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OMB # 0925-0746
Expiration Date: 08/31/2019

Level of Concern Categories Study

Researchers at the National Toxicology Program (NTP) want to better communicate conclusions about whether environmental substances can cause adverse health effects in people. This important study aims to update NTP’s Level of Concern (LoC) scale to better inform and protect public health.

If you would like more information on the study, please follow the links below.


Introductory Video

Please watch the below video to learn more about the Level of Concern Study.

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Study Overview

NTP uses the level of concern (LoC) framework to communicate its assessment of the degree of concern regarding the potential human health effects of selected substances given what is known about their toxicity, level of human exposure, and pharmacokinetics. As part of its systematic review methodologies, NTP is updating its LoC framework to enhance transparency in what the LoC categories mean, describing the factors considered in reaching conclusions and identifying strategies for improving their use as a risk communication tool.

This study will use expert solicitation from five NTP stakeholder sectors (academia, industry, non-government organizations, and federal and state agencies) to aid in determining the optimal number of LoC categories for an updated LoC framework. Participants will be randomly selected across these sectors from all registrants. Selected and not selected registrants will be notified shortly after registration closes.

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Participant Tasks

NTP has developed hypothetical LoC hazard scenarios (LoC cards) with each presented in a standard format on an electronic “card”. Each LoC card includes information about toxicity, level of exposure, and other details (e.g., pharmacokinetic information) and asks a question regarding the perceived LoC for health effects for a specific population group. Participants will review the information in each LoC scenario and carry out LoC card sorting exercises. Participants will use a web-based application with a user interface (“web-based instrument”) for the LoC card sorting exercises.

NTP hosts the web-based instrument on a secure, password-protected website. Each participant will use a unique username and password for accessing the website. Participants will be trained to use the tool and work independently. Participants will be able to access the website remotely at any time during the experimental LoC card sorting activity using a variety of Internet browsers. Information collection of participants’ responses will be automated and secure, and stored on NIEHS servers. Responses are confidential and will not be shared among participants.

There are two parts to each phase (i.e., Phase 1 A and B; Phase 2 C and D). It is estimated that participants will spend approximately 90 minutes to complete each part of the Phase.

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Eligibility Criteria

Participants must have:

  • M.S., Ph.D., M.D., or equivalent degree
  • At least 3 years of experience working in toxicology, epidemiology, risk assessment or a related field

Eligible participants will be men or women who have a M.S., Ph.D., M.D., or equivalent degree and at least 3 years documented employment working in public health or a risk assessment-related field, such as developing hazard identification conclusions based on human and/or animal data or conducting qualitative or quantitative characterizations of risk. Participants must not have seen, read, or discussed study materials (e.g., LoC cards) associated with this research project prior to beginning the study.

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Reporting Burden

Public reporting burden for this collection of information is estimated to average 90 minutes, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. It is estimated to take an additional 6 minutes to review the Study Form of Consent during registration.

An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid OMB control number. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to:

NIH, Project Clearance Branch
6705 Rockledge Drive, MSC 7974
Bethesda, MD 20892-7974
ATTN: PRA (0925-0746).
Do not return the completed form to this address.

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