Why the chemical is of concern:

Naphthalene is an organic compound found in coal, petroleum and related products such as creosote and asphalt. Naphthalene exposure has been shown to lead to hemolytic anemia in humans, a condition in which red blood cells break down and die prematurely (see here, here and here). High levels of exposure can also cause nausea, vomiting, headaches, dizziness, diarrhea, blood in the urine and yellowing of the skin (jaundice). Ingestion of naphthalene likely causes liver and kidney damage. Other hazards include eye irritation and cataracts.

Animal studies have shown an increased incidence of lung and nasal tumors, as well as eye injuries resulting in cataracts. A few case studies suggest that the latter effect may also occur in humans, but this has not been substantiated in formal epidemiological studies. Naphthalene is carcinogenic in animal studies, and has been classified as possibly carcinogenic to humans by the International Agency for Research on Cancer (IARC) and as reasonably anticipated to be a human carcinogen by the Environmental Protection Agency (EPA).

Workers employed in the coal-tar, wood preservation, tanning, ink and fabric dying industries may be exposed to high levels of naphthalene in the workplace.

In the human body, naphthalene is metabolized to form several compounds, including 1- and 2- naphthol and naphthoquinones which are themselves toxic. These metabolites can cause methemoglobinemia (an abnormal build-up of hemoglobin). Reaction of naphthalene metabolites with sulfate or glucuronic acid – termed conjugation – aids in their excretion. Newborns are unable to conjugate naphthalene, however, and are thus more susceptible to napthalene toxicity.

Children have exhibited hemolytic anemia after ingesting mothballs or using fabrics treated with naphthalene insecticides. Pregnant women, through their own exposure, may also pass naphthalene to their unborn children. Naphthalene can move from the mother’s blood into the unborn baby’s, and can also be transferred through breastfeeding. In one case study, a woman inhaled fumes from mothballs while pregnant. She and her newborn child exhibited symptoms of hemolytic anemia and methemoglobinemia, and in treating the infant a double-volume blood transfusion was required.

In a case study of 21 newborns in Greece, naphthalene exposure was linked to hemolytic anemia, jaundice and kernicterus, a severe, potentially fatal jaundice-related syndrome producing neurological effects (also see here). Twelve of the newborns in the study were deficient for the enzyme glucose-6-phosphate dehydrogenase (G-6-PD), while the remaining nine infants had normal enzyme levels. This enzyme deficiency is genetically inherited and affects the body’s ability to break down and excrete naphthalene and its metabolites.

Individuals with the G-6-PD deficiency are at a greater risk of developing hemolytic anemia. The frequency of the G-6-PD deficiency varies across different populations, placing some at higher risk for naphthalene-induced illness. This enzyme deficiency is more common in African-Americans and people of Middle Eastern or Mediterranean descent. In a cohort study of 500 African American newborns, G-6-PD deficiency was found in 12.8% of the infants. The G-6-PD deficient infants in this study had a higher occurrence of hemolysis and jaundice, and required higher levels of treatment, than infants without the enzyme deficiency.

Naphthalene is released into the environment from industrial and domestic sources. The chemical partially dissolves in water, and binds weakly to soil. It may evaporate from the surface of bodies of water, or be broken down by aquatic bacteria. In the atmosphere, naphthalene breaks down from moisture and sunlight, usually within one day.

Where the chemical is found:

As noted earlier, naphthalene is found naturally in fossil fuels like coal and petroleum (crude oil). The burning of fossil fuels and wood releases naphthalene into the air, and as a result, naphthalene is a common pollutant found in urban air. It is also the single most abundant compound found in coal tar.

Naphthalene is used in the synthesis of several chemicals, including phthalate plasticizers, dyes, resins, and synthetic leather tanning agents. It is commonly used in industry as a starting material in the manufacture of synthetic plastics, including polyvinyl chloride (PVC) plastics. Naphthalene is used in toilet deodorant blocks, household and automobile products, and as a repellant in moth balls and moth flakes. Naphthalene is present in cigarette smoke and motor vehicle exhaust.

Current Regulation:

Occupational exposure to naphthalene is regulated by the Occupational Safety and Health Administration (OSHA). In the workplace, naphthalene levels may not exceed 10 parts per million (ppm) over an 8 hour work day, during a 40 hour work week. The National Institute for Occupational Safety and Health (NIOSH) has stated that naphthalene exposure exceeding 500 ppm is immediately dangerous to life and health.

The Environmental Protection Agency (EPA) considers naphthalene to be reasonably anticipated to be a human carcinogen and has recommended safe levels of naphthalene in drinking water. EPA has determined that it is unsafe for children to drink water containing greater than 0.5 ppm of naphthalene for more than 10 days, or greater than 0.4 ppm of naphthalene for longer than seven years. For adults, EPA advises not drinking water contaminated with greater than 1 ppm naphthalene for more than 7 years or drinking water with more than 0.1 ppm naphthalene over a lifetime.

What should be done:

To limit your exposure to naphthalene, avoid generating and inhaling smoke from fireplaces, heating, and cooking appliances that use petroleum-based fuels or wood. Avoid tobacco smoke, and check toilet deodorizers to see if they use naphthalene before bringing them into your home. Extreme precaution should be taken when handling naphthalene-containing moth repellants as well as blankets and clothing stored with them. Some moth-repellant alternatives are suggested here.

Individuals with G-6-PD deficiency should be especially wary of products containing naphthalene and avoid exposure entirely. Workers in naphthalene-related industries should wear appropriate personal protective equipment and work in well ventilated areas.

The hazards presented by consumer products containing naphthalene raise a much bigger issue: the inadequate regulation of toxic chemicals in the U.S. Consumers are often not appropriately informed of the presence of toxic chemicals in the products they use or are otherwise exposed to, and the possible harms such chemicals pose to their health. Current legislation, most notably the Toxic Substances Control Act (TSCA), fails to adequately regulate substances like naphthalene. Some 60,000 existing chemicals, including naphthalene, were grandfathered into TSCA at the time of its enactment in 1976 without requiring any health or safety data or assessment. Unfortunately, this lack of data and safety assessment hasn’t improved much in the past 35 years. This outdated legislation is in need of serious reform to give EPA the authority is needs to require basic information on chemicals from the chemical industry. Effective reform, like that presented by Senator Lautenberg in the Safe Chemicals Act of 2011, would help ensure the safety of chemicals before they reach or as a condition for staying on the market, offering better protection for consumers. Help make this possible by showing your support here.

Why the chemical is considered of concern:

Styrene is a colorless liquid, which is reacted with itself or other chemicals to produce polystyrene and synthetic plastic resins. The U.S. National Toxicology Program has classified styrene as a chemical reasonably anticipated to be carcinogenic to humans. Exposure to high levels of styrene in occupational settings has been associated with an increased risk for lymphohematopoietic cancers, which include leukemia and lymphoma. These cancers are characterized by abnormally high levels of white blood cells, which are thought to result from DNA mutations. In the human body, styrene is metabolized to styrene-7, 8-oxide, which has been shown to cause DNA damage in white blood cells. This damage is thought to result in chromosomal abnormalities in lymphocytes, a potential mechanism for styrene-induced cancer. Styrene exposure may also increase the risk for other cancers, including those of the esophagus and pancreas.

Styrene is hazardous if inhaled or ingested, and by means of skin or eye contact. Chronic exposure to styrene, or acute inhalation at high levels, negatively affects the nervous system. Changes in color vision, slowed reaction time, lethargy, headaches, memory deficits, hearing loss, and concentration and balance problems can occur and may be permanent. Styrene is also suspected to be toxic to the kidney, liver and respiratory system [pdf]. In animal studies, mice exposed to styrene developed lung tumors and nasal passage linings were damaged.

Styrene may be inhaled from off-gassing of building materials, tobacco smoke, photocopier fumes [pdf], and automobile exhaust. It is incorporated into a widely used polymerized plastic, polystyrene. While the polymer is non-toxic, styrene may leach from polystyrene containers into food at low levels. Styrene exposure has also occurred from drinking and bathing in contaminated water.

Occupational exposure occurs through inhalation and skin contact. Workers in the reinforced plastic, styrene-butadiene rubber, and styrene monomer and polymer industries are especially at risk for exposure. Workers in car, truck and boat fabrication industries are also likely to be exposed to high levels of styrene.

A cohort study of 17,924 workers in the styrene-butadiene rubber industry in North America found that leukemia-related mortality was elevated 16% compared to the general population. Cases of mortality were even higher among those having worked 20 or more years in the industry. Leukemia incidence was concentrated in those with jobs with a higher likelihood for chemical exposure.  However, uncertainty remains about the specific chemical agent(s) that contribute to the increased leukemia incidence.  In addition to styrene, workers could have also been exposed to the chemicals butadiene and dimethyldithiocarbamate.

Styrene is detected in air, water and soil as a consequence of its release from manufacturing processes involving styrene, as well as from the use and disposal of styrene-containing products. Styrene breaks down [pdf] in the air within one to two days and binds with ozone and hydroxyl radicals in the atmosphere. In bodies of water, styrene volatilizes quickly, and in soil, styrene is typically broken down by bacteria and microorganisms.

Where the chemical is found:

Styrene is used to manufacture polystyrene, a widely used category of plastic. Polystyrene is used in CD hard cases, plastic silverware and other rigid molded plastics. Polystyrene foams, like Styrofoam™, are commonly used for their insulating properties and are found in building and home maintenance materials, craft supplies, packaging peanuts and disposable coffee cups.

Styrene is also used to produce reinforced plastics and rubbers used in insulation (building construction and refrigeration equipment), pipes, automotive parts, tires, printing cartridges, food packaging and carpet backing. Trace amounts of styrene may also be found naturally in some foods.

Current regulation:

Styrene is regulated by the Occupational Safety and Health Administration; worker exposure is limited to an average of 100 parts per million (ppm) over an 8-hour workday during a 40-hour work week. The US Food and Drug Administration regulates styrene in bottled drinking water; the concentration of the chemical may not exceed 0.1 milligrams per liter (mg/L).

Styrene is regulated as a contaminant under the Safe Drinking Water Act. The Environmental Protection Agency (EPA) has determined that exposure to styrene from drinking water is not expected to cause adverse health effects in children at concentrations at or below 20 mg/L for one day, or 2 mg/L for 10 days. EPA has also indicated that lifetime exposure to 0.1 mg/L styrene in drinking water is not expected to cause adverse effects. Styrene is listed under the EPA’s Emergency Planning and Community Right to Know Act (EPCRA), and as part of the Toxic Release Inventory, industries must report environmental releases and waste management of styrene.

What should be done:

You can play a role in limiting your exposure to styrene. Try to avoid inhaling cigarette smoke and car exhaust. Don’t microwave food or beverages or put hot drinks in polystyrene foam containers and cups. Heat may permit styrene monomers to leach from the polystyrene material and into your food or drink.

Workers who use styrene-containing materials can protect themselves from skin absorption of the substance by wearing protective gloves and clothing. Exposure by inhalation can be reduced with appropriate ventilation of the workspace.

But despite all personal measures, the significant potential for adverse health effects from exposure to styrene really demonstrates a larger problem: inadequate chemicals policy in the U.S. The current legislation, the Toxic Substances Control Act (TSCA), is flawed and limits the EPA’s authority to require chemical information from industry or ensure safe use. Through effective reform, like that presented in the Safe Chemicals Act, measures will be put in place to ensure the safety of all chemicals on the market and better inform and protect consumers from the harms of toxic chemicals. Show your support for smart, safe chemicals policies here.

Why the chemicals are considered of concern:

Diisocyanates are a group of chemicals—within the larger isocyanate family of chemicals—primarily used to make polyurethane polymers found in products ranging from bowling balls to insulation foam. During polyurethane synthesis, diisocyanates react with other chemicals—a process called curing—to form polyurethane polymer chains. When the curing reaction is complete and virtually no unreacted diisocyanates remain, the polyurethane product is said to be “cured.” Cured products, which contain fully reacted diisocyanates incorporated into polyurethane polymers, are essentially non-toxic. However, unreacted diisocyanates – whether those remaining unreacted in cured products or those present in uncured products – are highly toxic, especially to the respiratory system.

Diisocyanates are known to induce and exacerbate asthma, damage the lung, cause irritation of the skin, eyes, nose and throat, and in severe cases, result in death. They have also been linked to cases of hypersensitivity pneumonitis (inflammation of the lungs) and pulmonary edema (fluid in the lungs). A specific diisocyanate – toluene diisocyanate (TDI) – has been identified by the International Agency for Research on Cancer (IARC), as carcinogenic in animals, while the U.S. National Toxicology Program (NTP) considers it a "reasonably anticipated human carcinogen."

Exposure to diisocyanates occurs most often through inhalation, although skin contact can also cause irritation and sensitization. Exposure potential is increased when products containing diisocyanates are sprayed or heated.

Diisocyanates are chemical sensitizers, that is, repeated exposure results in increasing sensitivity to their effects such that even low levels of exposure can trigger severe asthmatic reactions. In addition, asthmatic response can be delayed by up to 12 hours following exposure.

The two most commonly used diisocyanates are Methylene Diphenyl Diisocyanate (MDI) and Toluene Diisocyanate (TDI), which make up about 90% of the entire diisocyanates market. They are frequently used in the automobile and construction industries and are a leading cause of occupational asthma (see here,  here and here). The National Institute for Occupational Safety and Health (NIOSH) highlights several case reports of isocyanate-induced asthma, respiratory problems, and in a few cases, death. In fact, each year about 280,000 workers are exposed to diisocyanates, yielding a substantial prevalence of isocyanate-induced asthma.

Consumers are vulnerable bystanders to commercial application of diisocyanates when used to seal concrete, wooden decks and roofs. More recently, potential exposure of the general public to diisocyanates has risen due to the increasing availability of household products containing these chemicals. In particular, do-it-yourself homeowners may inadvertently expose themselves to higher levels of diisocyanates as commercial-grade polyurethane products become ever more available to consumers.

Children are especially susceptible to diisocyanate exposure and resulting illness. Diisocyanate vapors are heavier than air and settle close to the ground, leaving children more vulnerable to inhalation and skin absorption. In addition, children breathe in more air relative to their body size compared to adults. In one case study, school children were exposed to MDI from a polyurethane-based artificial surface applied to an athletic track. Of the children exposed to fumes from the track material, 60% with no prior history of asthma reported asthma-like symptoms of shortness of breath and coughing, and many students suffered eye and throat irritation, nausea, headaches and vomiting.

Air releases of diisocyanates are of concern because of the potential for direct inhalation exposure. Diisocyanates can also react with water in the air – a process called hydrolysis – to form other hazardous chemical compounds called diamines (TDI forms toluene diamine; MDI forms methylene diphenyl diamine). The stability of diisocyanate and diamine compounds in air depends in part on humidity levels. Under conditions of low humidity, diisocyanates may remain stable enough to be transported across long distances.

Where the chemicals are most commonly found:

Diisocyanates are found in a broad range of products, including adhesives, sealants, binders, coatings, spray paints, whiteboard paints, rubbers, plastics and crafts materials. They are used extensively in industries that produce and repair automobiles, boats, furniture, appliances and electronics.

Many other products contain diisocyanates in an uncured and much more toxic form, however, usually in the form of liquids, sprays, aerosols or foams that stiffen as polyurethane polymers are formed through the curing process. The curing time for polyurethane products has been shown to be variable. As a result, the recommended amount of time one should wait before entering an area in which diisocyanate-containing products have been applied also varies. The curing rate depends on several factors, including product type, application method and ventilation. Diisocyanate-containing products remain hazardous until curing is complete.

Of note, government programs have incentivized the use of polyurethane foams for increasing energy efficiency. These products are used for insulation and are available in uncured forms as “pour in place” foam, spray polyurethane foam (SPF), and one-component foam (OCF).

Current regulation:

The Occupational Safety and Health Administration (OSHA) regulates worker exposure to diisocyanates through the establishment of permissible exposure limits (PEL). OSHA also requires the use of personal protective equipment when workers are using diisocyanates. Employers are charged with determining appropriate protective equipment for hazards encountered by their employees and training of employees on how and when to use such equipment.

Under the Clean Air Act, diisocyanates are regulated as hazardous air pollutants. The Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) regulate diisocyanates as hazardous when present in wastes.

Twenty diisocyanates are subject to Section 313 of the EPA’s Emergency Planning and Community Right to Know Act (EPCRA). This section requires businesses to report environmental chemical releases and waste management of identified toxic chemicals. The reported information is subsequently made publicly available on the EPA Toxics Release Inventory.

In the European Union, measures have been taken to limit MDI in consumer products under the EU’s REACH Regulation. Since December 27, 2010, MDI has been banned in quantities greater than 0.1% in products sold to the general public. Products exceeding that limit may only be sold to consumers if they contain approved protective gloves and are visibly marked with the chemical hazards, application instructions and warnings of the health risks associated with product use.

What should be done:

Users of products containing uncured diisocyanates should take all necessary precautions to protect themselves when using these products. This starts with informing yourself as to whether the products you use contain diisocyanates. Call the product manufacturer when chemical ingredients aren’t listed or if you are unsure whether listed ingredients are diisocyanates. Do-it-yourselfers should be especially wary and take extreme precaution when using uncured polyurethane products, including using personal protective equipment (PPE). Workers must also use appropriate PPE and those sensitized to diisocyanates should cease work with these chemicals to avoid severe health complications.

Industry should look towards the use of new non-isocyanate polyurethane alternatives. There is a new class of non-isocyanate polyurethanes and isocyanate-free expanding foam products that show potential. These products are purported to be equally as effective as their isocyanate counterparts, less costly to produce and safer, all claims that must be further evaluated and substantiated.

The widespread, expanding and largely unregulated use of dangerous diisocyanates in consumer products underscores the larger problem of inadequate chemicals policies and the need for reform of the Toxic Substances Control Act (TSCA). Effective TSCA reform would assure that full safety data would be generated and made available to consumers, and that consumer uses of these chemicals be shown to be safe. As it stands, there is little information on consumer uses and consumer exposure to diisocyanate-containing products. Unfortunately, current TSCA does not provide EPA with authority to require better chemical use information from industry, let alone adequate chemical testing, as a condition for entering or remaining on the market.

In April 2011, Senator Lautenberg introduced legislation that would provide critical reforms to TSCA: the Safe Chemicals Act of 2011. Among other things, this legislation would enable EPA to obtain and provide public access to better use, hazard and exposure information on chemicals. This necessary reform would improve public protection from diisocyanates and the thousands of other chemicals poorly regulated in the US. Show your support for stronger toxic chemicals regulation here.

Why the chemicals are considered of concern:

Polybrominated diphenyl ethers (PBDEs) are synthetic chemicals added to foam cushioning, plastics, and other materials used in a variety of consumer products to make them less likely to catch fire and burn. PBDEs are suspected endocrine disrupting chemicals, with neurobehavioral effects, identified by the EPA as the critical health impact of concern for humans.

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