Page 11 - EER-2-3

Explora: Environment
and Resource Environmental contamination of titanium

process results in absolute Ti losses on the profile 2.2. Ti contamination from anthropogenic activity
scale. Assessment of the mineral reactivity of Ti in soil Concerns about Ti as an emerging contaminant have
indicates the movement of Ti at both the centimetric been largely focused on anthropogenic activity. Table 1
and profile scales, either as a dissolved element or as an lists studies describing Ti contamination in the air/dust,
organometallic compound. Furthermore, a large amount mining zones, and sediments.
of Ti is recycled by vegetation, which also increases Ti
mobility in soils. These findings indicate that a soil’s Ti 2.2.1. Ti mining sites and associated contamination of
46
content may be largely influenced by the weathering of Ti soils and sediments
minerals, except for certain tropical soils.
Interestingly, there is limited information on environmental
In addition to Ti minerals, coal is rich in Ti. The Ti contamination resulting from mining activity. The
concentrations in coal samples collected from Colorado, Panzhihua region in Sichuan province, China, is the
Pennsylvania, Texas, and Washington, US, ranged from world’s largest vanadium-Ti magnetite deposit. Yanguo
2,800 to 6,500 mg/kg. Meanwhile, the Ti concentrations et al. reported that concentrations of heavy metals were
47
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in 37 coal samples collected at Xuzhou-Datun coal mine higher in the topsoil of the Panzhihua region, with Ti
district, Jiangsu province, China, ranged between 266 ranging from 0.29% to 0.44%, and Ti in stream sediments
and 7,430 mg/kg. The combustion of coal results in the ranging from 0.37% to 5.28%. Based on the Muller index
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production of Magnéli-phase Ti oxides—nanoscale Ti ofgeoaccumulation, the authors concluded that metal
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suboxides (Ti O 2x−1 , where 4 ≤ x ≤ 9)—whose toxicity pollution was more serious in the sediment than in the
x
hazards on human health are still unknown. The soils. Similarly, high concentrations of Ti, along with other
49
physicochemical characteristics of TiO NPs have the
2
potential to significantly impact both their toxicity heavy metals, were identified in a Ti mining site in Kwale
and bioavailability. Researchers have documented that County, Kenya, where Ti concentrations ranged from
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anataseTiO NPs are cytotoxic or genotoxic. 48,49 Inhalation 0.47% to 2.8%. Another study was also conducted in
2
of TiO NPs is often reported as the primary exposure Kwale at a distance of 2.86 km from the Ti mining plant,
2
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pathway in the human body during occupational exposure. and the Ti content of the soils ranged from 0.3% to 1.5%.
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Additionally, exposure to nano-TiO has been shown to Based on the data from Kabata-Pendias and Pendias, Ti
2
have negative consequences, including oxidative stress content in surface soils varied from 0.1% to 0.9% with a
in human cells and genetic instability in animals. When mean value of 0.35%. Ti soil concentrations higher than a
exposed to TiO NPs, the two most significant impacts background level could indicate potential risks to sensitive
2
reported in experimental animals (mice and rats) are species.
lung cancer and pulmonary inflammatory reactions. 41-43 2.2.2. Airborne particulate matter and dust
Zeman et al. reported that when actual dosages were the
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only factor taken into account, as in certain inhalation Airborne particulate matter (PM) is known to be a group 1
experiments, inflammatory reactions resulted in noticeable carcinogen to humans due to the presence of contaminants,
adverse effects. Through the lung or gastrointestinal tract, such as polycyclic aromatic hydrocarbons (PAHs)
TiO NPs enter the systemic circulation and are distributed (e.g., benzo(a)pyrene, nitro-PAHs, and quinones) and
2
to the brain, spleen, liver, and kidneys, subsequently heavy metals (e.g., vanadium, copper, iron, and nickel). In
exerting localized toxicity. 46,47 an industrial suburban station located in Langreo, Spain,
3
A limited number of in vivo and in vitro studies have Ti in the PM was 15.3 ng/m , which was determined to
10
noted specific reproductive and developmental toxicity in be of anthropogenic origin from the use of coal and coke
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experimental animals or cell cultures. 46-48 It is unknown if production. In China, coal burning is a major contributor
human exposure to TiO NPs results in similar toxicities. to PM. Ti concentration in the fallen dust in arid and semi-
2
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According to research on animals, prolonged exposure arid Northern China was detected at 3,600 mg/kg. In the
(environmental) may cause TiO NPs to accumulate in dust storms of arid and semi-arid Northwest China, Ti
2
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organs or tissues. Furthermore, at relatively high doses, concentrations ranged from 2,558.1 to 3,342.6 mg/kg.
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TiO NPs induce reactive oxygen species production and Furthermore, indoor air pollution is a major global public
2
cell signal transduction pathway alteration, likely playing health threat. A study conducted in Columbia and South
a key role in the etiology of TiO -NP carcinogenesis. 49,51 In Carolina, US, showed that the concentration of Ti in
2
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general, TiO NPs are more harmful than TiO 2 house hold dust ranged from 0 to 8,000 mg/kg, primarily
2
microparticles. Additional details on Ti toxicity are due to anthropogenic releases from paint during home
presented in Supplementary Information 1. renovations.
Volume 2 Issue 3 (2025) 5 doi: 10.36922/EER025130027