CHEMICAL CARCINOGENS CHEMICAL CARCINOGENS

What is a Chemical Carcinogen?  Any chemical compound which has been shown to cause cancer in humans or in animal studies.  Hundreds of individual compounds have been shown to induce cancers. Many thousands of additional compounds are “suspect” carcinogens.  Many are commonly used in laboratory procedures, manufacturing, and in industry.  Most cause localized base changes in DNA (exceptions are asbestos and diethylstilbestrol)

Categories of Known Human Carcinogens  Chemicals (organic and inorganic)  Agents encountered in occupational exposure (e.g., benzene)  Drug Therapies (particularly chemotherapy)  Environmental agents (UV light, asbestos, and tobacco)

Chemical Carcinogens

Chemical Carcinogens Continued

How is Chemical Carcinogenicity Determined?  Epidemiological studies determine the relationship between a cancer suspect chemical and a human population over a long period of time.  Animal studies directly induce cancer in test animals using a large sample of animals, usually of two or more species with varying dose and time parameters.  Experiments with animals are based on the premise that chemicals that produce cancer in animals will have similar effects on human cells. Most known human carcinogens produce cancer in experimental animals.

Ames Test for Carcinogenicity

How do Carcinogens Enter the Body?  Skin absorption.  Ingestion. Swallowing of a carcinogen.  Inhalation. Breathing gases, fumes, and vapors is the most common form of exposure.

What Organs do Carcinogens Most Frequently Attack?  Lungs  Liver  Kidney  Reproductive system  Skin  Many other organs and tissues

What Factors Influence the Development of Cancer?  Dose - amount and duration of exposure. The lower the dose the least likely you are to develop cancer or related diseases.  Environmental or lifestyle factors:  Cigarette smoking (co-carcinogen)  Alcohol consumption (co-carcinogen)  Diet - high fat consumption, low fiber  Fitness level  Age, race, and gender  Geographic location - industrial areas, UV light  Inherited conditions (Xeroderma pigmentosum) and genetic makeup

How Can One Reduce Their Exposure to Carcinogens?

Minimizing One’s Exposure to Carcinogens  General room ventilation - 10 or more changes of air per hour. Designed to reduce exposures below the permissible exposure limit.  Fume hoods.  Local ventilation - exhaust (sometimes supply) at the point of use of a chemical.  Biosafety cabinet--used for anticancer drugs, viruses.  No bench top work in a laboratory setting.

Personal Protective Equipment  Respiratory protection - dust masks, respirators. Respirators are primarily for use in non-lab areas, except for emergency response (spill cleanup)-- shops, floor stripping, construction operations (painting).  Eye protection - safety glasses, splash goggles, and face shields.  Hand protection - gloves and protective sleeves.  Protective clothing - lab coats.

Personal Hygiene  No smoking, eating, drinking or application of cosmetics is permitted in areas where carcinogens are in use (or in any lab area!). No mouth pipetting!  Wash hands and any exposed skin if potentially contaminated - face, neck, forearms, etc.  No shorts or open-toed shoes.  Remove lab coat or other potentially contaminated protective clothing before leaving the work area. Lab coats need to be cleaned regularly.  Contaminated disposable clothing should be treated as hazardous waste.

Labeling of Containers  All containers of chemical carcinogens need to have a warning label affixed to them.  “DANGER : Contains ___________ CANCER HAZARD”

Storage of Carcinogens  Carcinogens must be stored separately from other materials.  Separated by shelving system or secondary containment.  Storage areas must be labeled “Danger-- Carcinogens Stored Here.”

Disposal of Carcinogen Waste Materials  All contaminated substances (paper towels, supplies, etc.) must be properly labeled and sent out for incineration as Regulated Medical Waste  Carcinogens may never be disposed of in the ordinary trash.  Dry wastes must be autoclaved and shipped out as regulated medical waste (“Chemotherapeutic Agents”).

Ultimate Goals Determine the various mechanisms by which known carcinogens act and to identify the function of specific genes that confer increased susceptibility, or which are the targets of environmental carcinogens.