May 18, 2007
Environmental Exposure Assessment, Pollution Sources, and Exposure Agents: A Primer for Pediatric Nursing Professionals
By Shendell, Derek G; Pike-Paris, Ann
Children's environmental health is a growing, interdisciplinary field of diverse professionals and community members working together in policy advocacy, research, health, and environmental interventions and treatment services. Understanding exposure assessment is central to improving children's health across age, gender, indicators of socioeconomic status, and racial/ethnic groups. In general, children are more susceptible and vulnerable to adverse acute and chronic effects due to acute and chronic exposures to environmental toxicants since they eat more food, drink more fluids, and breathe in more air per unit of body weight than adults; their behaviors and rapid developmental changes also contribute to their risks. By enhancing knowledge and awareness of the basic concepts of human exposure assessment and key details of sources of environmental pollution, pediatric nursing professionals can enhance their practices - clinical and patient education skills - and thus improve daily work in their communities through the promotion of exposure reduction or prevention measures.
Environmental Pollution (Hazards or Agents)
The informative statements and specific illustrative examples presented in this section and throughout this article are typical of the information found in environmental health textbooks; state, and federal, public health and environment agencies websites; and, peer- reviewed journal articles in scientific disciplines directly or indirectly related to environmental health. For a list of some suggested readings for pediatric nurses to acquire further background knowledge than presented below, please refer to the list at the end of this article (e.g., Etzel & Balk, 1999, 2003; Schneider & Freeman, 2000; Frumkin, 2005; NEETF, 2006, USEPA, 2006a).
Data. Typically, two different kinds of information are discussed related to environmental pollution: hazard data and source data. Hazard data refers to the amount of a pollutant released into the environment or to which a population is at risk of being exposed such as the concentration of a contaminant in outdoor air or water. This information is most useful for risk assessment or epidemiological research because it approximates the amount of the substance in the environment regardless of where it came from. Source data is tied to an activity or facility releasing one or more substances into the environment. These data are usually expressed as pounds or tons emitted. Source data do not supply the pollutant concentration in an environmental media, so these cannot be used to quantify health risk directly. Nevertheless, knowledge of where pollutants come from is often the first step towards mitigation.
Sources and media. Two major categories of sources of environmental pollution are:
1. Natural - for example, pollen or re-suspended dust from unpaved roads; and,
2. Human-made, or anthropogenic - for example, industry, cars, trucks, oil refineries. The majority of pollution sources of present public health concern are human-made.
Sources of pollution can release one or more pollutants into our environment to one or more media. This can occur one at a time or in mixtures well-defined or poorly defined.
Four major categories of pollutants, or hazards or environmental exposure agents, are:
1. Chemical agents - those made with carbon and hydrogen (organic compounds), with or without metals, and those made without carbon but with nitrogen, sulfur, hydrogen, oxygen, metals, etc;
2. Biological agents - pollen, bacteria, and mold (fungi, mildew, spores);
3. Physical agents - noise (loudness, measured as Aweighted decibels, and frequency related to people being annoyed), light, vibration, force (due to weight, twisting, bending), stress, and variables related to climate like temperature, relative humidity, and wind; and,
4. Radioactive agents - example, radon gas, electromagnetic fields, and waste products from the generation of nuclear energy and production of nuclear weapons.
Five major categories of environmental media are:
1. Air, outdoors and indoors (which is influenced by indoor and outdoor sources);
2. Water, including surface waters like rivers (think recreation and travel) and reservoirs (drinking water treatment plant process sources), groundwater aquifers (think wells);
5. Biota, like fish used for food (which build-up certain pollutants in their fatty tissue).
Case Example: Air Pollution Categories and Pollution Source Categories
Outdoor and indoor air pollutants are generally spoken of in two categories: criteria and hazardous air pollutants. Criteria air pollutants are the six outdoor air pollutants subject to federal laws (USEPA, 2007) and/or state laws if those are more stringent (e.g., California Air Resources Board, 2006). These laws require health-based outdoor air concentrations not exceed a certain level. Hazardous air pollutants, on the other hand, are other chemicals known or suspected to cause several adverse health outcomes, including cancer (USEPA, 2006b).
Sources of air pollutants are categorized as follows:
1. Point sources - individual industrial facilities (think smoke stacks), for example, power plants, oil refineries, and cement factories.
2. Area sources - sources present over a defined geographic area, for example, a petrochemical facility (making and/or using many chemicals), architectural coatings composed of chemical-based solvents, consumer products (like dry cleaners), and agriculture (pesticides and re-suspended soil dust particles). The concept is known quantities of pollutants may be released within a defined area, but exactly where pollutants are produced can be difficult to identify.
3. Mobile sources - moving vehicles, such as cars, trucks, trains and planes.
There are two sub-categories of mobile sources:
* "On-road" mobile sources include cars, vans, sport utility vehicles (SUVs), pick-up trucks and buses (usually using gasoline or diesel fuel), and heavy-duty diesel trucks. It is important to note an entire highway may be called a "mobile line source."
* "Off-road" mobile sources include trains, ocean and river- going ships, planes, farm equipment, construction equipment, and road maintenance equipment (including street cleaning vehicles), each of which usually uses diesel fuel.
Understanding Source (Emissions) vs. Hazard Data (Concentrations in Media like Air)
Source data are considered to be emissions, whereas hazard data are the concentrations in media like air, water, etc. It is possible, for example, to measure the amount of particles in the outdoor air over a day and compare the data to federal and state ambient air quality standards. It is rare to have both source and hazard information at the same time. Determining what are the major contributors and then each individual, relative contribution to measured data is the issue. Following our example, particles usually have many sources, which then determine particle size and composition. As a result, it is difficult to use these types of data as indicators of potential community exposure and associated health problems.
Environmental data can help characterize exposed populations, potential avenues for remediation, or both. Monitoring concentrations of pollutants having multiple sources usually does not suggest a remediation strategy, while monitoring sources of pollutants usually does. To the non-environmental scientist or engineer, such as a health care provider, it can be confusing \to read scientific papers and government reports about pollution, in print or on the Internet, due to unfamiliar terms. For instance, sometimes "source emissions" will be used rather than "pollutant emissions" or "hazards" into the air, water, soil, etc. Perhaps an article will focus on "truck counts,""traffic counts," and "distances between homes and freeways or hazardous waste sites," without describing what the actual exposure agent may be, what form it is in, and whether it is safely or improperly stored. Simply stated, sometimes a source is written about or spoken of as though it were an environmental hazard (pollutant). In these cases, the source (truck, traffic, hazardous waste site) is used as an indicator of the actual pollutants released into the environment. Therefore, it is important to distinguish concentrations or levels of a pollutant or mixture of pollutants measured in an environmental media in a particular place after being released by a source or sources, and actual human exposure.
To understand someone's exposure, we must look at how exposure occurs and how the prevention or reduction of exposure can lead to community (public) health benefits. Measured concentrations may range from low to high, relative to health-based laws or guidelines, and may represent a particular place (home, school, office) or a larger geographical area (city, county). One drawback is concentrations in environmental media are not true measures of individual or population exposure. When exposure to pollutants does occur, we then become concerned about risks of adverse acute and chronic health outcomes. Exposures may also reflect disparities among racial/ethnic and lower versus higher income sub-populations.
Understanding exposure assessment definitions. Exposure requires contact between a target and one or more agents, in one or more environmental media, by one or more defined pathways, at one time or over a period of time.
Target = an adult, an adolescent, a child, an toddler, an infant, a fetus;
Agents = a hazard/pollutant (chemical, biological, physical, radiological);
Media = air, water, soil, floor/surface dust indoors, particles in air, food like fish (pollutants can bioaccumulate in fatty tissue), body fluids (like blood, saliva, urine);
Pathways = inhalation (breathing in through the nose or mouth), dermal (on and/or through the skin), ingestion (eating food, drinking liquids) including breastfeeding an infant; transplacental (mother to fetus via blood along with oxygen, nutrients, etc);
Acute exposure = one time;
Chronic exposure = over a period of time, described by one of the following terms:
* Continuous = a similar exposure repeated over time - for example, people are continuously exposed to any drinking water pollutant (low-level) or workers are continuously exposed to specific chemicals in the workplace;
* Intermittent = an exposure, small or large, occurs more than once over a period of time at defined intervals - for example, combustion-related pollution from a locomotive which passes by on tracks adjacent to homes four times a day;
* Episodic = an exposure, typically large, which occurs more than once over a long period of time but at unknown intervals - for example, dust particles and chemical pollutants released during building demolitions or large fires.
Understanding Exposure versus Dose. Exposure to an environmental hazard (pollutant), whether at low or high concentrations, does not always result in an adverse health outcome. The health outcome of interest, whether acute or chronic in nature, depends upon several factors determining dose. As a simple yet illustrative example, though human life depends upon clean, purified drinking water, too little or too much of it may lead to dehydration or a significant electrolyte imbalance, respectively. Both could lead to death if not treated in an appropriate, timely manner.
Dose can be defined as a composite of:
* Frequency and duration of the exposure, including if exposure is acute or chronic;
* Quantity, the pollutant concentration in an environmental media at the time of human contact; and,
* Individual susceptibility factors, such as gender, age, genetics, existing health conditions, race/ethnicity, socioeconomic factors, and/or presence of allergy.
For example, asthma attacks among school-aged children may be caused by acute and chronic exposure to environmental asthma triggers. These exposures lead to smaller or larger doses. A child's outcome is then also determined by multiple variables like age, gender, race, and health status, including whether someone is allergic and/or if they use prescribed controller medications at home each morning or evening. Therefore, the frequency and severity of asthma attacks and related symptoms relate to exposure and dose.
How to Potentially Act
One goal of public health is to help reduce or prevent exposure by understanding, identifying, and mitigating sources of environmental pollution. To help achieve community health goals, pediatric nursing professionals can help educate the public, that is, patients and their families and caregivers, and as appropriate be informed advocates for policy change and regulatory monitoring and enforcement. For example, individuals can eliminate or substitute sources of pollution with non-toxic or less toxic alternatives to consumer products used for personal care, cleaning, hobbies and pest control etc in homes, schools, day care, parks and playgrounds etc to reduce exposure (e.g., CHEC, 2007). As another example, individuals can work towards implementation of cost- effective integrated pest management in homes, schools, day care, parks and playgrounds, etc using non-toxic or least-toxic alternatives to the chemical pesticides normally used (e.g., Beyond Pesticides, 2007). Sources and exposure agents would be identified through a pediatric environmental history taking process (NEETF, 2006) or a pediatric environmental health assessment conducted during a home visit (NCHH, 2007). Promoting primary prevention and precautionary actions comprises one of the many responsibilities of pediatric nurses. Limiting exposure, dose, risk, and thus subsequent adverse acute and chronic health outcomes - injuries, illness and associated symptoms, disability or death - is crucial. Protecting one of our most sensitive and precious population groups, children, is essential.
The Environmental Health Hot Topics column focuses on issues, information, and practical guidelines related to environmental health problems, including sources of toxicants and resources for nurses to prevent, minimize, or treat adverse environmental exposures particularly as they relate to children. To suggest topics, obtain author guidelines, or to submit queries or manuscripts, contact Ann Pike-Paris, MS, RN, Section Editor; Pediatric Nursing, East Holly Avenue Box 56; Pitman, NJ 08071-0056; (856) 256-2300 or FAX (856) 256-2345.
Note: For further reading, pediatric nursing professionals can consult many references in print and on the Internet, including these selected comprehensive books and websites within the alphabetized list below. They are available at no cost or relatively low-cost to purchase and/or access through local public and university libraries. We also list the selected journal papers referenced in this article as well as some new continuing training opportunities.
Bearer, C.F. (1995). How are children different from adults? Environmental Health Perspectives, 103(Suppl 6), 7-12.
Bearer, C.F. (2000). The special and unique vulnerability of children to environmental hazards. Neurotoxicology, 21(6), 925-934.
Beyond Pesticides. (2007). Center for community pesticide and alternatives information. Retrieved February 19, 2007, from http:// www.beyondpesticides.org/ccpai/index.htm
California Air Resources Board. (2006). Ambient air quality standards chart (California and Federal). Retrieved November 28, 2006, from http://www.arb.ca.gov/aqs/aaqs2.pdf
Children's Environmental Health Network (CEHN). (2006). Guiding principles for children and environmental health. Retrieved November 28, 2006, from http://www.cehn.org/
Children's Health Environmental Coalition (CHEC). (2007). Safer products store. Retrieved February 19, 2007 from, http:// www.checnet.org/safer_products.asp
Cohen Hubal, E.A., Sheldon, L.S., Burke, J.M., McCurdy ,T.R., Berry, M.R., Rigas, M.L., Zartarian, V.G., &N Freeman, N.C. (2000). Children's exposure assessment: A review of factors influencing children's exposure, and the data available to characterize and assess that exposure. Environmental Health Perspectives, 108(6), 475- 488.
Etzel, R.A., & Balk, S.J. (Editors for American Academy of Pediatrics (AAP) Committee on Environmental Health). (1999, 2003). Pediatric Environmental Health (1st and 2nd editions, respectively). Elk Grove Village, IL: AAP.
Frumkin, H. (Editor). (2005). Environmental health: From global to local. San Francisco, CA: Jossey-Bass (A Wiley Imprint).
Golub, M.S. (2000). Adolescent health and the environment. Environmental Health Perspectives, 108(4), 355-362.
Healthy Schools Network. (2006). The healthy schools/healthy kids clearinghouse: Guides and reports. Retrieved November 28, 2006 from, http://www.healthyschools.org/guides_materials. html
Landrigan, P.J, Carlson, J.E., Bearer, C.F., Cranmer, J.S., Bullard, R.D., Etzel, R.A, Groopman, J., McLachlan, J.A., Perera, F.P., Reigart, J.R., Robison, L., Schell, L., & Suk, W.A. (1998). Children's health and the environment: A new agenda for prevention research. Environmental Health Perspectives, 106(Suppl 3), 787-794.
Landrigan, P.J. (2004). Children as a vulnerable population. International Journal of Occupational Medicine and Environmental Health, 17(1), 175-177.
National Environmental Education and Training Foundation (NEETF). (2006). Pediatric environmental history initiative. Retrieved November 28, 2006 from, http://www.neetf.org/Heal\th/PEHI/
National Center for Healthy Housing (NCHH). (2007). Pediatric environmental home assessment on-line training for public health and visiting nurses. Retrieved February 9, 2007 from, http:// www.healthyhomestraining.org/Nurse/PEHA_Start.htm
Rosenstock, L.S., & Cullen, M. (Editors). (1994). Textbook of clinical occupational and environmental medicine (1st edition). Philadelphia: W.B. Saunders and Company.
Rosenstock, L.S., & Cullen, M. (Editors). (2005). Textbook of clinical occupational and environmental medicine (2nd edition). Philadelphia: W.B. Saunders and Company.
Schneider, D., & Freeman, N. (2000). Children's environmental health: Reducing risk in a dangerous world. Washington, DC: American Public Health Association.
Shendell, D.G., Barnett, C., & Boese, S. (2004). Science-based recommendations to prevent or reduce potential exposures to biological, chemical, and physical agents in schools. Journal of School Health, 74(10): 390-396.
United States Environmental Protection Agency (USEPA). (2006a). Children's health protection. Retrieved November 28, 2006 from, http://yosemite.epa.gov/ochp/ochpweb.nsf/content/homepage.htm
USEPA. (2006b). Hazardous air pollutants.. Retrieved November 28, 2006 from, http://www.epa.gov/ebtpages/ airairpohazardousairpollutantshaps. html
USEPA. (2007). National ambient air quality standards. Retrieved February 19, 2007 from, http://www.epa.gov/air/criteria.html.
University of Maryland School of Nursing. (2006). Post-master's certificate program in environmental health. Retrieved November 28, 2006 from, http://nursing.umaryland.edu/programs/online/ environmental.htm
Ann Pike-Paris, MS, RN
Derek G. Shendell, D.Env, MPH, is Assistant Professor, Environmental Public Health Sciences, Institute of Public Health, Georgia State University, Atlanta, GA.
Ann Pike-Paris, MS, RN, is Consultant, Clinical Support Services, Hayes, Inc., Buffalo, NY. She is also a member of the Pediatric Nursing Editorial Board.
Copyright Anthony J. Jannetti, Inc. Mar/Apr 2007
(c) 2007 Pediatric Nursing. Provided by ProQuest Information and Learning. All rights Reserved.