Industrialization includes the rapid growth in manufacturing and production as well as technological changes. Growth is required for better productivity, an increase in the standard of living, growth in population, urbanization and more. The rise in urbanization is also expected to go up to 60% by 2030. However, this transformation is causing a drastic change in Earth’s ecosystem, negatively impacting the environment with air pollution, topsoil contamination, groundwater contamination and water pollution. Industrial wastes are more toxic compared to municipal wastes because of the presence of oil, grease, heavy metals, phenols, ammonia and more [1]. Emissions from mining, power plants and refineries are some of the major sources of hazardous toxic chemicals that pollute the environment.

Soil pollution is characterized as the accumulation of persistent toxic compounds, chemicals, salts, radioactive materials, or disease-causing agents, which adversely affect plant growth and animal health in soils. This pollution decreases the quality of the crop as the effect of using of pesticides and chemical fertilizers. Exposure to toxic and dangerous chemicals can increase the health risks to people living nearby and on polluted land. For example, heavy metals can enter humans’ bodies through food, water, air and bioaccumulation over a period of time [2]. This could lead to acute and chronic illness in the central nervous system and peripheral nervous system [3]. Moreover, the toxic effects of heavy metals can cause an imbalance in the ecosystem of the soil. Heavy metals in soils exist in four different forms: dissolved ions, organic complexes, exchangeable ions and precipitates [4]. These compositions are dangerous because they tend to bioaccumulate in plant tissues. Metals such as zinc (Zn), nickel (Ni), manganese (Mn), iron (Fe) and copper (Cu) do contribute their importance in plant growth and help physiological processes such as the electron transfer system in photosynthesis. Other metals such as cadmium (Cd), arsenic (As), chromium (Cr), mercury (Hg) and lead (Pb) do not carry any known biological roles in plants. However, an excessive amount of heavy metal will affect biological and biochemical processes negatively by restraining growth and lowering the chlorophyll content of the plants. For instance, a plant with high lead concentrations fastens the production of reactive oxygen species (ROS), causing lipid membrane damage that ultimately leads to damage of chlorophyll and photosynthetic processes and suppresses the overall growth of the plant [5].

Heavy metal contamination in soil has a negative impact on the environment, especially on soil quality and plant growth. Once the plant is saturated with heavy metal, the plant dies due to the interruption in photosynthesis and protein synthesis. Elimination of heavy metals is difficult as it is irreversible and remediation needs to be done. Remediation can be divided into in-situ and ex-situ remediation. In-situ remediation is a process of remediation that does not require transport of contaminated soil to off-site treatment facilities. Ex-situ remediation, on the other hand, is the remediation technique that requires excavation of contaminated soil to an off-site treatment facility [4]. This process requires additional costs. However, the treatments are controlled and accelerated and provide better results in a shorter time. Examples of in-situ remediation are surface capping, encapsulation, electro-kinetics, soil flushing, immobilization, phytoremediation and bioremediation. Examples of ex-situ remediation techniques are landfilling, soil washing, solidification and vitrification [4].

Phytoremediation is a cost-effective remediation technique with ecological benefits and high public acceptance. This method is scientifically proven for the remediation of contaminants with the only limitations being the time-consuming process and the possibility of adverse effects on living beings due to biomagnification. This limitation can be overcome using non-edible commercial plants that have rapid growth rates and are easy to maintain. With these characteristics, a bast fiber plant with various plant parts is a good option for phytoremediation. They are also used in the production of a variety of products, such as paper, textiles, wrapping materials, rope, strings, baskets and so on, which will improve the socioeconomic status of people who live in contaminated areas or who use contaminated lands for agricultural purposes. Bast fibre, also known as phloem fibre, is a type of plant fibre derived from the phloem or bast that surrounds the stem of certain dicotyledonous plants. Bast fibres plants can be obtained from either cultivated herbs such as Flax, Hemp and Ramie, or from wild plants such as linden, wisteria and mulberry. The physical properties of different bast fibers that possess a series of characteristics: (1) ability to accumulate metals preferable in the above parts, (2) tolerance to accumulated metal concentrations, (3) production of high biomass and (4) not consumable by humans and animals, making them suitable for use in phytoremediation [6,7].

It is also crucial to understand that edible plants are not appropriate for phytoremediation because they may affect the health of humans or animals once they are consumed [8]. Therefore, fiber crops are said to be the best fit for phytoremediation. This is because fiber plants involve a cycle of planting and harvesting, which help to reduce the heavy metal contamination in the soil over time, and the harvested fiber is used to manufacture biomaterials such as paper and textiles. In this case, it does not enter the food chain and affects the environment negatively, such as harming humans or animal health. Apart from that, different plants have different methods for the removal and accumulation of heavy metals (Figure 1). For example, some plants can stabilize or decrease the mobility of the pollutants in the soil through accumulation in the roots through root hairs to stop contaminants’ run-off, bulk erosion and air-borne transport [9]. Other plants may be involved in the process of plant uptake and release into the atmosphere through transpiration, which is known as phytovolatilization. Many phytoremediation processes are possible through better relationships in between plants, microbes, soil and contaminants. These different processes of phytoremediation perform different management options for a better end product to the environment [6].

This paper discusses the potential of four commonly used bast fiber plants namely Cannabis sativa (Hemp), Hibiscus cannabinus (Kenaf), Corchorus olitorius (Jute) and Linum usitatissimum (Flax) for phytoremediation of selective heavy metals, such as cadmium (Cd), lead (Pb) and zinc (Zn) from contaminated soil. The main goal of this paper is to provide references for suitable bast fiber plants for heavy metal treatment. In addition, this review summarises these plants’ ability to accumulate heavy metal elements and reveals their potential for use as phyotoaccumulators or phytostabilizers via their uptake mechanisms. This emerging technology can be improved with natural and chemical amendments that make heavy metals bioavailable and soluble.