere; while with Bolognese sauce, taking into account the proportion of tomato sauce and meat that accompany them, the impact rises to 7.83 kilos per kilo of product.

Fruits, vegetables, vegetables or vegetarian and vegan products are those that occupy the lower part of the table of polluting gas emissions. Not only do they allow for healthier diets and their intake is recommended daily, but their ecological footprint is smaller.

Other environmental impacts

Meat products are the ones that require the most land area for their production

The study not only analyzes the environmental impact according to the volume of CO₂ emitted, but also studies, among other variables, the square meters of land required to produce a kilo of said food or the amount of fresh water required for the same goal.

In the case of land area, beef derivatives are, by far, the ones that require the most square meters: a kilo of beef fillet is obtained thanks to the exploitation of 427.33 m² of land; one for minced meat, about 300 m²; one of meatballs, 215 m²; and beef burgers, more than 135 m². Dark chocolate is strained in fifth place, preceding several derivatives of lamb —such as leg of lamb, hamburgers, chops or stew—: for the production of a kilo of this sweet carbohydrate, about 50 square meters of land are needed, little less than a third of what is needed to produce a kilo of beef patties.

As far as necessary liters of water are concerned, meat products are relegated by nuts and their derivatives. Almond butter and almonds themselves are, with more than 6,800 and 6,400 liters respectively, the products that require the most water. Among the products that require between 3,000 and 4,000 liters are various types of nuts, oily fish — mackerel or tuna — and, among others, beef burgers. Water is not so predominant in the production of meat products, although most of its derivatives require more than 1,000 liters to produce a kilo of product.