The ethics of research involving animals - Nuffield Council on ...
The ethics of research involving animals - Nuffield Council on ...
The ethics of research involving animals - Nuffield Council on ...
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T h e e t h i c s o f r e s e a r c h i n v o l v i n g a n i m a l s<br />
required endpoint, or if it is the easiest endpoint to observe reliably, it may be used. In<br />
specific cases, the terminal stages <str<strong>on</strong>g>of</str<strong>on</strong>g> a lethal endpoint may not involve much, if any,<br />
suffering as the animal may be comatose. However, the suffering that may have taken place<br />
beforehand can be substantial and may involve c<strong>on</strong>siderable distress including loss <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
appetite, malaise, c<strong>on</strong>vulsi<strong>on</strong>s or imbalance rather than pain.<br />
Animal use in toxicity testing (Chapter 9)<br />
10.23 Tests <str<strong>on</strong>g>involving</str<strong>on</strong>g> <str<strong>on</strong>g>animals</str<strong>on</strong>g> play an important role in the safety assessment <str<strong>on</strong>g>of</str<strong>on</strong>g> compounds such<br />
as medicines, household chemicals, agrochemicals and industrial chemicals when brought<br />
into c<strong>on</strong>tact with humans, <str<strong>on</strong>g>animals</str<strong>on</strong>g> or the envir<strong>on</strong>ment. Chemicals are assessed for their<br />
potential to cause irritati<strong>on</strong>, physiological reacti<strong>on</strong>s, cancers, developmental<br />
complicati<strong>on</strong>s for foetuses in utero, and effects <strong>on</strong> fertility. Sixteen percent <str<strong>on</strong>g>of</str<strong>on</strong>g> the total<br />
number <str<strong>on</strong>g>of</str<strong>on</strong>g> procedures using <str<strong>on</strong>g>animals</str<strong>on</strong>g> in 2003 in the UK were c<strong>on</strong>ducted for the purpose<br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> ‘toxicology or safety evaluati<strong>on</strong>’. Specified doses and exposures <str<strong>on</strong>g>of</str<strong>on</strong>g> the chemicals are<br />
given to <str<strong>on</strong>g>animals</str<strong>on</strong>g>, from which informati<strong>on</strong> regarding safe human dose and exposure levels<br />
is then extrapolated.<br />
10.24 Rats and mice are most comm<strong>on</strong>ly used in toxicology (74 percent <str<strong>on</strong>g>of</str<strong>on</strong>g> procedures). Other<br />
tests involve n<strong>on</strong>-rodent species such as fish, rabbits, chickens, dogs and primates. Tests<br />
range from <strong>on</strong>e single high dose to l<strong>on</strong>g-term exposure to a particular chemical, in order<br />
to observe the effects seen when a product is used (or misused) in different situati<strong>on</strong>s. <str<strong>on</strong>g>The</str<strong>on</strong>g><br />
tests are designed to mimic the possible routes <str<strong>on</strong>g>of</str<strong>on</strong>g> exposure that humans might be<br />
subjected to, such as through the mouth, skin, eyes or airways. <str<strong>on</strong>g>The</str<strong>on</strong>g> informati<strong>on</strong> produced<br />
is used mainly to ascribe chemicals to bands <str<strong>on</strong>g>of</str<strong>on</strong>g> acute toxic effects, which restricts how they<br />
may be used. Regulatory requirements demand that the studies are c<strong>on</strong>ducted in a way<br />
that minimises the numbers <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>animals</str<strong>on</strong>g> used and which reduces pain and distress as far as<br />
possible (paragraphs 9.4 and 13.17).<br />
10.25 Toxicity testing has a range <str<strong>on</strong>g>of</str<strong>on</strong>g> welfare implicati<strong>on</strong>s for test <str<strong>on</strong>g>animals</str<strong>on</strong>g>, some <str<strong>on</strong>g>of</str<strong>on</strong>g> which can be<br />
severe. <str<strong>on</strong>g>The</str<strong>on</strong>g>se effects are minimised by the ‘build-up’ approach in which severe reacti<strong>on</strong>s<br />
can be detected at an early stage (acute toxicity followed by chr<strong>on</strong>ic toxicity, paragraph<br />
9.14). More recently alternative methods have been developed which, when utilised<br />
during the early stages <str<strong>on</strong>g>of</str<strong>on</strong>g> testing, may prevent very toxic substances from being<br />
administered to <str<strong>on</strong>g>animals</str<strong>on</strong>g>. For example, studies that evaluate irritant potential to the skin<br />
or eye are preceded by tests that use in vitro human or animal tissue to identify chemicals<br />
with the potential to cause severe irritati<strong>on</strong> or corrosi<strong>on</strong>. <str<strong>on</strong>g>The</str<strong>on</strong>g>se tests are termed ‘n<strong>on</strong>animal<br />
pre-screens’. However, it is an intrinsic part <str<strong>on</strong>g>of</str<strong>on</strong>g> most toxicity tests to cause some<br />
form <str<strong>on</strong>g>of</str<strong>on</strong>g> harm to <str<strong>on</strong>g>animals</str<strong>on</strong>g>.<br />
10.26 A full complement <str<strong>on</strong>g>of</str<strong>on</strong>g> toxicity tests can entail the use <str<strong>on</strong>g>of</str<strong>on</strong>g> between 1,500 and 3,000 <str<strong>on</strong>g>animals</str<strong>on</strong>g>,<br />
although not all <str<strong>on</strong>g>of</str<strong>on</strong>g> these will suffer the most harmful c<strong>on</strong>sequences <str<strong>on</strong>g>of</str<strong>on</strong>g> the testing. <str<strong>on</strong>g>The</str<strong>on</strong>g><br />
adverse effects range from minor changes such as reduced weight gain to severe effects<br />
including loss <str<strong>on</strong>g>of</str<strong>on</strong>g> organ functi<strong>on</strong>, leading to death (paragraphs 9.32-9.37). Certain methods<br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> reducti<strong>on</strong> and refinement are relevant to toxicology, but progress has been difficult<br />
(paragraphs 9.3-9.4).<br />
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