Imported miniblinds: a potential source of lead exposure for young children.

Introduction

Lead poisoning is the number one environmental health threat to children. Although childhood lead poisoning is completely preventable, it still occurs in the United States at a rate far greater than is acceptable for preventable infectious diseases (1). In Arizona, the Arizona Department of Health Services (ADHS) Office of Environmental Health (OEH) conducts statewide lead-poisoning prevention activities and maintains a lead-poisoning registry of elevated blood lead levels in both children and adults. Physicians and laboratories are required to report all blood lead levels of 10 micrograms per deciliter ([[micro]gram]/dL) or more (2). All families that have children with blood lead levels of 10 to 19 [[micro]gram]/dL receive educational information on the prevention of lead poisoning. If blood lead levels are 20 [[micro]gram]/dL or greater, OEH staff conduct on-site environmental investigations, including family counseling and appropriate environmental sampling.

In February 1995, ADHS linked a case of childhood lead poisoning to a previously unsuspected source of lead: dust from imported plastic miniblinds. While lead-based paint remains the most common and serious source of lead exposure, plastic miniblinds may be an unrecognized source in many cases of childhood lead poisonings (1). Young children can be exposed to the lead dust by touching the miniblinds and subsequently putting their hands in their mouths or by mouthing on the blinds directly. Over 25 million of these miniblinds are imported to the U.S. annually (3).

This paper describes the initial case identified by ADHS and the actions that led to the June 1996 U.S. Consumer Product Safety Commission warning that parents of children under six years of age should remove plastic miniblinds from their homes (4).

Case Description

In May 1994, a 10-month-old Hispanic male in San Luis, Arizona, was reported to OEH by his physician with an elevated blood lead level of 20.2 [[micro]gram]/dL. Over the next eight months, blood lead levels fluctuated from 19.7 to 46.0 [[micro]gram]/dL (Table 1). OEH staff conducted two investigations of the child's residence during this period.

Environmental Investigation

The child's residence was a mobile home estimated to he 20 to 30 years old. There were no painted surfaces inside the home, only wood paneling and formica, which tested negative for lead with field lead test kits. A varnished kitchen cabinet in good condition reacted slightly to field lead test kits. Lead was not detected in a dust wipe taken from the kitchen floor, indicating that the home was not grossly contaminated with lead. No lead was detected in the exterior painted aluminum siding, and lead concentrations in water and soil samples were below limits set by federal standards and guidelines. Low levels of lead-based paint were found outside the home on a child's desk, a utility post, and an evaporative cooler (Table 2). These low-level sources were not considered to be a significant source of lead exposure for the child. The family was advised on how to reduce or remove possible sources of lead exposure.

Information obtained from the mother did not identify any other potential lead exposures, such as the use of folk medicine powders, imported pottery, or occupational take-home exposures. OEH staff conducted environmental investigations at the homes of two other family members, whom the child frequently visited, but no sources of lead exposure were found. After the child underwent chelation therapy and his blood lead level remained elevated at 37 [[micro]gram]/dL, a third investigation was conducted in January, 1995.

TABLE 1

Blood Lead Levels of Child Exposed to Plastic Miniblinds

Date                     Blood Lead Level ([[micro]gram]/dL)

May 1994                               20.2
May 1994                               21.3
August 1994                            19.7
November 1994(a)                       46.0
January 1995                           37.0
January 1995(b,c)                      36.0
April 1995                             27.0
October 1995                           16.0
August 1996                            13.0
December 1996                          17.0
February 1997                          11.0

a First round of chelation.

b Miniblinds removed from home.

c Second round of chelation.

The third visit to the child's residence identified imported horizontal plastic miniblinds as a possible lead source. Two sets of off-white miniblinds hung lower than the window openings next to the child's bed and within reach of the child. The mother reported that he frequently touched and mouthed on the [TABULAR DATA FOR TABLE 2 OMITTED] miniblinds when he stood on his bed to look out the window. This information was uncovered when investigators visited each room of the mobile home with the mother and asking specifically what the child mouthed on in each room. Field test kits used on the l-inch horizontal plastic slats of the miniblinds produced a positive reaction, indicating the presence of lead. OEH staff then took a dust wipe sample from the miniblinds to determine if lead found on the surface of the plastic slats could be easily removed and ingested via the child's hand-to-mouth behavior. The dust wipe revealed 1,021 micrograms per square foot ([[micro]gram]/[ft.sup.2]) of lead dust, twice the federal Housing and Urban Development (HUD) guidelines of 500 [[micro]gram]/[ft.sup.2] for windowsills (5). Digestion analysis of the plastic slat material revealed 2,100 milligrams per kilogram (mg/kg) of lead. These results were, however, below the state standard of 5,000 mg/kg for lead-based paint (2).

ADHS staff advised the mother to remove the miniblinds to prevent any further exposure to lead-contaminated dust. The physician prescribed chelation, and the child's blood lead level dropped to 16.0 [[micro]gram]/dL in October 1995.

Laboratory Testing of Plastic Miniblinds

ADHS conducted additional tests in November 1995 to confirm the presence of lead in other imported plastic miniblinds. Eleven samples of imported plastic miniblinds were collected from a variety of homes and businesses (Table 3). The miniblinds had 1-inch-wide curved horizontal slats ranging in color from off-white to blue. All of the samples were reported to have been purchased at national department and discount stores. The ages of the miniblinds ranged from new (purchased by OEH staff) to more than five years old. Eight of the sampled miniblinds were labeled as imported from China, Taiwan, or Mexico. Labels indicating country of origin were missing from two of the sets.

Laboratory testing included dust wipes and, when possible, digestion analysis of the horizontal slats to identify the lead content (Table 3). Nine dust wipe samples were submitted to a private laboratory for analysis by NIOSH Method 7082; one dust wipe was taken from each of the eight sets of miniblinds, then one set of miniblinds was washed with a phosphate soap and another dust wipe was taken so that the effects of cleaning the blinds could be observed. The laboratory results ranged from 255 to 2,874 [[micro]gram][ft.sup.2] of lead dust. Five of the samples exceeded the HUD guidelines for windowsills of 500 [[micro]gram]/[ft.sup.2] (5). The three highest results were from miniblinds manufactured in China. Dust wipes confirmed that the lead dust could be removed easily from the surfaces of the blinds and could be ingested via hand-to-mouth behavior.

For six sets of the miniblinds, ADHS staff analyzed lead content by cutting pieces of the plastic slats for digestion analysis. Staff were unable to obtain permission from homeowners to cut samples from the other two sets of miniblinds. Lead was identified in all six cut samples, with concentrations ranging from 1,830 mg/kg to 6,730 mg/kg. While the concentration of lead in two of these samples exceeded the state lead-based paint standard of 5,000 mg/kg, there are no federal or state standards or guidelines for lead content in plastic (2). ADHS concluded from the initial case and the additional sampling that the miniblinds posed an unforeseen health hazard to young children because of frequent hand-to-mouth behavior. These findings indicated a significant public health hazard because of the millions of miniblinds found in homes across the nation.

Public Health Actions

The findings in the initial case were presented to the U.S. Consumer Product Safety Commission (CPSC) along with the miniblind test results. In December 1995, ADHS issued a press release alerting parents of young children about potential exposure to lead dust from these miniblinds (6). This release attracted attention nationwide from federal, state, and local health agencies. At the time of the press release, CPSC did not concur with the ADHS position that the miniblinds posed a hazard to young children. Through the National Window Coverings Safety Council, [TABULAR DATA FOR TABLE 3 OMITTED] which represents the majority of manufacturers, CPSC did request that the miniblinds be reformulated without lead additives in the plastic (4). The North Carolina Health Department attributed several cases of childhood lead poisoning to imported plastic miniblinds in March 1996 (7).

Efforts by ADHS to convince CPSC that imported plastic miniblinds contained hazardous amounts of lead were successful in June 1996, when CPSC issued a nationwide warning to parents of young children about the potential health hazard posed by imported miniblinds. This warning was issued after tests with scanning electron microscopy technology, conducted at NASA's Goddard Space Flight Center and the U.S. Army's Aberdeen Test Center, confirmed that the polyvinyl chloride (PVC) used in miniblinds deteriorated after exposure to sunlight and heat. Electron microscopes were used to confirm that the lead dust present on the miniblinds originated directly from the miniblinds themselves and not from a secondary source, such as deteriorating lead-based paint. A risk analysis conducted by CPSC based on this testing projected that a child who ingested the dust from 1 square inch or less of one horizontal slat every day for 15 to 30 days would present blood lead levels above the Centers for Disease Control and Prevention (CDC) guideline of 10 [[micro]gram]/dL (1,4).

Lead as an Additive in PVC

Miniblinds made from PVC were a previously unsuspected source of lead exposure for children. Lead has, however, long been used as an additive in plastic. The use of lead as a stabilizer in the manufacture of PVC was first documented in a 1924 British patent. Without the addition of stabilizing agents such as lead, PVC becomes brittle and hard, cracking easily when exposed to heat and light (8). Heat stabilizers are also required because high temperatures necessary during manufacturing processes cause unadulterated PVC to break down (8,9). Lead additives have therefore been used to protect the miniblinds from ultraviolet light and heat (10). Today, most U.S. manufacturers use tin and antimony additives rather than lead stabilizers to guard against the degradation of plastic (8).

While additives prevent the breakdown of the plastic, degradation still can occur. If the lead additives are not compatible with other agents used in formulating the PVC, chemical and physical reactions between the additives may cause breakdown. Lead can then migrate to the surface of the blinds and become available as particulates (9). The dislodgeable lead dust that forms on the miniblinds after they have been exposed to heat and light in windows therefore presents a hazard to small children who engage in hand-to-mouth behavior after handling these miniblinds (4).

Conclusion

Over the last 20 years, children's blood lead levels have been reduced through the actions of federal and state agencies that have banned residential use of lead-based paint, lead solder in plumbing and food cans, and leaded gasoline. Nevertheless, children continue to be exposed to environmental sources of lead. Public health agencies must continue to provide communities with childhood lead-poisoning intervention programs and must remain alert to unusual or new lead sources (1). Physicians who screen patients for lead exposure may wish to include a question about exposure to plastic miniblinds; the exposure of young children to lead dust from miniblinds crosses the socioeconomic barriers often associated with childhood lead poisoning cases.

ADHS and CPSC have recommended to parents of small children that imported miniblinds be removed from their homes. Lead dust accumulating from the blinds on windowsills, walls, and floors may be wiped away with common household detergents. Reformulated miniblinds without lead additives became available in retail stores nationwide in July 1996.

REFERENCES

1. Centers for Disease Control and Prevention (1991) Preventing Lead Poisoning in Young Children: A Statement by the Centers for Disease Control, Atlanta, Ga.: U.S. Department of Health and Human Services, Public Health Service, pp. 3-4.

2. Arizona Revised Statutes (1975), Phoenix, Ariz., [section] 36-1611.

3. Consumer Reports (September 1996), Safety Alert - Miniblinds May Be Hazardous to Kids, Washington, D.C.: Office of Information and Public Affairs.

4. U.S. Consumer Product Safety Commission (June 25, 1996), Press Release #96-150, Washington, D.C.: Office of Information and Public Affairs.

5. U.S. Environmental Protection Agency (1995), Sampling House Dust for Lead. EPA 747-R-95-007, Washington, D.C.: Office of Prevention, Pesticides and Toxic Substances, pp. 3-5.

6. Arizona Department of Health Services (December 7, 1995), Press Release, Phoenix. Ariz.: Office of the Director.

7. North Carolina Department of Environment, Health, and Natural Resources (March 4, 1996), Press Release 3/4/96a, Raleigh, N.C.: Public Affairs Office.

8. Edenbaum, J., ed. (1992), Plastics Additives and Modifiers Handbook, New York: Van Nostrand Reinhold, pp. 6, 331-337.

9. Chemical Additives for Plastics Industry: Properties, Applications, Toxicologies (1987), Park Ridge, N.J.: Radian Corporation, Noyes Data Corporation, p. 92.

10. Office of Lead-based Paint Abatement and Poisoning Prevention (August 23, 1996), Technical Bulletin Addressing the Exposure Hazard from Lead in Imported Vinyl Miniblinds, Washington, D.C.: U.S. Department of Housing and Urban Development.

Corresponding Author: Kristina E. Schaller, Arizona Department of Health Services, Office of Environmental Health, 3815 North Black Canyon Highway, Phoenix, AZ 85015. E-mail: <[e-mail]>. ance at any l