Human exposure to trace elements and PCDD/Fs around a hazardous waste landfill in Catalonia (Spain)

Our plain-English summary of Human exposure to trace elements and PCDD/Fs around a hazardous waste landfill in Catalonia (Spain), by M. Herrero, J. Rovira, M. Marquès, et al (The Science of the Total Environment, 2020).

The study

• Authors: M. Herrero, J. Rovira, M. Marquès, M. Nadal, J.L. Domingo
• Journal: The Science of the Total Environment
• Published: 2020;710:136313
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Hazardous waste landfills (HWLs) usually mean the end of non-reusable, non-recyclable and non-recoverable wastes derived from industrial activities. A number of hazardous compounds and toxic elements, such as PCDD/Fs, Cd, Cr, Hg, Pb and As, is associated to these wastes. The HWL of Castellolí (Catalonia, Spain) treats a variety of hazardous wastes, which include bottom ashes from waste incinerators and asbestos potentially containing those toxicants. In 2007, our group began a surveillance program inside the HWL and in nearby villages focused on assessing the environmental levels of PCDD/Fs and toxic elements. Here we summarize the most updated results, corresponding to data from samples collected between 2015 and 2018. The levels of most trace elements (As, Cd, Cr, Ni and Pb) in soils, as well as those of Cd and Pb in air, were significantly higher (p < 0.01) inside the HWL than outside. However, no relevant differences were noted in the concentrations of trace elements when comparing the results of villages near the HWL with those located farther. With respect to PCDD/Fs, a progressive decrease was observed between the first (2007) and most recent (2018) surveys. The human health risks associated with the exposure to trace elements and PCDD/Fs exposure were within acceptable ranges according to national and international legislations (HQ < 1 and Cancer risk < 10-5).

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In plain English

This study monitored pollution and health risks around a hazardous waste landfill in Castellolí, Spain. It accepts asbestos among other wastes, but asbestos was not measured. Air was sampled in 2015 to 2018 and soil in 2016 and 2018, inside the landfill and in four towns 2.5 to 14 km away (Copons: soil only). PCDD/Fs (dioxins and furans) and arsenic, cadmium, chromium, mercury, nickel and lead were measured and compared with surveys since 2007. From 2007 to 2018, soil levels of most elements were significantly higher inside the landfill than outside. In 2015 to 2018, nearby towns did not differ significantly from control towns; over 2007 to 2018, airborne chromium was significantly lower nearby. Soil dioxins inside the landfill fell over time. Non-cancer hazard quotients were below 1 everywhere. Inside the landfill, chromium(VI) cancer risk, calculated assuming chromium(VI) was one sixth of total chromium, exceeded the Spanish limit of 10 to the minus 5; international standards accept up to 10 to the minus 4. The authors concluded the landfill is not an important emission source for surrounding areas.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Environmental surveillance (monitoring) study of air and soil, with a modelled human health risk assessment; part of a program running since 2007
• Who was studied: Sampling sites, not people. There were two points inside the Castellolí hazardous waste landfill (Catalonia, NE Spain) and four outside it. The outside sites were the towns of Castellolí (2.5 km) and Òdena (3 km), considered potentially affected, and Jorba (11 km) and Copons (14 km), considered background/control. Air was sampled each July from 2015 to 2018, but not at Copons. Soil was sampled in 2016 and 2018. Results were compared with campaigns from 2007 onward.
• Exposure: Environmental levels of PCDD/Fs (dioxins and furans), arsenic and five heavy metals (cadmium, chromium, mercury, lead, nickel) in soil and in airborne PM10. Exposure was estimated through soil and dust ingestion, skin contact and inhalation. The landfill receives asbestos among other wastes, but asbestos was not measured.
• Main results:
  • Across all campaigns from 2007 to 2018, soil levels of arsenic, cadmium, chromium, nickel and lead were significantly higher (p less than 0.01) inside the landfill than at sites outside it.
  • In soils sampled in 2016 and 2018 (the 2015 to 2018 period), there were no significant differences between the potentially affected towns (Castellolí, Òdena) and the unaffected towns (Jorba, Copons).
  • In air from 2015 to 2018, there were no significant differences in metal levels between affected sites (Castellolí, Òdena) and the unaffected site (Jorba) outside the landfill.
  • In air over 2007 to 2018, cadmium and lead were significantly higher (p less than 0.01) inside the landfill than outside it.
  • Over 2007 to 2018, the mean airborne chromium level in the affected area (0.389 ng/m3) was significantly lower (p less than 0.05) than in the unaffected area (2.26 ng/m3).
  • Over 2007 to 2018, mean total soil PCDD/F levels were 5.03 ng WHO-TEQ/kg inside the landfill. They were 0.23 ng WHO-TEQ/kg in the affected area and 0.18 ng WHO-TEQ/kg in the unaffected area.
  • Inside the landfill, soil PCDD/F levels in 2016 and 2018 were significantly lower (p less than 0.05) than in the 2007 baseline survey.
  • Air PCDD/Fs in Castellolí town fell from 371 fg WHO-TEQ/m3 in 2007 to 2 fg WHO-TEQ/m3 in 2018.
  • For air PCDD/Fs from 2015 to 2018, there were no significant differences between campaigns, or between samples taken inside and outside the landfill.
  • In soil, lead inside the landfill in 2018 (64.4 mg/kg) was the only value exceeding the most restrictive Catalan reference level (60 mg/kg). It did not exceed the industrial-soil limit of 550 mg/kg.
  • Non-cancer hazard quotients were below the threshold of 1 at all sampling points and in all campaigns. The highest, around 0.2, were found inside the landfill.
  • Only chromium(VI) inside the landfill exceeded the maximum acceptable cancer risk of 10 to the power of minus 5 under Spanish legislation. This calculation assumed chromium(VI) was one sixth of total chromium. The authors noted that international standards consider values between 10 to the minus 6 and 10 to the minus 4 acceptable.
• The authors' conclusion: The authors concluded that, although levels were higher inside the landfill, it is not an important source of trace element and PCDD/F emissions for surrounding areas. They also concluded that health risks for nearby residents are below national and international thresholds, and that biomonitoring of residents would be valuable.
• Limitations the authors state:
  • Limited spatial and temporal resolution; more sampling points would clarify the landfill's influence.
  • Short sampling times (24 h for trace elements, 48 h for PCDD/Fs) limited the ability to identify other emission sources such as traffic or agricultural burning.
  • Air results are daily values, not the annual averages that EU limits refer to.
  • Risk calculations assumed chromium(VI) was one sixth of total chromium and that all arsenic was inorganic.
  • No biomonitoring of residents was done; the authors say parallel biomonitoring would complement the program.

Related studies

• Leaching behaviour of hazardous demolition waste — N. Roussat, J. Méhu, et al. (2008)
• Health effects of hazardous waste — S.M. Dearwent, M.M. Mumtaz, et al. (2006)
• Trace elements in hazardous mineral fibres — A. Bloise, D. Barca, et al. (2016)
• Health effects of natural dust: role of trace elements and compounds — A.G. Cook, P. Weinstein, et al. (2005)
• Major and trace element compositions of the UICC standard asbestos samples — D.R. Bowes, C.M. Farrow (1997)
• The export of hazardous industries in 2015 — B. Castleman (2016)

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