Unintentional Topical Lindane Ingestions --- United States, 1998--2003

Lindane* is an organochlorine pesticide found in certain prescription-only shampoos and topical lotions used to treat pediculosis (i.e., lice infestation) and scabies; lindane has been associated with human neurologic toxicity (1,2). In 2004, CDC was alerted to cases of illness caused by unintentional ingestion of lindane by persons mistaking the product for a liquid oral medication (e.g., cough syrup). To assess the extent of illness from ingestion of lindane, CDC, with assistance from the U.S. Environmental Protection Agency, Food and Drug Administration (FDA), and state health departments, collected case reports and analyzed data from the Sentinel Event Notification System for Occupational Risks-Pesticides (SENSOR-Pesticides) program and the Toxic Exposure Surveillance System (TESS). This report summarizes the results of that analysis, which identified 870 cases of unintentional lindane ingestion during 1998--2003, and describes two examples of lindane ingestions. To reduce the risk of lindane ingestion, public health authorities should alert clinicians to the hazards of lindane and the importance of following FDA usage guidelines, which include dispensing lindane in manufacturer-produced, 1- or 2-ounce single-use containers.

Case Reports

Case 1. In November 2004, the Washington State Department of Health reported that a boy aged 3 years ingested approximately 1 teaspoon of 1% lindane shampoo from a previously used 2-ounce bottle. Subsequently, the mother induced vomiting in the boy twice; 1 hour later the boy collapsed and experienced a tonic-clonic seizure lasting 4--5 minutes. After 3 hours, the child was discharged from the emergency department in stable condition.

Case 2. In December 2003, a man aged 47 years in Texas mistakenly ingested 1 ounce of lindane (percentage concentration unknown) from a bottle he believed to be cough syrup. The man vomited; he contacted the poison control center the following morning. He did not seek clinical evaluation.

Surveillance Data

Data were analyzed from pesticide poisoning surveillance systems participating in the SENSOR-Pesticides program^† to identify symptomatic cases involving unintentional topical lindane ingestions during 1998--2003. Cases were classified as definite, probable, possible, or suspicious based on the clinical interpretation of signs or symptoms reported by a physician or patient, and evidence of lindane ingestion (3,4). Cases were also obtained from TESS^§, which is maintained by the American Association of Poison Control Centers; poison information specialists determined which cases had signs and symptoms consistent with lindane exposure. Illness severity was categorized for all cases. Excluded were cases involving ingestion of veterinary and agricultural pesticide products that contained lindane.

During 1998--2003, TESS reported 857 symptomatic cases of unintentional lindane ingestion (Figure); none of the cases were reported as resulting in death. Severity was low in 778 cases (91%), moderate in 71 cases (8%), and high in eight cases (1%) (4). Among 823 patients with known ages, median age was 13 years (range: <1--86 years); 53% were female. Signs and symptoms included vomiting (59%), nausea (18%), oral irritation (19%), abdominal cramping (4%), cough (4%), and seizure (3%).

During 1998--2003, SENSOR-Pesticides identified a total of 13 symptomatic cases of unintentional lindane ingestion. Four cases (31%) were classified as definite, two (15%) as probable, six (46%) as possible, and one (8%) as suspicious. Severity was low in eight cases (62%), moderate in three cases (23%), and high in two cases (15%) (3). Median age was 7 years (range: <1--58 years), and 69% were male. Signs and symptoms included vomiting (69%), nausea (46%), headache (23%), seizure (23%), abdominal cramping (8%), and confusion (8%). Six (46%) cases in children and four (31%) cases in adults were the result of mistaking lindane for cough syrup; two (15%) cases were in unsupervised children who drank lindane, and one (8%) case was the result of pharmacy error (i.e., lindane was recovered from a bottle labeled albuterol).

In addition to lindane, FDA-approved treatments for pediculosis include two over-the-counter medications (pyrethrin/piperonyl butoxide and permethrin) and malathion, a prescription-only therapy. During 1998--2003, TESS identified 523 symptomatic cases of unintentional ingestion of these alternative medications (Figure). Median age was 9 years (range: <1--67 years). Among TESS reports, unintentional lindane ingestions were more likely to produce illness (857 illnesses of 1,463 ingestions [58%]) than unintentional ingestions of each of three other medications, and more likely to produce illness than all three of those medications combined (523 illnesses of 1,691 ingestions [31%]; odds ratio = 3.16, 95% confidence interval = 2.72--3.67).

Reported by: J Sievert, Texas Dept of State Health Svcs. M Lackovic, MPH, Louisiana Dept of Health and Hospitals. A Becker, PhD, Florida Dept of Health. DH Lew, Oregon Dept of Human Svcs. B Morrissey, Washington State Dept of Health. J Blondell, PhD, Office of Pesticide Programs, US Environmental Protection Agency. LY Kim-Jung, PharmD, MR Pitts, PharmD, CA Holquist RPh, Food and Drug Admin. AM Petersen, MPH, JS Alonso-Katzowitz, GM Calvert, MD, Div of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, CDC.

Editorial Note:

Pediculosis and scabies are common human parasitic infestations. This report indicates that when lindane, a treatment for pediculosis and scabies, is unintentionally ingested, illness can occur, including vomiting and seizures. In 1995, lindane was changed to a second-line therapy for pediculosis because safer alternatives existed (5). Lindane also had the slowest pediculicidal and least effective ovicidal activity compared with three other approved pediculicides (i.e., 1% permethrin, 0.3% pyrethrin, and 0.5% malathion) (6). In 2003, in light of continued postmarketing surveillance reports of toxicity, FDA revised product labeling guidelines to limit the amount of lindane dispensed to 1- or 2-ounce single-use containers and to require providing patients with a Medication Guide warning of risks from inappropriate use. In addition, FDA issued a Public Health Advisory with these changes (7). The new advisory, along with a substantial increase in retail price for lindane, appear to have resulted in a declining number of cases of lindane ingestion (Figure). This decline is similar to the 67% decrease in lindane prescriptions from 1998 to 2003 (8).

Before the advisory, bottles of bulk lindane were sometimes repackaged by pharmacies into smaller bottles resembling those used for liquid oral medications (e.g., cough syrup). This resemblance likely contributed to many unintentional ingestions. Subsequent to the advisory, bottles of bulk lindane still in use were not recalled from pharmacies. Therefore, some repackaging might still occur. In addition, consumers might have repackaged lindane in their homes.

In September 2004, the North American Task Force on Lindane drafted an action plan for future use. On January 1, 2005, Canada withdrew registration of lindane for agricultural pest control; Mexico is working on a plan to phase out all uses of lindane. However, with the exception of California, which banned lindane for medicinal use on January 1, 2002, U.S. representatives to the North American Commission for Environmental Cooperation announced that the United States will continue to allow use of lindane as both a pesticide and pharmaceutical (9).

The findings in this report are subject to at least three limitations. First, because of the passive surveillance methodology of TESS and SENSOR, the number of reported cases is likely fewer than the number of actual cases. Second, certain eligible cases might have been inadvertently excluded because of erroneous information that suggested exposure to lindane in a veterinary or agricultural product. Finally, although all cases were symptomatic, the possibility of false positives cannot be excluded. Because clinical findings of lindane poisoning are nonspecific and no standard diagnostic test exists, certain illnesses related temporally to lindane exposure might not have been caused by the exposure.

Lindane use in shampoos and lotions for treatment of pediculosis and scabies is declining. However, because of the toxicity of lindane and the potential for illness from unintentional ingestion, health-care providers should be educated regarding appropriate use and packaging. Lindane is a second-line therapy for both scabies and lice and should not be tried unless other treatments have failed or are intolerable; use of lindane also should be avoided for persons weighing less than 110 pounds (50 kg). Because of the risk for toxicity, treatment should not be repeated, even if itching persists; itching can occur, even after successful treatment (especially for scabies) and can be treated symptomatically. In addition, pharmacists should not transfer lindane to other containers and should only dispense lindane in manufacturer-provided 1- or 2-ounce containers. Finally, periodic educational outreach programs can help increase awareness among health-care providers of the new lindane use guidelines.

References

1. Tenenbein M. Seizures after lindane therapy. J Am Geriatr Soc 1991;39:394--5.
2. Fischer TF. Lindane toxicity in a 24-year-old woman. Ann Emerg Med 1994;24:972--4.
3. Calvert GM, Plate DK, Das R, et al. Acute occupational pesticide-related illness in the US, 1998--1999: surveillance findings from the SENSOR-Pesticides program. Am J Ind Med 2004;45:14--23.
4. Calvert GM, Sanderson WT, Barnett M, Blondell JM, Mehler LN. Surveillance of pesticide-related illness and injury in humans. In: Krieger R, ed. Handbook of pesticide toxicology. 2nd ed. San Diego, CA: Academic Press; 2001.
5. Roberts RJ. Clinical practice: head lice. N Engl J Med 2002;346:1645--50.
6. Meinking TL, Entzel P, Villar ME, Vicaria M, Lemard GA, Porcelain SL. Comparative efficacy of treatments for pediculosis capititis infestations: update 2000. Arch Dermatol 2001;137:287--92.
7. Center for Drug Evaluation and Research, Food and Drug Administration. Lindane shampoo and lindane lotion. Rockville, MD: Food and Drug Administration; 2003. Available at http://www.fda.gov/cder/drug/infopage/lindane/default.htm.
8. IMS Health. National Prescription Audit Plus™. Plymouth Meeting, PA: IMS Health; 2005.
9. North American Commission for Environmental Cooperation. Mexico to eliminate toxic chemical lindane. Montreal, Canada: North American Commission for Environmental Cooperation; 2004. Available at http://www.cec.org/news/details/index.cfm?varlan=english&ID=2631.

* Lindane is also referred to as gamma-hexachlorocyclohexane.

^† SENSOR-Pesticides is a surveillance program coordinated by the National Institute for Occupational Safety and Health (NIOSH) at CDC and conducted by health departments in nine states. Most participating states collect information on both nonoccupational and occupational pesticide poisonings from various sources (e.g., poison control centers, workers' compensation agencies, or state departments of agriculture). However, priority is given to occupational cases; therefore, the number of nonoccupational poisoning cases is limited.

^§ TESS receives reports from nearly all poison control centers nationwide.

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Date last reviewed: 6/2/2005