Media statements

Exposure to mercury in communities living alongside the Inanda Dam

Prof. Tony Mbewu, President of the South African Medical Research Council, today announced that a study conducted by the MRC’s Environment and Health Research Unit (EHRU) revealed high levels of exposure to mercury in some people living in villages alongside the Inanda Dam in KwaZulu-Natal.

“This is an important public health finding,” he said, “not least because of the serious health effects associated with mercury exposure, including impacts on cognitive thinking, memory, attention, language, and fine motor and visual spatial skills.” He added that at higher concentrations mercury exposure could result in the impairment of peripheral vision, a feeling of "pins and needles" in the hands, feet and mouth area, a lack of coordination of movements, impaired speech, hearing and walking, as well as muscle weakness.    

“We conducted the study because we were interested to see what the levels of mercury exposure are in downstream communities, around 20 years after massive amounts of mercury were released from the former Thor Chemicals plant,,” said Prof. Angela Mathee, Director of the MRC Environment unit in which the study was undertaken. The reason for our interest was that mercury is well known, under certain circumstances, to concentrate or “bio-accumulate” over time.

A stream just below the former Thor Chemicals plant is adjacent to the Umgeni River, which in turn, feeds into the Inanda Dam. The study was conducted in three villages along the banks of the Inanda Dam – Mshazi, Nqetho and Madimeni.   

“We were troubled by the study results showing elevated levels of mercury in 17% of the 86 human hair samples, and in half of the small sample (10) of fish captured from the Inanda Dam,” said Prof. Mathee. She went on to say that analysis of sediment samples taken from the Inanda Dam and the Umgeni River had low levels of mercury, but that extremely high concentrations of mercury had been found in sediment taken from the Mngceweni stream immediately downstream from the former Thor Chemicals plant.

When asked about the source of the mercury, Prof. Mathee said that the design and scale of the study were not appropriate to say with certainty whether the source was current or historical, or a combination, or even whether multiple sources were involved. She, however, emphasized the need for an urgent investigation into the sources of the mercury, as well as the reason for the highly elevated levels of mercury in the stream below the former Thor Chemicals plant, and whether seepage of mercury from this point into the local environment and river system was an ongoing occurrence or not.

Prof. Mathee explained that the study had actually been conducted on a relatively small scale as a research project for a PhD student, Ms Vathiswa Papu-Zamxaka. Ms Papu-Zamxaka’s work had been steered and supervised by a team of local and international experts from the MRC, the University of the Witwatersrand and London South Bank University.

“Notwithstanding its small scale, Ms Papu-Zamxaka’s research study has been instrumental in revealing an important public health problem, and catalysing inter-sectoral action to investigate and address it,” said Prof. Mbewu.

“I never imagined that my study would expose anything of this nature,” said Ms Papu-Zamxaka, adding that mercury was a highly toxic substance, and that she hoped interventions would soon be implemented to reduce mercury exposure in the area. “I am grateful to all the people who were willing to participate in my study, and to the many colleagues who helped along the way, such as those from the Council for Geoscience,” she said. According to Papu-Zamxaka every attempt had been made to reach, and offer, the study participants with elevated hair mercury levels, referrals for assessment at a nearby hospital.

Prof. Mbewu said that the study findings had been presented to various stakeholders at provincial and local government level in KwaZulu-Natal, where a task team had been set up to further investigate the problem and decide on the necessary action. Early results from the additional investigations commissioned by the task team appeared to confirm the findings of the MRC study.

Prof. Mbewu ended by saying that in line with standard MRC research processes, the detailed research findings had been written up and submitted to a scientific journal for review.

 END

Medical Research Council contact:

Prof. Angela Mathee
amathee@mrc.ac.za
011 274 6078 (office telephone)
011 642 6832 (facsimile)
082 464 7038 (cellular telephone)
PO Box 87373, Houghton, 2041, South Africa (postal address)
Medical Research Council, Broll Place, Sunnyside Office Park, 4 Carse O’Gowrie Avenue, Parktown, 2193 (physical address).