Page 170 - Soil Degradation, Conservation and Remediation

6.2 Sources of Soil Pollutants 159

the active thermophilic degradation period could induce degradation of pesticide
contaminants. In the review of pesticide occurrence and degradation during
composting, Buyuksonmez et al. ( 1999 ) found that a few of the targeted pesticides
were found in the composts with organochlorine compounds being the most resistant
to degradation during composting.
Some herbicides are resistant to degradation. Clopyralid and picloram had been
detected in some compost (Bezdicek et al. 2001 ). Compost contaminated with
clopyralid, a broadleaf herbicide, caused plant damage in Washington State in 1999,
even though the damage largely disappears if the use of contaminated clippings as
feedstock is delayed for a year or longer (Miltner et al. 2003 ). Residues from other
broadleaf herbicides for lawn care, 2,4-D (2,4-dichlorophenoxy acetic acid), dicamba
(2-methoxy-3,6-dichlorobenzoic acid), and MCPP [2-(4-chloro-2- methylphenoxy
propionic acid)], were detected and found toxic to tomato ( Lycopersium esculentum
L.) (Bugbee and Saraceno 1994 ). Other pesticides that have also been detected in
composts include atrazine, carbaryl, and chlordane. While diazinon [ O , O -diethyl
( O -2-isopropyl-6-methyl-4-pyrimidinyl)] insecticide was used extensively for insect
control on turfgrass, its biodegradability is evident as only a trace of it (<1 %) could
be found after composting (Michel et al. 1997 ). Close to 11 % of the insecticide was
degraded during composting, and a majority of the insecticide was converted to a
potentially leachable but less toxic hydrolyzed product. The release of diazinon
through volatilization is extremely small (<0.2 %).

6.2.4 Hospital Wastes

A huge quantity of waste is generated in health-care facilities. These wastes include
general wastes, sharps, non-sharps, blood, body parts, chemicals, pharmaceuticals,
medical devices, and radioactive materials. Potentially infectious waste includes
all waste items that are contaminated with or suspected of being contaminated

with body fluids. Examples include blood and blood products, used catheters and
gloves, cultures and stocks of infectious agents, waste from dialysis and dentistry
units, waste from isolation units, wound dressings, nappies, discarded diagnostic
samples, and contaminated materials (swabs, bandages, and gauze) and equipment
(disposable medical devices). Wastes containing chemical substances such as laboratory
chemicals, empty bottles of lab or pharmacy chemicals, disinfectants that have
expired or are no longer needed, solvents, diagnostic kits, poisonous and corrosive
materials, and cleaning agents. Genotoxic waste consists of highly hazardous,
mutagenic, teratogenic, or carcinogenic waste containing substances with genotoxic
properties. Radioactive hospital wastes include unused liquids from radiotherapy or
laboratory research; contaminated glassware, packages, or absorbent paper; urine
and excreta from patients treated or tested with radioactive substances. These wastes
are often disposed with municipal wastes in open dumps and on lands.