P

Phthalates

Physical Properties

Phthalates are a family of compounds made from alcohols and phthalic anhydride. They are oily, colorless, odorless liquids that do not evaporate readily.

Uses

Most phthalates are used to make vinyl (polyvinyl chloride [PVC]) soft and flexible. Added to PVC, phthalates allow the long polyvinyl chloride molecules to slide against one another. Phthalates are found in many consumer products including vinyl tile, clothing, artificial leather, tarps, automotive trim, weather stripping, latex adhesives, building products, sheathing for wire and cable, swimming pool linings, children’s toys, and medical devices such as IV bags and tubing. The chemical names of some of the common phthalates are: butyl benzyl phthalate (BBP), di-n-butyl phthalate (DNP), di-(2-ethylhexyl) phthalate (DEHP), di-isodecyl phthalate (DIDP), di-isononyl phthalate (DINP), di-n-hexyl phthalate (DnHP), and di-n-octyl phthalate (DnOP).

Sources of Exposure in Iowa

People with the greatest potential for exposure to phthalates work at industries using phthalates in the manufacture of plastics and consumer products. Exposure to phthalates in an industrial setting occurs through inhalation and dermal exposure. Since phthalates are used in many consumer products, the general population is exposed to very small amounts of phthalates from skin contact with products that contain phthalates. Children may be exposed to small amounts of phthalates from mouthing plastic toys that contain phthalates. The largest exposure to phthalates most likely occurs in individuals who undergo extensive medical procedures using plastic IV bags and tubing.

Health Effects from Large Acute Exposures

Relatively little information is available regarding human health effects of large acute exposures to phthalates, since they are uncommon. One individual who ingested about 10 grams of DEHP complained of mild abdominal pain and diarrhea.

Health Effects from Smaller, Chronic Exposures

No adverse health effects have been documented in humans, including children, from long-term exposure to the small amounts of phthalates in consumer products. Laboratory animal tests indicate that exposure to small amounts of phthalates causes adverse developmental and reproductive effects, and can increase the weight of the liver and kidney. The dose given to these animals far exceed those to which humans are typically exposed. But, due to some concern about potential exposure to phthalates, the U.S Congress has taken steps to require children’s toys and child care articles to contain no more that 0.1 % of six types of phthalates. Exposures that may cause concern about adverse health effects are the exposure of infants undergoing significant medical procedures such as blood transfusions, and the exposure of a fetus if its mother undergoes significant medical procedures. The estimated exposure of infants undergoing significant medical procedures is similar to the level at which laboratory animals show adverse health effects. However, no conclusive evidence demonstrates that infants experience adverse health effects at this level. The Iowa Department of Public Health believes the benefit of undergoing the medical procedure far outweighs the potential adverse health effects of exposure to phthalates.

Protection from Exposure

Proper protective equipment is recommended for any person exposed to phthalates in the occupational setting.

Polychlorinated Biphenyls (PCBs)

CASRN 1336-36-3

Physical Properties

Polychlorinated biphenyls (PCBs) are synthetic organic compounds. There are no known natural sources of PCBs. PCBs are a class of chemical compounds in which 2-10 chlorine atoms are attached to the biphenyl molecule. PCBs enter the environment as mixtures of a variety of chlorinated biphenyl compounds known as congeners. PCBs are either oily liquids or solids, and are colorless to light yellow. They have no known smell or taste. PCBs do not readily break down in the environment and, therefore, may remain for very long periods of time. PCBs can bio-accumulate within organisms in the natural environment. Uses PCBs were discovered over 100 years ago, but their production and commercial use began in 1929. Because of their remarkable insulating capacity and flame-retardant nature, PCBs gained widespread use as coolants and lubricants in transformers and other electrical equipment. PCBs were also used in hydraulic fluids, synthetic resins, adhesives, inks, sealants, and caulking compounds. Manufacture and use of PCBs was banned in the United States in 1979.

Sources of Exposure in Iowa

PCBs have been released to the environment solely through human activity. They may result from incineration of PCB-containing wastes, leakage from older electrical equipment, and improper disposal or spills. PCBs are globally circulated, and present in all environmental media. The general population is exposed to PCBs primarily by eating contaminated foods, particularly fish, meat, and poultry; and inhalation. Both marine and freshwater fish may contain PCBs. PCBs accumulate in the fatty tissue of some fish more than others depending on what they eat, how long they live, and their position in the food chain. A person’s exposure to PCBs from fish will depend upon the PCB content of the tissue of the fish and the amount of fish the person eats. Since PCBs are no longer manufactured and used in United States, environmental concentrations are generally decreasing.

Health Effects from Large Acute Exposures

Exposure to large amounts of PCBs is rare. Only people who repair and maintain PCB transformers are likely to be exposed. Exposure to large amounts of PCBs may cause rashes or acne. Some studies of workers exposed to PCBs suggest they may also cause irritation of the nose and lungs, gastrointestinal discomfort, changes in the blood and liver, and depression and fatigue. This is not likely in the general population.

Health Effects from Smaller, Chronic Exposures

Longer-term exposure to low levels of PCBs may result from eating certain fish regularly. For most people, eating fish regularly will not result in exposure to very high levels of PCBs. Most of the concern about PCBs in fish is related to low birth weight, decrease in motor skills, and decreased short-term memory, and adverse effects on the immune systems of children whose mothers eat large amounts of fish before and during pregnancy. Research seems to indicate that the health benefits of including fish in the diet will most likely outweigh the risks of PCB exposure. PCBs are considered a human carcinogen.

Protection from Exposure

Since most exposure to PCBs results from eating fish, the Iowa Departments of Public Health and Natural Resources have developed a program to advise Iowa residents about species of fish showing higher levels of PCBs and other environmental contaminants. Information on the fish contaminant advisory program is included in the list of internet links below.

Polycyclic Aromatic Hydrocarbons (PAHs)

CASRN 130492-29-2

Physical Properties

Polycyclic aromatic hydrocarbons (PAHs) are chemicals formed during the incomplete burning of coal, oil, gas, wood, garbage, or other organic substances, such as tobacco and charbroiled meat. There are more than 100 different PAHs. Some of the more common PAHs are: acenaphthene, acenaphthylene, anthracene, benz[a]anthracene, benzo[a]pyrene, benzo[e]pyrene, benzo[b]fluoranthene, benzo[g,h,i]perylene, benzo[j]fluoranthene, benzo[k]fluoranthene, chrysene, dibenz[a,h]anthracene, fluoranthene, fluorene, indeno[1,2,3-c,d]pyrene, phenanthrene, and pyrene. PAHs generally occur as complex mixtures (for example, as part of combustion products such as soot), not as single compounds. PAHs usually occur naturally, but they can be manufactured. PAHs are made up of carbon and hydrogen atoms, grouped into at least two condensed aromatic ring structures. As pure chemicals, PAHs Are generally colorless, white, or pale yellow-green solids.

Uses

There is no known use for most of the PAHs, except as research chemicals. Anthracene is used as an intermediate in dye production and the manufacture of synthetic fibers, and as a diluting agent for wood preservatives. It is also used in smokescreens, as scintillation counter crystals, and in organic semiconductor research. Anthracene is used to synthesize the chemotherapeutic agent Amsacrine. Acenaphthene is used as a dye intermediate, in the manufacture of pharmaceuticals and plastics, and as an insecticide and fungicide. Fluorene is used as a chemical intermediate in many chemical processes, in the formation of polyradicals for resins, and in the manufacture of dyestuffs. Phenanthrene is used in the manufacture of dyestuffs and explosives and in biological research. Fluoranthene is used as a lining material to protect the interior of steel and ductile-iron drinking water pipes and storage tanks.

Sources of Exposure in Iowa

PAHs are present throughout the environment, and people may be exposed at home, outside, or at the workplace. Typically, a person will be exposed to a mixture, not to an individual PAH. People are most likely to be exposed to PAH vapors or PAHs attached to dust and other particles in the air. Sources include cigarette smoke, vehicle exhausts, asphalt roads, coal, coal tar, wildfires, agricultural burning, and residential wood burning. People may be exposed to PAHs in soil near areas where coal, wood, gasoline, or other products have been burned. PAHs may be in the soil at or near hazardous waste sites, such as former manufactured-gas plants and wood-preserving facilities.

Health Effects from Large Acute Exposures

Little published information about exposure to large amounts of PAHs is available. In general, the acute toxicity of PAHs increases as the molecular weight of a specific PAH increases. Health effects of large acute exposures to PAHs are often due to co-exposure to irritant gases.

Health Effects from Smaller, Chronic Exposures

Longer-term exposure to lower levels of PAHs mostly effects the lungs, gastrointestinal tract, kidneys, and skin. Workers exposed to PAHs have exhibited symptoms including cough, shortness of breath, throat irritation, chest pain, and vomiting of blood. There is some evidence that exposure to PAHs, particularly from smoking, accelerates atherosclerosis (narrowing and hardening of the arteries). Some PAHs are thought to be human carcinogens. Coal tar and coal tar pitches, which contain PAHs, are known human carcinogens.

Protection from Exposure

Everyone is exposed to low levels of PAHs. Limiting exposure to smoke and burning organic matter can reduce exposure to PAHs.