1. Informed consent: Special populations may be more vulnerable to coercion or undue influence, making it difficult to obtain informed consent. For example, a child may not be able to understand the risks and benefits of research participation, or a person with a mental illness may feel pressured to participate in research because they believe it is the only way to get help.
2. Confidentiality: Special populations may have a greater need for confidentiality than other populations. For example, a person with a marginalized identity may be concerned about how their participation in research will affect their reputation or their ability to get services.

Here are some ethical dilemmas a researcher could face with these populations:

• Exploitation: Researchers may exploit special populations by using them for their own gain, without considering the potential risks or benefits to the participants. For example, a researcher may offer financial incentives to people with disabilities to participate in research, even if the research is not likely to benefit them.
• Beneficence: Researchers have a duty to do no harm to their participants. However, it can be difficult to balance the potential risks and benefits of research with special populations. For example, a researcher may want to conduct research on a new treatment for a serious mental illness, but the treatment may have unknown side effects that could harm the participants.
• Justice: Researchers have a duty to ensure that all participants are treated fairly. However, it can be difficult to ensure that special populations are not discriminated against in research. For example, a researcher may be more likely to recruit white participants for a study than black participants, even if the study is not about race.

The principles of ethical research that are involved in these dilemmas include:

• Respect for persons: This principle requires researchers to respect the autonomy of their participants and to obtain their informed consent.
• Beneficence: This principle requires researchers to do no harm to their participants and to maximize the potential benefits of research.
• Justice: This principle requires researchers to ensure that all participants are treated fairly.

To handle these dilemmas in planning research, it is important to carefully consider the potential risks and benefits of the research to the participants. Researchers should also take steps to protect the confidentiality of the participants and to ensure that they are not exploited. It is also important to get the input of experts in ethics and research with special populations when planning research.

Here is a peer-reviewed resource that supports my response:

• “Ethical Issues in Research with Special Populations” by the American Psychological Association. This article provides an overview of the ethical issues that researchers face when conducting research with special populations.