Introduction

Most environmental and occupational diseases either manifest as common medical problems or have nonspecific symptoms. Unfortunately, hazardous exposures rarely enter into the clinician's differential diagnosis. As a result, clinicians may miss the opportunity to make correct diagnoses that might influence the course of disease. A correct diagnosis may help stop exposure and might prevent disease in others by avoiding exposure [ATSDR 2015].

What can a clinician do to improve recognition of disease related to current or past exposures?

• First, one must be suspicious and think about the possibility of environmental and occupational factors of disease.
• Next, one needs to incorporate an exposure history questionnaire into clinical practice.

ATSDR Case Study in Environmental Medicine: Taking an Exposure History

https://www.atsdr.cdc.gov/csem/csem.asp?csem=33&po=0

illustrates the principles and practices involved in the development of a differential diagnosis that includes possible hazardous exposure related etiologies.

Taking an exposure history may enable physicians to

• Make more accurate diagnoses,
• Influence the course of disease by stopping current exposure,
• Prevent disease in others by avoiding future exposure, and
• Prompt workplace evaluations and the protection of workers.

In the past, the Centers for Disease Control and Prevention (CDC) emphasized primary prevention, but also recommended screening blood lead levels (BLLs) in children to alert policymakers and others of potential lead contamination in communities.

Generally, sources of lead exposure were only identified and remediated after a child was identified with an elevated BLL, which is now a practice considered ineffective [ACCLPP 2012].

The strategy of identifying lead poisoning or elevated blood lead levels (BLLs) relied on detection in the child, relegating the child to the function of the proverbial 'canary in the coal mine' for

• Poor/contaminated housing,
• Contaminated water, and/or
• Tainted consumer products.

This strategy, which relies on identifying extant elevated BLLs, does not prevent the damage already incurred. Chelating agents can be used to treat overt lead poisoning, and possibly reduce the case fatality rate and other severe effects. However, chelating agents are not benign and can cause adverse health effects, especially when used by someone without expertise and experience treating lead poisoned patients. These agents have been demonstrated not to improve IQ or behavioral consequences of lead exposure [ACCLPP 2012]. Therefore, primary prevention is the most important and significant strategy [ACCLPP 2012].

The first step in evaluating a possibly lead-related health concern in a child is to take an environmental pediatric exposure history.

Screen all immigrant, refugee, and internationally-adopted children when they arrive in the United States, and for children <6 years old again 6 months after resettlement.

Screening Questions

The clinical setting allows little time for an extensive environmental pediatric exposure history. However, initial and subsequent well-child visits offer opportunities to provide parents and caregivers with educational materials on preventing exposures and actions to take if an exposure occurs. CDC [2012] recommends using screening questions.

Written checklists completed by parents may be used to facilitate obtaining an exposure history. Examples of these checklists are the National Environmental Education Foundation's [NEEF] Pediatric Environmental History (0-18 Years of Age). The Screening Environmental History, and Additional Categories and Questions to Supplement The Screening Environmental History, 2005. Also available in Spanish.

https://www.neefusa.org/resource/pediatric-environmental-history

ATSDR Case Study in Environmental History: Taking a Pediatric Exposure History

https://www.atsdr.cdc.gov/csem/csem.asp?csem=26&po=0

For a sick child whose illness might be environmentally related, the physician should consider an environmental agent as potentially related to the child's current illness, particularly when the illness does not follow a usual pattern or when more than one family member or a schoolmate is affected.

Physicians should take two environmental medicine actions for every well-child who presents to an office or a clinic.

1. A routine screening history for potential environmental exposures.
2. Age-appropriate risk-based screening for lead poisoning, using the CDC's lead poisoning prevention guidelines [CDC 2012].

Table 5. Screening Questions for Children's Lead Exposure History [modified from ATSDR 2013]

Sick Child Visit Temporal Relationship

In order to establish that lead exposure is the cause of an illness, it is necessary to ask if the exposure to the substance of concern occurred before the onset of the health condition.

Timing and duration of exposure can be important in determining whether a negative health effect may result. If the exposure is known, it is important to ask how long and how often the child was exposed to lead (daily, weekly, monthly, etc.). It is also important to ask about the amount or concentration (how much).

Sick Child Visit -Are Other Affected?

Others similarly affected can point to a possible lead exposure-related cause at home, at child care, at school, or the workplace. For public health reporting purposes, the appropriate authorities must be notified if an illness is found to be related to a lead environmental exposure

Sick Child Visit Linking Exposure to Illness

After completing the screening exposure history and asking more specific exposure-related questions, the physician should then answer these questions to determine whether the illness might be lead exposure-related.

• What is the child's specific health condition?
• Is lead known to cause this type of health problem?
• If so, what is the weight of scientific evidence linking that health condition to lead?
• Did any other exposures occur that might be related to the identified signs and symptoms?

If the answers to these questions, previous questions and the physical and laboratory findings point to a link between an illness and an exposure, the physician can consult with a specialist in pediatric environmental medicine as needed (see http://www.pehsu.net/).

Progress Check