<?xml version="1.0" encoding='utf-8'?>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" "http://www.wapforum.org/DTD/wml_1.1.xml">
<wml>
<card id="card1" title="Natural experiment - Page 13 - Wikipedia">
<p>
<a accesskey="1" href="page.php?w=natural_experiment&amp;p=12">1.Previous</a><br />
<a accesskey="3" href="page.php?w=natural_experiment&amp;p=14">3.Next</a>
</p>
<p>into the atmosphere, some of which could be incorporated into biological tissues. The release stopped after the <a href="page.php?w=Partial_Nuclear_Test_Ban_Treaty">Partial Nuclear Test Ban Treaty</a> in 1963, which prohibited atmospheric nuclear tests. This resembled a large-scale <a href="page.php?w=pulse-chase_experiment">pulse-chase experiment</a>, but could not have been performed as a regular experiment in humans due to scientific ethics. Several types of observations were made possible (in people born before 1963), such as determination</p><p>
<a accesskey="1" href="page.php?w=natural_experiment&amp;p=12">1.Previous</a><br />
<a accesskey="3" href="page.php?w=natural_experiment&amp;p=14">3.Next</a>
</p>

<do type="prev" label="Search">
        <go href="search.wml"/>
</do>

</card>
</wml>
