Toxicology and epidemiology experts have warned that thousands of people around the former UPL chemicals warehouse in Durban face two to three times the risk of developing heart and lung diseases (including lung cancer) after breathing in a cocktail of poisonous chemical fumes during the July riots more than two years ago.
This was only one of several alarming conclusions of a human health risk assessment that surfaced after the warehouse was set ablaze on 12 July 2021, and then burnt or smouldered for at least nine days before finally being extinguished, writes Tony Carnie in Daily Maverick.
The study – by experts from the Witwatersrand and North West universities, and Durban’s Apex Environmental occupational health consultancy – also recommends the Mumbai-based UPL agrochemicals firm should commission comprehensive human sampling checks and long-term health studies.
The new health surveillance scheme – including biological samples, urine and other pesticide-marker tests – should investigate whether the worst-exposed communities face a range of other potential health risks ranging from respiratory and skin problems to heart, kidney, liver or eye damage.
The authors conceded that their study was weakened by the lack of comprehensive air sampling immediately after the riots, but they have nevertheless red-flagged several residential areas near the gutted Cornubia warehouse north of Durban.
These include several “fence-line” residents of the Prestondale/Woodlands/Izinga area of Umhlanga and the informal settlement of Blackburn village.
The exact number of inhabitants of these areas is not stated in the study, but Blackburn village alone has more than 3 500 residents: the 2011 population census estimated there are more than 24 000 people in the greater Umhlanga area.
The authors noted that toxic fumes from the fire and smouldering phase may have affected a much larger area of the city, possibly beyond a 10km radius of the warehouse, which could have caused or aggravated respiratory problems and other acute health issues.
In some cases, the calculated hazard quotients suggest potential (but much lower) risks for other forms of non-cancer health impacts stretching as far as Verulam, La Lucia, Umdloti or Mt Edgecombe.
Remarkably, the latest health risk study was completed eight months ago but only published on 12 July on an electronic platform seldom accessed by the public.
It was produced by UPL consultants Apex Environmental, based on specialist advice from North West University toxicologist Professor Mary Gulumian, Wits University epidemiologist Professor Gill Nelson and inputs from numerous air quality consultancy groups.
The report suggests the “relative risks for cardio-pulmonary and lung cancer mortality were increased by a factor of two to three” for residents near Reddam House school in Umhlanga and in Blackburn village.
Relative risks are defined as the ratio of probability of adverse health events in an exposed group, compared with a group not exposed to high air pollution levels.
Any relative risk exceeding one is considered as an increased risk factor, yet the calculated risks are close to two in the vicinity of Blackburn and Reddam for cardiopulmonary death, and between 2.4 and three for lung cancer mortality.
Notably, these calculations are based on estimated levels of specks of particulate matter (PM2.5) in the air after the fire, not on a more comprehensive assessment of the toxic properties of a much wider variety of nearly 5 000 tonnes of pesticides, herbicides and other agrochemical products stored at UPL.
Gulumian and Apex said due to the widespread civil unrest at the time – and official ignorance about the exact nature of the chemicals stored at UPL until many days afterwards – it was not possible to measure the exact levels of individual toxic substances or cocktails thereof.
Therefore, based on the limited data available, the study focused mainly on predicted levels of PM2.5 as a metric.
“This is not to say all components of PM2.5 have the same toxicity, but rather that there is not, currently, evidence to quantify the effects of different components separately.”
Gulumian said a hazard quotient (HQ) below one indicates no adverse health effects were expected as a result of exposure – whereas more than half of the 101 locations in the study had hazard quotients exceeding one (indicating adverse health effects in people in these locations could be expected as a result of exposure – although this did not necessarily mean adverse effects would definitely occur).
Durban epidemiology expert Professor Rajen Naidoo, who was not involved in the study, said he was concerned about some of the methodologies used to predict health risks, and called for an independent peer review of the report.
Naidoo, who heads the Occupational and Environmental Health discipline at the University of KwaZulu-Natal and also conducted studies on health risks to people living next to the old Engen and Sapref petroleum refineries, said he was “uncomfortable” that the UPL health risks study focused on particulate matter, whereas health risks varied significantly depending on the toxicity of individual pesticides and mixtures thereof.
“PM2.5 is important as a carrier of pollutants, but the effects are going to be very different (if the study had been able to quantify UPL-specific chemical pollution levels).”
He also noted that new and complex chemical mixtures would have been generated during the UPL inferno, although the relative risks predicted in the Apex/Gulumian studies were nevertheless “extremely high”.
Gulumian wrote that the hazard quotients for more than half of the more than 100 residential sites in the study had indicated “high to exceptionally high risk” for developing non-cancer adverse health effects.
“Exposure to atmospheric emissions generated from the UPL fire is considered to have been episodic and acute. The significance of the acute exposure would have been greater in some areas than others and, therefore, the likelihood of long-term health effects occurring within the communities of concern is considered possible.”
The authors have recommended a series of steps to monitor and investigate the possible long-term health effects for communities based on different ages and sexes, genetic predispositions or pre-existing health conditions.
Further investigations and monitoring were needed to ascertain the likelihood of “internal exposure” of individuals, including lung function tests and eye and skin examinations.
The potential for long-term health effects associated with exposure to atmospheric emissions cannot be ruled out, they said. A retrospective cohort study should be conducted to assess the prevalence of long-term health effects, and include:
1. All individuals living in the exposed communities at the time of the fire.
2. The firefighters and others involved in extinguishing the fire.
Naidoo suggested the new studies should be completely independent of UPL.
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