Environmental Engineering Reference
In-Depth Information
18.2.4 Potential Risks of Nanoparticles
To assess the potential risk of nanoparticles, we need to consider the full life cycle of the
products from resources to disposal of remaining waste. In fact, the effect of exposure to
nanomaterials, from handling them at water treatment plants to drinking them in treated
water, is not yet known. However, there are concerns that their small size and enhanced
reactivity may make them more toxic. Their small size makes their escape and diffusion
into the environment quite easier.
In ongoing researches, scientists are evaluating the potential health and environmental
risks of using nanotechnology in water applications. For instance, there is a special pro-
gram working on EHS issues of incorporation of iron nanoparticles into groundwater in
Venice (Italy) for remediation purposes. Investigations regarding the ethical, legal, and
social implications of nanotechnology also are under way. Because of the generally lower
scientiic capacity in emerging countries, there is concern that effective regulation of any
discovered risks will lag behind that of developed countries. The EHS issues should be con-
sidered at all stages of life cycle, i.e., raw materials, research and development (R&D), manu-
facturing, consumer use, recycling, and disposal stages, as discussed in previous sections.
In summary, it can be stated that for water treatment, nanomaterials are neither “nano-
angels” nor “nano-demons.” In the next section, the EKC concept is discussed.
18.3 Environmental Kuznets Curve
On the basis of the Kuznets work, Grossman and Krueger developed the EKC, which
discloses the relationship between environmental degradation and economic growth
(Grossman and Krueger, 1995). They used national GDP data and various indicators
of local environmental conditions via panel data from GEMS (United Nations Global
Environment Monitoring System). The results showed that for most indicators (pollutants
in air and water), economic growth brings an initial phase of deterioration followed by a
subsequent phase of improvement. The turning points, i.e., GDP peak, for different water
pollutants vary; however, in most cases, they occur before a country reaches a per capita
income of $8000 (see Table 18.4).
TABLE 18.4
Turning Points for Some Water Pollutants in Rivers
Pollutant
Turning Point (Peak GDP), USD (1985)
Standard Errors
Dissolved oxygen
2703
5328
BOD
7623
3307
COD
7853
2235
Nitrates
10,524
500
Lead
1887
2838
Cadmium
11,632
1096
Arsenic
4900
250
Mercury
5047
1315
Source:
Grossman, G.M., Krueger, A.B.,
J. Econ
., 110, 353, 1995.
Note:
BOD, biochemical oxygen demand; COD, chemical oxygen demand.
