[Blog 10] Shipping’s Toxic Legacy: The Environmental Impacts of Ship Disposal

As we conclude our exploration of shipping pollution, this blog focuses on a lesser-known yet equally pressing issue: the pollutive impacts of shipbreaking. In particular, a recent study measuring toxic heavy metal concentrations at Bangladesh’s shipbreaking sites by Ali et al (2022), has resurfaced environmental concerns about shipbreaking activities around the world. 

What is shipbreaking and why is it pollutive? 

Shipbreaking refers to the act of breaking down retired ships for the recycling of valuable materials such as wood and steel (Abdullah et al., 2013). However, several studies have previously raised concerns about the highly pollutive nature of shipbreaking– largely due to the spillage and leakage of hazardous elements (Reddy et al., 2004; Hossain & Islam, 2006; Neser et al., 2012; Pasha et al., 2012). This is because ships being scrapped contain many different hazardous wastes. These include: 

• Heavy metals in the form of mercury, lead, and arsenic can be found in electric wastes such as fluorescent light tubes, thermometers, batteries, electrical switches, light fittings, and fire detectors. A large amount of copper is present in various electrical wiring, while iron forms a big part of the ship’s body. (Baura et al., 2017).
• Chromium can be found in ballast water (mentioned in blog 2) (Baura et al., 2017)
• Up to thousands of litres of petroleum hydrocarbons (e.g. Engine oil, blige oil, hydraulic and lubricant oil), as well as sealants which contain hazardous pentachloro benzene (Al-Mamun et al., 2017). 

As aforementioned, through spillage and discharge, these hazardous wastes are then leaked and mixed into coastal environments, contaminating beach sediments, sea and groundwater (Hasan et al., 2013). The toxicity of these pollutants subsequently poses a threat to marine biodiversity and to human public health (Ali et al., 2022). This is especially so for heavy metals, which not only have the propensity to bioaccumulate but are also non-biodegradable (Siddiquee et al., 2012). 

Case study: Chittagong shipbreaking yard, Sitakunda

The Chittagong shipbreaking yard, along the 20km coastal strip of Sitakunda, is the world’s largest shipbreaking yard, handling about a fifth of the world’s total shipbreaking (pathfriend-bd, n.d.). 

In Ali et al (2022) study of toxic metal pollution in the Sitakunda shipbreaking area in Bangladesh, their sampling of the concentration of four toxic metals (As, Cr, Cd, and Pb) in water and sediment at 10 different sampling sites over summer and winter (Figure 1), has yielded the following key results:  

1. Concentration of all four toxic metals (As, Cr, Cd, and Pb) exceeded WHO recommended acceptable limits (Table 1). 
2. Metal pollutive index (MPI) of water quality (derived by Mohan et al., 1996) revealed that MPI levels recorded (Range of 140.12 to 402.15) exceeded the critical score of 100 (MPI >100 is considered as polluted). 
3. Geoaccmulation index (measurement of contamination of toxic metals in sediments, derived by Muller, 1969) revealed Cd to be “strongly contaminated,” Pb to be “moderately contaminated,” and As was found to be “uncontaminated to moderately contaminated” (Table 2).
4. Calculation of Potential ecological risk index (Eri) and the Risk Factor (RI), which sums of all risk factors for toxic metals in the sediments (derived by Hakanson, 1980), has suggested that  the Sitakunda ship breaking area was at very high ecological risk due to metals pollution (Table 3). 
5. As and Cd showed significant seasonal variation (water and sediment) seasons, while Pb and Cr had no seasonal impact.

Overall, Ali et al. (2022) study revealed significant levels of toxic metal pollution present in the coastal strip of Sitakunda, as a result of shipbreaking activities. Crucially, the area currently faces high ecological risk, as a result of high levels of metal pollution.

Figure 1: Map showing the sampling sites of the Sitakunda ship-breaking area of the Bengal coast, Bangladesh. (Ali et al., 2022).

Table 1: Comparison of results of concentration of four toxic metals (As, Cr, Cd, and Pb) with WHO recommended allowable limit. (extracted from Ali et al., 2022)

Table 2: Comparison of results of geo-accumulation index (Igeo) of four toxic metals (As, Cr, Cd, and Pb). A seven-tiered classification system of Igeo provided by Muller (1969) is defined as Igeo ≤ 0-practically unpolluted; 0 ≤ Igeo ≤ 1-unpolluted to moderately polluted; 1 ≤ Igeo ≤ 2-moderately polluted; 2 ≤ Igeo ≤ 3-moderately to strongly polluted; 3 ≤ Igeo ≤ 4-strongly polluted; 4 ≤ Igeo ≤ 5-strongly to extremely polluted; and 5 < Igeo-extremely polluted (extracted from Ali et al., 2022).

Table 3: Potential ecological risks (PERI) and Risk Index (RI) for toxic metals in sediment investigated from the Bay of Bengal coast around the shipbreaking area of Bangladesh for summer and winter. Eri is defined as the monomial potential ecological risk factor, while RI determines the extent to which toxic metal pollution had contaminated the sediments, based on the toxicity of poisonous metal pollution and the environment’s response (Hakanson, 1980). The potential ecological risk for single metal (Eri)) follows a level as low risk ( Eri)< 40); moderate risk (40 ≤ Eri)< 80); considerable risk (80 ≤ Eri)< 160); high risk (160 ≤ Eri)〈320); very high risk ( Eri)≥ 320). Considering the total toxic metals, RI follows a ranking with: low risk (RI < 95); moderate risk (95 ≥ RI < 190); considerate risk (190 ≥ RI < 380); very high risk (RI > 380) (extracted from Ali et al., 2022).

Negative ecological impacts of toxic metal pollution, on marine biodiversity and to human health

As explored by several authors, toxic metal pollutants have negative effects on marine organisms. Table 4 highlights several of the effects that toxic metals have on marine organisms. Furthermore, as such heavy metals have high accumulation potential, they accumulate in aquatic organisms as well as through agricultural soil, rising levels of toxic metals contamination also have a direct negative impact on human health as they are such toxic metals are transferred through the food chain (Ahmed et al., 2020; Bryan & Hummerstone, 1977; Lee et al., 2019; Proshad et al., 2021). 

Table 4: The effects of toxic metals on marine organisms. (Sadiq, 1992).

Moving forward 

It is important to note that while Ali et al (2022) study has highlighted the effects of shipbreaking on increasing toxic metal concentration, it was not the first study to do so. Siddiquee et al (2012) have similarly found high concentrations of several heavy metals (Zn, Pb, Cr) in the same area– the Chittagong shipbreaking yard, 10 years ago (Figure 2). Therefore, while these studies have highlighted the high concentration of toxic metals present at such shipbreaking sites, little action has been taken to address this issue, despite their negative pollutive impacts on the surrounding biodiversity and human health. This further supports previous blogposts’ arguments that the pollutive impacts of the shipping industry are often sidelined. Moving forward, more concrete actions need to be taken in order to better mitigate and reduce the pollutive impacts on the shipbreaking industry (Ali et al., 2022). 

Figure 2: Comparison of trace metals in affected, controlled and standard values. (Siddiquee et al., 2012)

References

Abdullah, H. M., Mahboob, M. G., Banu, M. R., & Seker, D. Z. (2013). Monitoring the drastic growth of ship breaking yards in Sitakunda: A threat to the coastal environment of Bangladesh. Environmental Monitoring and Assessment, 185(5), 3839–3851. https://doi.org/10.1007/s10661-012-2833-4

Ahmed, A. S. S., Hossain, M. B., Semme, S. A., Babu, S. M. O. F., Hossain, K., & Moniruzzaman, M. (2020). Accumulation of trace elements in selected fish and shellfish species from the largest natural carp fish breeding basin in Asia: A probabilistic human health risk implication. Environmental Science and Pollution Research, 27(30), 37852–37865. https://doi.org/10.1007/s11356-020-09766-1

Ali, M. M., Islam, Md. S., Islam, A. R. Md. T., Bhuyan, Md. S., Ahmed, A. S. S., Rahman, Md. Z., & Rahman, Md. M. (2022). Toxic metal pollution and ecological risk assessment in water and sediment at ship breaking sites in the Bay of Bengal Coast, Bangladesh. Marine Pollution Bulletin, 175, 113274. https://doi.org/10.1016/j.marpolbul.2021.113274

Habibullah-Al-Mamun, Md., Ahmed, Md. K., Raknuzzaman, M., Islam, Md. S., Ali, M. M., Tokumura, M., & Masunaga, S. (2017). Occurrence and assessment of perfluoroalkyl acids (Pfaas) in commonly consumed seafood from the coastal area of Bangladesh. Marine Pollution Bulletin, 124(2), 775–785. https://doi.org/10.1016/j.marpolbul.2017.02.053

Hakanson, L. (1980). An ecological risk index for aquatic pollution control: A sedimentological approach. Water Research, 14(8), 975–1001. https://doi.org/10.1016/0043-1354(80)90143-8

Hasan, A. B., Kabir, S., Selim Reza, A. H. M., Zaman, M. N., Ahsan, M. A., Akbor, M. A., & Rashid, M. M. (2013). Trace metals pollution in seawater and groundwater in the ship breaking area of Sitakund Upazilla, Chittagong, Bangladesh. Marine Pollution Bulletin, 71(1–2), 317–324. https://doi.org/10.1016/j.marpolbul.2013.01.028

Hossain, M. M. M., & Islam, M. M. (2006). Ship breaking activities and its impact on the coastal zone of Chittagong, Bangladesh: Towards sustainable management. Advocacy & Publication Unit, Young Power in Social Action (YPSA). https://www.ypsa.org/publications/Impact.pdf

Lee, P.-K., Yu, S., Jeong, Y.-J., Seo, J., Choi, S., & Yoon, B.-Y. (2019). Source identification of arsenic contamination in agricultural soils surrounding a closed Cu smelter, South Korea. Chemosphere, 217, 183–194. https://doi.org/10.1016/j.chemosphere.2018.11.010

Mohan, S. V., Nithila, P., & Reddy, S. J. (1996). Estimation of heavy metals in drinking water and development of heavy metal pollution index. Journal of Environmental Science and Health. Part A: Environmental Science and Engineering and Toxicology, 31(2), 283–289. https://doi.org/10.1080/10934529609376357

Muller, G., 1969. Index of geoaccumulation in sediments of the Rhine River. GeoJournal 2, 108–118. 

Neşer, G., Kontas, A., Ünsalan, D., Altay, O., Darılmaz, E., Uluturhan, E., Küçüksezgin, F., Tekoğul, N., & Yercan, F. (2012). Polycyclic aromatic and aliphatic hydrocarbons pollution at the coast of Aliağa (Turkey) ship recycling zone. Marine Pollution Bulletin, 64(5), 1055–1059. https://doi.org/10.1016/j.marpolbul.2012.02.019

Pasha, M., Mahmood, A. H., Rahman, I., & Hasnat, A. (2012, May). Assessment of ship breaking and recycling industries in Bangladesh – An effective step towards the achievement of environmental sustainability. In International conference on agricultural, environmental and biologica. 

Pathfriend Tour Operator. Chittagong ship breaking yard. https://pathfriend-bd.com/explore_bd/chittagong-ship-breaking-yard/

Proshad, R., Islam, S., Tusher, T. R., Zhang, D., Khadka, S., Gao, J., & Kundu, S. (2021). Appraisal of heavy metal toxicity in surface water with human health risk by a novel approach: A study on an urban river in vicinity to industrial areas of Bangladesh. Toxin Reviews, 40(4), 803–819. https://doi.org/10.1080/15569543.2020.1780615

Reddy, M. S., Basha, S., Sravan Kumar, V. G., Joshi, H. V., & Ramachandraiah, G. (2004). Distribution, enrichment and accumulation of heavy metals in coastal sediments of Alang–Sosiya ship scrapping yard, India. Marine Pollution Bulletin, 48(11–12), 1055–1059. https://doi.org/10.1016/j.marpolbul.2003.12.011

Sadiq, M. (1992). Toxic metal chemistry in marine environments. Marcel Dekker.

Siddiquee, N. A., Parween, S., Quddus, M. M. A., & Barua, P. (2012). Heavy metal pollution in sediments at ship breaking area of Bangladesh. In V. Subramanian (Ed.), Coastal Environments: Focus on Asian Regions (pp. 78–87). Springer Netherlands. https://doi.org/10.1007/978-90-481-3002-3_6

​​Barua, P., Rahman, S.H., Molla, M.H., 2017. Heavy metals effluence in sediments and its impact on macrobenthos at shipbreaking area of Bangladesh. Asian Profile 45 (2), 167–180.