Cytogenetoxicity of University Teaching Hospital (UTH) wastewaters was
investigated using the
Allium cepa
assay. Heterogeneous samples of untreated wastewaters from
four sections of the hospital comprising the laboratories, mortuary, laundry and the kitchen were
collected twice daily for six months and designated as complex mixtures. Physico-chemical
parameters of the wastewaters were determined in accordance with standard methods. Onions
root growth inhibition test was used to assess the toxic status of the wastewaters, while
cytogenotoxicity was measured by microscopic investigation of the chromosomal aberrations.
Onion bulbs were exposed to 1%, 5%, 10% 25% and 50% concentrations of the effluent
samples in the dark for 72 hours before measuring the root lengths of the onion bulbs. Results of
BOD, COD, TSS and pH showed levels above the maximum permissible limits for discharge of
hospital effluent into the environment. There was inhibition of root growth of
A. cepa in a
concentration dependent pattern compared to control. An effective concentration EC
50 of 8.20%
and 9.1% was deduced for the 1
st and 2
nd samples respectively. Various morphological defects
of the onions roots were also observed. Cytological analysis of root tips after 48 hrs exposure to
the different concentrations showed reduction in frequency of mitosis in the meristematic zones
of the root tips. Various types of structural chromosomal aberrations and micronucleus were
induced in the treated cells. The University Teaching Hospital wastewaters samples are believed
to contain potent toxic substances that provoked the cytogenotoxic responses herein and should
be treated before discharge into the environment. ©JASEM
