Minamata, Japan 1960s. Source: The Asia Pacific Journal

It all began in early 1956, where an unprecedented phenomenon had arisen among the quite waters of Minamata Bay. A growing number of people experienced a deterioration in limb control, spiralling into the inability to eat or speak, and eventually death. During that period, a high 10% of new-borns had cerebral palsy-like conditions (Kitamura et al., 1959). Not long before, numerous fishes died, and cats moved in a drunken manner before their demise (Yokoyama, 2018).

As cases of this strange illness, then named “Minamata Disease”, began to spread to other nearby coastal communities, the action committee formed had suspicions of seafood poisoning (Tsuda, 2014). However, the seafood production and consumption were only intermittently stopped in favour of economic activity (Takamine, 2016).

Chisso Factory, Minamata. Source: The Japan Times

After three years of extensive research, the action committee submitted a conclusive report in 1959, detailing the high concentrations of organic mercury in Minamata Bay’s organisms and afflicted humans. The point source being the direct discharge of Chisso’s factory wastewater into Minamata Bay.

Infographic on bioaccumulation and biomagnification. Source: Hoop (2013)

A by-product of acetaldehyde’s production, the wastewater had contained inorganic mercury. Upon entering water, this heavy metal was converted by marine bacteria into its more toxic organic form, methylmercury. This hazardous compound is the absorbed by marine organisms, such as through the gills or skin of fish and the consumption of methylmercury contaminated plankton by fish (Silver et al., 1994). The process of bioaccumulation sees the increase in concentration of methylmercury within organisms as it ages. This occurs in tandem with biomagnification, where toxins are transferred to the next consumer along the food chain. Residing at the tail-end of the food chain, humans thus end up with the highest concentration of methylmercury, resulting in extensive damage to the nervous system (Iguruchi, 2014).

Despite such incriminating evidence and awareness of their pollutive activities, Chisso denied all allegations and continued to discharge mercury contaminated wastewater into Minamata Bay. Chisso’s act of impunity was exacerbated by a lack of governmental response, where only in 1968 was Chisso’s involvement officially recognised (Ministry of Environment, 2013). Throughout the 12 years of inaction to the mercury poisoning, an approximate 640kg of methylmercury had already flowed into the sea, poisoning and destroying the health of approximately 200, 000 people (Hill, 2020).

The mercury pollution incident had garnered extensive attention both within Japan and worldwide, leading to the implementation of Japan’s Water Pollution Law in 1970 and the global regulation of mercury pollution through the Minamata Convention on Mercury in 2013. Through consolidating research, the Minamata Convention has considered the numerous aspects of mercury pollution and appropriate management measures. However, there still remains areas for improvement, such as the mismatch in implementation of mercury regulations at the international and national level.

In all, the Minamata tragedy serves as a reminder of the consequences of unchecked mercury pollution, paving a path for its sustainable production and disposal.

 

References:

Enviromental Protection Authority Victoria. (2021, August 25). Point and non-point sources of water pollution. Retrieved from: https://www.epa.vic.gov.au/for-community/environmental-information/water/protecting-victorias-waters/point-and-non-point-sources-of-water-pollution#:~:text=A%20point%20source%20is%20a,the%20sea%20in%20this%20way.

Gerson, J. (2022, January 28). Gold Mining Is Poisoning Amazon Forests with Mercury. Scientific American. Retrieved from: https://www.scientificamerican.com/article/gold-mining-is-poisoning-amazon-forests-with-mercury/

Hill, M. K. (2020). Understanding environmental pollution (Fourth). Cambridge University Press.

Iriguchi N (2014) When did Japanese know the organic mercury poisoning? Monthly Hodanren 1174:35–40.

Kitamura S, Hirano H, Noguchi Y, Kojima T, Kakita T, Kuwaki H (1959) Epidemiological studies on “Minamata disease” (Supplementary report no. 2). Kumamoto Igakkai Zasshi 33

Minamata Convention on Mercury. (2021). About us. Retrieved 20 January, 2023 from https://www.mercuryconvention.org/en/about

Ministry of the Environment, Japan (2013) Lessons from Minamata Disease and Mercury Management in Japan. https://www.env.go.jp/chemi/tmms/pr-m/mat01/en_full.pdf. Accessed 20 January 2023

Ministry of the Environment, Japan (2023). Water Pollution Control Law_Chapter II-1. Retrieved January 20, 2023 from https://www.env.go.jp/en/laws/water/wlaw/ch2-1.html

National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 177, Acetaldehyde. Retrieved January 20, 2023 from https://pubchem.ncbi.nlm.nih.gov/compound/Acetaldehyde.

Silver S, Endo G, Nakamura K (1994) Mercury in the environment and the laboratory. J Jpn Soc Water Environ 17:83–145

Tsuda T (2014) What do medical scientists do at the time of environmental pollution problems? Iwanami Shoten, Tokyo

Takamine T (2016) Do you know about Minamata disease? Iwanami Shoten, Tokyo

Yokoyama, H. (2018). Mercury Pollution in Minamata. Springer Nature.