Toxicology FAQ

What is the goal of the Toxicology module?

The goal is to make a useful decision-support application that accurately maps the knowledge domain of occupational toxicology.

What do you mean by “mapping” information?

Mapping means collecting the best information and placing it in the context of the whole map. With a map, the user can zoom in from the big picture to the details.

What is the process of making and maintaining the Toxicology module?

The detailed information must be indexed and classifed so that it can be digitally stored. The user can then find specific information by searching, sorting, browsing, or querying the database.

What is the origin and history of the Toxicology module?

The Toxicology module is the latest generation of the Haz-Map database that began with an idea in 1991, “Why can’t we have a relational database of toxic chemicals and occupational diseases to store and query information similar to ones used by companes to manage data about employees, products, and customers?”

How is the Toxicology module different from previous generations of Haz-Map?

1. The Agents table, containing chemical and biological agents, is the same except for additions to the content: links to the 2008 Emergency Response Guidebook; NTP and ACGIH cancer designations; images of the chemical structures; and Emergency Response Planning Guideline (ERPG) values.

2. Improvements to the user interface for Agents include hyperlinks to PubMed abstracts, hyperlinks to other chemicals in the database (e.g., “See ‘Formaldehyde.’”), calculated values of saturated concentrations at room temperature, and a calculator to convert between ppm and mg/m3.

3. The Diseases table covers the same occupational diseases; it also covers food poisoning (30 diseases), biological weapons (12 diseases), and chemical/radiological weapons (6 diseases).

4. The user-interface for Diseases has been improved to include ten syndromes and seven latency periods that can be used to “zoom in” to specific diseases.

What Is the content of the Toxicology module? Is it occupational toxicology only?

Diseases are mainly occupational diseases, but Agents display adverse effects based on occupational and non-occupational evidence. Adverse effects reflect high-dose cases in humans (ingestion of overdose) as well as studies of experimental animals (ingestion, inhalation, or other route). The Toxicology module does not include information about medical toxicology (drugs) and plant toxicology unless they are significant occupational hazards.

How many chemical and biological agents are there in the Toxicology module?

The first chemicals added to the database were the 700+ chemicals from the NIOSH Pocket Guide. After that were added the agents that cause occupational asthma from a list published by Malo and Chan-Yeung [Asthma in the Workplace, p. 825-866]. Many of the agents causing occupational asthma are biological agents, e.g., dusts and mists from molds, Western red cedar, flour, plants, insects, laboratory animals, and enzymes. There are currently 183 biological agents in the database, and 133 of these cause occupational asthma.

As of September 2008, there are a total of 2008 agents in the database. Several hundred agents are being added every year. There are also 3075 new chemicals that have not yet been published. These chemicals were found in several databases (HSDB, ACGIH, and Quick CPC), and the author’s assistant is working to develop the profiles for these chemicals within the next one to two years.

Who is the author of the Toxicology module?

The author is Jay A. Brown, MD, MPH, who is Board Certified in Occupational Medicine and a member of the American College of Occupational and Environmental Medicine (ACOEM) and the American Conference of Governmental Industrial Hygienists (ACGIH). Jay’s scientific paper entitled “An Internet database for the classification and dissemination of information about hazardous chemicals and occupational diseases” was published in the American Journal of Industrial Medicine 51:428-435 (2008).

How is information in the Toxicology module organized?

The two levels of information are:

1. Agents: This is the industrial hygiene perspective. Is the agent toxic?
2. Occupational Diseases: This is the epidemiology perspective. Is the agent a hazard?

What is the difference between “toxic” and “hazardous”?

“A distinction is made between toxicity and hazard. An extremely toxic chemical that is in a sealed container on a shelf has inherent toxicity but presents little or no hazard. When the chemical is removed from the shelf and used by a worker in a closed space and without appropriate protection, the hazard becomes great. Thus the manner of use affects how hazardous the substance will be in the workplace.” [Rosenberg J, Israel LM. Clinical Toxicology. In: LaDou, p. 175]

and

“The mere presence of a particular hazard in an environment does not indicate that human exposure has occurred, nor does it provide an adequate basis for determining potential risk. The exposure potential must be assessed for an individual or group to determine the actual risk. . . . Hazard evaluation involves both the toxicity of the chemical or material and the opportunity for exposure to cause disease.” [Van Ert MD, Crutchfield CD, Sullivan JB. Principles of Environmental and Occupational Hazard Assessment. In: Sullivan , p. 32]

and

“The hazard is a combination of the inherent toxicity of the substance and the likely exposure.” [PMID 16857649] To find the toxicity of a chemical, look at the Agent level. To find the hazard, look at the Disease level.

What is the cardinal rule of toxicology?

The main principle is that “the dose makes the poison” meaning that there is a threshold dose below which adverse effects do not occur. We all need a daily low dose of iron to be healthy, but ingestion of an overdose of iron tablets is one of the most common causes of poisoning. If the dose is too high, poisoning occurs. The human body is equipped with ingenious mechanisms for excreting poisons and repairing injured tissues, but there is a threshold dose above which permanent damage and possibly death will occur.

What is PMID?

PMID stands for PubMed identification number. If you go to PubMed at http://www.ncbi.nlm.nih.gov/sites/entrez and enter the PMID in the search box, you can find the full reference cited.

What are “Reference Tags”?

In addition to PMID, reference tags are used to document the sources of information in the database. LaDou and Sullivan are examples of reference tags. Full references are accessible on the Bibliography page.

Clinically separating “acute-severe”, “acute-moderate” and “subacute” seems difficult to me.  Although I know what the words mean I’m not sure the distinctions are clear when seeing a patient.

A health practitioner is seeing a patient in a clinic, emergency room, or hospital. How would you classify the disease?

1. Acute-severe. The onset is acute, severe, and life threatening. For chemicals, the length of exposure is less than 24 hours. The patient is likely to be admitted to the hospital.

2. Acute-moderate. The onset is acute, but not life threatening. For chemicals, the length of exposure is less than 24 hours. The patient is likely to seek medical attention, but not be admitted to the hospital.

3. Subacute. The onset of symptoms is gradual over a period of less than 2 months. The syndrome may be a cumulative exposure with short latency, e.g., lead poisoning.

4. Chronic. The onset of symptoms is gradual over a period longer than 2 months. A chronic syndrome induced by chemicals may represent 1) A cumulative exposure with a long latency, or 2) Adverse effects that persist two months or longer after a brief high exposure.