1. Oxygen plays a key role in metabolism, but can also be an unhealthful agent. �������³´�л�������Źؼ����ã���Ҳ�������������ء�
2. For example, fats in some foods like fish and nuts are considered good for human health. Unhealthful fats include saturated and trans fats. ������˵��ijЩʳ�����ͺ��ң����е�֬������Ϊ�Ƕ����彡�������ġ��������ڽ�����֬����������֬����ת��֬����
3. SPECIAL REQUIREMENTS: Must be able to work safely in an environment requiring exposure to biological conditions that may be unhealthful or hazardous. ����Ҫ��U��������������¶�ڲ����������к����������������°�ȫ�Ĺ�����
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adj.
1. not sanitary or healthful
2. detrimental to good health
3. detrimental to health