Environmental Engineering Reference
In-Depth Information
points, neurological problems, and renal damage. In one study, the effects of
E-waste toxicants were addressed for a random selection of 429 adolescent and
361 adult subjects (Ketelslegers et al.
2008
). These subjects were genotyped for 36
polymorphisms in 23 genes, selected because of their known role in carcinogen
metabolism, DNA repair, and oxidative stress. In both age groups, the relationship
between endogenous exposure to organochlorines (PCBs, hexachlorobenzene,
dichlorodiphenyl dichloroethane), metals (cadmium, lead), and urinary metabo-
lites (1-hydroxypyrene,
trans
-
trans
muconic acid) vs. genotoxic effects (Comet
assay and micronuclei in lymphocytes, and urinary 8-hydroxydeoxyguanosine)
was investigated. In adults, the relationship of these exposures was tested using
selected tumor markers (prostate-speciic antigen, carcinoembryonic antigen, and
p 53). The impact of the genotype on established exposure-effect relationships
revealed eight exposure-effect relationships, and three novel associations that
affected various genotypes, predominantly those involving biotransformation and
oxidative stress responses. These techniques may also be applicable to evaluating
increased risk of cardiovascular events, metabolic conditions, and alterations in
cognitive functions.
3.1
Hazards Associated with Disposal in Landills
More than 220 papers have been published that address the health hazards associ-
ated with landill sites (Saffron et al.
2003
). Of these, 101 were primary studies that
concerned the health effects originating from landill sites, and 23 addressed the
health effects of drinking water contaminated with leachate from landill sites. Six
reviews addressed epidemiological evidence linking health effects with landill sites
(Cantor
1997
; Miller
1996
; Sever
1997
; Johnson
1997
, Vrijheid
2000
). However,
the source of contamination that caused human health effects in these studies was
not known. In some studies, the source was thought to be leaking chemical storage
tanks, and in others, chemical accidents. Study authors that investigated links
between landill sites and communities revealed the plethora of targeted effects that
were examined; these included reproductive or developmental effects on children
(31 studies), cancer (29 studies), clinical symptoms (28 studies), psychosocial
impacts (19 studies), biomarkers (13 studies), health problems not speciied (14
studies), mortality (5 studies), and injuries/poisoning (only 2 studies).
The weakness of studies that address the health effects of E-waste at landills is
the complete lack of exposure data. Rather than gathering exposure data at landill
sites, investigators used census data, postal codes, or other information that linked
the number of residents having proximity (2-3 km of the site) to the landill, as a
poor proxy for exposure. Because of the lack of exposure data, many studies gen-
erated more questions than answers. In addition, none of the hypothesis-testing
studies controlled for possible confounding factors. In residential areas, where
E-waste facilities sometimes exist, there are many other sources of pollution that
make it dificult to assign causality of disease to E-waste-connected activities.
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