Thor Chemicals, Cato Ridge

A mercury 'recovery' plant west of Durban that in the 1980s and early 1990s took in mercury waste from US and European companies. Workers died of poisoning, mercury reached the Umgeni river catchment and the waste stockpile stayed on site for decades: a reference case in the debate on the international trade in hazardous waste.

Status

Remediation under way

The plant has been idle since the 1990s, but the mercury waste stayed in storage for about thirty years. By April 2021 just over 1,000 tonnes had been shipped to Switzerland for treatment in 57 sea-freight containers (Daily Maverick, reposted by the Basel Action Network). We found no source on the completion of the removal or on the clean-up of soil and groundwater.

Story

The British company Thor Chemicals started its Cato Ridge plant in 1978. In the 1980s and early 1990s the plant took in mercury-bearing waste for reprocessing from US and European companies, among them American Cyanamid and Borden Chemicals (IPS, 2001).

In July 1988 the local water board found mercury in the Umgeni river; in 1990 Greenpeace sampled soils around the plant and measured high deposits. A health screening in 1992 found nearly 30% of the workers at risk of severe poisoning. Sources differ on the number of deaths: two workers according to IPS (2001), at least four according to the Daily Maverick (2021), with others left disabled. The closure date is also reported differently: 1991 in the Daily Maverick, 1994 in IPS.

A commission of inquiry concluded in 1996 that the state shared responsibility for failures of oversight. In 1998 the families of the dead workers were awarded nearly 2 million dollars, and in 2000 another twenty workers received about 400,000 dollars in total. The company in South Africa later took the name Guernica Chemicals. The waste stayed in storage, in leaking barrels; in August 2019 a fire burned about 30% of it. The British group then agreed to pay nearly 174 million rand to ship the waste to Batrec Industries at Wimmis, Switzerland.

Timeline

1978Thor Chemicals starts the Cato Ridge plant.

1988July: the local water board finds mercury in the Umgeni river.

1990Greenpeace samples the soils around the plant.

1992Health screening: nearly 30% of workers at risk of severe poisoning.

1996The commission of inquiry assigns part of the responsibility to the state's failures of oversight.

1998Nearly 2 million dollars awarded to the families of the dead workers.

2019August: a fire burns about 30% of the stored waste.

2021April: just over 1,000 tonnes removed in 57 containers, bound for Switzerland.

Health

Occupational mercury poisoning: between two (IPS, 2001) and at least four (Daily Maverick, 2021) workers died in the early 1990s and others were left disabled; in 1992 nearly 30% of the workers screened were at risk of severe poisoning. Downstream, 50% of fish samples from a dam exceeded WHO safety limits for mercury and fishing at Inanda Dam, about 30 km away, was temporarily banned (Daily Maverick, 2021).

From the literature

Species that acted on one of this site's contaminants in at least one study. The list is automatic and takes no account of this site's soil, concentrations or climate.

Plants

Eichhornia crassipesWater hyacinthMercuryEvidence: field
Azolla carolinianaCarolina mosquito fernMercuryEvidence: laboratory

Fungi

Aspergillus nigerBlack mouldMercuryEvidence: laboratory
Rhodotorula taiwanensisMercuryEvidence: laboratory
Boletus edulisKing bolete, porciniMercuryEvidence: survey of wild specimens