Page 366 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

Ionizing Radiation in Veterinary Medicine Chapter | 19 333

VetBooks.ir (Darby et al., 2010) and cataracts (Worgul et al., 2007). tanks (Berger et al., 1987). If a water source appears to be
grossly contaminated, which is common following any
More than 30 years after the 1986 Chernobyl NPP acci-
natural or man-made disaster, boiling or chlorination may
dent in Ukraine, very little is known about the current
health status of mammalian species within the Chernobyl be helpful but will not remove all contaminants, including
Exclusion Zone (CEZ). Following the Chernobyl acci- radiation.
dent, reproductive effects were noted in carp from a fish Use of uncontaminated animal feed is best. However,
farm established in the power plant’s cooling pond when this is not possible, at least initially, potentially con-
(Belova et al., 1993; Makeeva et al., 1994). Genetic taminated outer layers of hay bales and feed piles should
effects have been seen in barn swallows breeding near be carefully removed and set aside to allow time for
Chernobyl, along with an increased frequency of albinism radioactive decay. To reduce the possibility of radioiodine
(Ellegren et al., 1997; Moller et al., 2007; Bonisoli- contamination of milk, this retention time should be at
Alquati et al., 2009). Additional studies document nega- least 40 days for dairy cattle (Berger et al., 1987). Closed
tive impacts on plant and animal life (Geras’kin et al., bags or barrels of feed should be carefully handled and
2008) and substantial accumulations of radionuclides in decontaminated when necessary to prevent contamination
wildlife (Chester et al., 2001). Recent data suggest that of the feed inside.
wildlife populations are not depleted within even the most
137 2
Cs-contaminated areas of the 4300 km CEZ (Webster
et al., 2016). However, further studies are needed. In ani- Prophylaxis
mals that appear to be the least sensitive to radiation,
insects and soil invertebrates, levels of chronic exposure Internal contamination with radionuclides persists until
producing effects vary from 2 to 1000 mGy per day they either decay or are eliminated. This, and therefore
(Wood et al., 2005). Chronic exposures of up to 192 mGy the management of internally contaminated patients, is
per day of gamma radiation produced no adverse effects isotope dependent. Interventions can be useful, however
in terrestrial isopods (Hingston et al., 2005). are only available for a few specific isotopes. For beta
emitter 131 I that was associated with increased risk of
childhood thyroid cancers following Chernobyl, the half-
MITIGATING ACUTE RADIATION life of only 8 days is relatively short compared to those
EXPOSURES IN ANIMALS for 134 Cs and 137 Cs, which are instead 2 years and 31
years, respectively. Potassium iodide (KI) can be used
Minimizing Exposure 131
prophylactically to reduce thyroid uptake of I if taken
Following the Chernobyl disaster, the maximum expo- within 4 hours of the incident. Oral potassium iodide has
sures to animals and plants occurred within the first been used in veterinary medicine as an extra-label treat-
10 20 days, with the main contributors being the short- ment for sporotrichosis (Plumb, 2015). It should be noted
lived radionuclides (Alexakhin and Geras’kin, 2011). For that iodides are excreted in milk.
people responding to radiological incidents, exposures are Clay minerals (bentonites, vermiculites, zeolites) can
minimized by isolating them from potential sources using be used to reduce animals’ absorption of radiocesium
personal protective equipment (PPE), including respirators and its subsequent transfer to food products (Howard
and goggles. Strategies to consider for animals postinci- et al., 2001). Prussian blue (ferric hexacyanoferrate)
dent should include confining either the source or the ani- enhances fecal cesium excretion (Yamamoto, 2013).
mals, preventing or minimizing uptake, reducing uptake, Oral Prussian blue has been shown to be relatively non-
or increasing excretion. toxic in dogs, though it is most effective when given
Animals left outside should be washed before bringing within 1 day of cesium intake (Melo et al., 2014).
them inside. Any structure will provide some shielding Several forms of ferrocyn were used after the Chernobyl
against sources of radiation outside. Controlling access to accident to reduce radiocesium transfer to meat and milk
contaminated food and water and providing clean or at (Ratnikov et al., 1998).
least less-contaminated sources to confined animals may Calcium and zinc DTPA (diethylenetriamine pentaa-
be an important first step that can be accomplished by cetic acid) form stable, urine-excretable complexes with
either first responders on scene, owners, or caretakers plutonium, americium, and curium (Yamamoto, 2013).
who are sheltered in place or returned following the inci- While treatment typically involves intravenous infusions
dent, though depending on the scope of the incident and (Singh et al., 2015), studies using an oral form of zinc
the number of animals involved this may be difficult to DTPA dogs and rats have demonstrated low toxicity,
accomplish in a timely manner or at all. Water from wells with a no-observed-adverse-effect level of approximately
and covered tanks are least likely to be contaminated fol- 1325 mg/kg/day in dogs and .1000 mg/kg/day in rats
lowing an incident compared to water in ponds and open (Shankar et al., 2014).