The investigation by The Guardian and Quinto Elemento Lab begins in the US with discarded metal junk – such as cars and refrigerators. Steel plants vaporize it in “electric arc” furnaces to pull out the valuable steel. About 70% of American steel comes from this recycling process, according to the American Iron and Steel Institute.
Most of the contaminants in the scrap – such as plastic car components, paint, and machine parts – are pulverized to dust and trapped in the steel plants’ pollution filters.
This dust, known as electric arc furnace dust, contains zinc but also other heavy metals such as brain-damaging lead and cancer-causing arsenic. It is recognized as hazardous waste in many countries, and as such the US requires it to have special handling when companies are processing and disposing of it.
American steel plants ship this dust to a facility in the Monterrey area, in northern Mexico, owned by a company called Zinc Nacional.
It has been processing this waste since at least the 1990s. In 2022 alone, US companies sent nearly 200,000 tons of this dust to Zinc Nacional – the equivalent of more than 90,000 new cars.
The plant profits off the dust by putting it through high-heat furnaces to reclaim zinc, which is sold for use in products such as fertilizer, animal feed, and paint. A top company official says Zinc Nacional’s practices promote reuse by “transforming an industrial byproduct into valuable chemicals and finished products”.
But in the process, the plant releases lead, cadmium, arsenic, and other toxic substances into the atmosphere as fine dust, according to company emissions reports that are submitted to the Mexican government and were obtained by the Guardian and Quinto Elemento Lab.
Air emissions like these contribute to a huge air pollution problem in Monterrey, a metropolitan region and industrial hub of 5.3 million people.
Nearby residents complain that the plant is polluting their neighborhood with dust and smoke, and they allege it produces acid rain that destroys the paint finish on their cars.
Soto Jiménez tested 18 sites within a 2.5km (1.5 mile) radius of the plant.
They included homes, schools, and streets. Several samples were taken from each site, including outdoor and, where possible, indoor samples.
Experts say the results are extremely concerning. After reviewing them, an official from Mexico’s top environmental regulator, known by its acronym Semarnat, said it would seek an investigation to “learn in-depth about the company’s compliance” with environmental regulation.
At most sites, lead levels in the outdoor dust and soil were higher than what the US Environmental Protection Agency considers a potential health risk for humans.
Three sites had outdoor lead levels five to six times greater than the US health risk threshold.
Lead wipe tests, which measured lead on indoor window sills, indicated levels that were higher than the US threshold at all locations where Soto Jiménez could collect samples.
One primary school had levels 1,760 times greater than the US threshold, and three homes had more than 400 times what the US considers a potential risk.
Cadmium, which can damage the lungs and kidneys, exceeded the US threshold at at least 14 out of 18 test sites.
And arsenic, which can cause cancer, exceeded the US threshold at every test site. Levels at many test sites also violated Mexican pollution standards, even though they are more lenient than those in the US.
Ultimately, nearly every site had concerning levels of several contaminants, according to these tests.
This raises the question of why US companies are sending hazardous waste to Mexico in the first place, and whether the country is equipped to handle it.
The steel dust that arrives here is part of a little-known and much larger trade in hazardous waste, the Guardian and Quinto Elemento Lab have found. In 2022, the most recent year for which data is available, US companies shipped 1.4m tons of their hazardous waste to Mexico, Canada, and South Korea – ranging from old lead car batteries to industrial solvents and toxic sludge from factories.
The Monterrey region received nearly half of all hazardous waste the US exported in 2022, including not only steel dust but hundreds of thousands of tons of lead batteries.
And nearly one-seventh of the waste the US exported globally in 2022 was the contaminated steel dust that ended up at Zinc Nacional, in the Monterrey-area municipality of San Nicolás de los Garza.
Click here to read the complete, original article by Verónica García de León in Quinto Elemento Lab.
Source: Quinto Elemento Lab
