Lead Poisoning in Children: Early Detection, Intervention and Prevention
Part I: Disease and Epidemiology
When lead enters the body it is absorbed and then stored for long periods in mineralizing tissue such as teeth and bones and then released again into the bloodstream, especially in times of bodily stress, such as pregnancy, breastfeeding, calcium deficiency, or osteoporosis.
Definition of Lead Poisoning
Elevated Blood Lead Levels (EBLL), or lead poisoning (also known as saturnism, plumbism, Devon colic, or painter's colic) is a medical condition caused by increased levels of the metal lead in the blood.
EBLL may cause irreversible
- neurological damage
- renal disease
- cardiovascular effects
- reproductive toxicity
Humans have been mining and using this heavy metal for thousands of years, poisoning themselves in the process due to accumulation and exposure. These dangers have long been known, though the modern understanding of their full extent and the small amount of lead necessary to produce them is relatively recent; blood lead levels once considered safe are now considered hazardous, with no known threshold.
Description of the Disease of Lead Poisoning
Lead is primarily ingested or inhaled. The most common source of lead exposure is ingestion of lead containing dust. The rate of lead uptake is affected by the individual's developmental stage, the route of exposure, and the nature of the lead [compounds] to which the individual is exposed. Nutritional status is also important: a healthy diet high in iron and calcium and low in fat, for example, may slow the rate of lead absorption.
According to the Agency for Toxic Substances and Disease Registry (ATSDR), absorption depends on the form of the lead. Inhaled, airborne lead is almost totally absorbed, while ingested lead absorption rates may vary from 10% in adults to 50% in children. Lead is absorbed more efficiently in dust from sanded lead-based paint than from whole paint chips. The most dangerous exposure is to lead vapors (formed whenever lead is melted) or other inhalable lead compounds. Absorbed lead is detectable in blood, soft tissue and bone. The half-life of lead varies from about one month in blood, 1-1.5 months in soft tissue, to about 25-30 years in bone.
As of summer 2012, EBLL or lead poisoning is defined by the CDC as a blood lead level of 5 mcg/dL or greater, which represents the top 2.5% of children whose blood lead levels were tested. This is now the level at which both the CDC and MDH recommend taking action.
Lead Poisoning: Acute and Chronic Disease
The disease of lead poisoning can be divided into acute disease referring to current EBLLs and chronic disease referring to the cumulative effects of EBLLs on the body lead level. In both acute and chronic disease the most prominent signs and symptoms are neurological-for children this may lead to permanent neurological effects.
Children with very high BLLs (≥60 mcg /dL) should be treated as medical emergencies, regardless of whether or not the child displays symptoms. Ingestion of a metallic object that may contain lead can result in an EBLL within hours. Any child that has ingested a metallic object that may contain lead should receive immediate medical attention including a blood lead test and abdominal x-ray.
Lead Poisoning: Acute Disease
Acute exposure to lead generally means exposure for a short time, but at high levels. The following are symptoms of acute exposure but are seldom caused by EBLLs <50 mcg/dL.
- most common = intermittent abdominal pain
- constipation or diarrhea
- muscle pain
In more severe cases, warning signs of acute, serious brain swelling include:
- extreme irritability
- progressive drowsiness.
These symptoms may be warnings of even more serious symptoms to follow:
- possibly death
The EBLLs associated with encephalopathy in children vary from study to study, but BLLs of 70-80 mcg/dL or greater appear to indicate a serious risk (ATSDR 2010).
An example of acute disease occurred in 2006
A Minnesota child died as a result of swallowing a lead-containing bracelet that came with a pair of shoes.
This case study can be found at: http://www.cdc.gov/mmwr/PDF/wk/mm55d323.pdf (PDF)
Lead Poisoning: Chronic Disease
Chronic lead exposure generally means exposure to low to moderate levels of lead over a long period of time. Recent studies confirm that lead absorption is harmful at any concentration. Relatively low blood lead levels rarely cause noticeable signs and symptoms, but can cause permanent damage-especially in young children-including but not limited to:
- decreased IQ
- developmental delays
- other behavioral disturbances.
A study of US adolescents published in the Archives of Internal Medicine, in January 2010 not only showed that there were long lasting effects of lead poisoning (decreased kidney function) but that these effects were noted in adolescents whose EBLLs were less than 10 mcg/Dl (Fadrowski et al, 2010).
Due to the numerous adverse effects of EBLLs, the government requires that blood lead testing be done at 12 and again at 24 months for children enrolled in MA or MinnesotaCare.
The following web page provides additional resources for lead in English and Spanish as well as other lead related information.
Sources of Lead in the Environment
Lead was used in common house paint until 1978 when the Consumer Product Safety Commission (CPSC) restricted its use in household paint. Many buildings built before 1978 have lead-based paint inside and outside.
Housing built before 1950 is at even greater risk of having interior lead-based paint, the older the building, the more likely it is to contain lead paint.
Chipping, peeling or chalking lead paint is a common source of ingestible lead dust and creates a strong potential for lead exposure.
Lead paint dust is the most common source of lead exposure for children. Lead as dust is much more easily absorbed. Interior house dust can become contaminated with lead as the result of the deterioration or disturbance of leaded paint. Fine lead dust, and resulting contamination, can be created when painted surfaces rub against each other, such as where double hung windows slide up and down or when doors open and close. Lead in dust is increased after older paint has been disturbed through remodeling, renovation or repainting. Additionally, people track in contaminated soil on their shoes and/or clothing, and the fallout of airborne lead particles from industrial or vehicular sources and can create contaminated dust.
Occupational Exposures or "Secondary Transmission"
Household contacts of persons with occupational, vocational, or other exposures may be exposed to lead dust or other compounds brought in to the home. Some of the occupations that carry a potential for exposure to lead include:
- building demolition
- battery recycling
- radiator repair
- bridge construction
People who work in a lead environment may bring lead dust into their car or home on their clothes and bodies and unintentionally expose their family.
Proper hygiene practices such as washing or showering and changing out of work clothes before leaving for home will eliminate or at the least substantially decrease the amount of lead dust brought into the home.
Folk Medicines and Cosmetics
Many home remedies popular in some ethnic communities may contain lead. Medications may be as much as 90% lead by weight and include:
- Greta, Alarcon, Rueda and Azarcon, used for gastro-intestinal disturbances in the Latino community (empacho)
- "Pay-loo-ah," used by many Southeast Asians.
- Cosmetic products are a primary source of lead in Asian and Arab countries
- Applying Kohl results in lead exposure primarily via hand-to-eye-to-mouth activities and subsequent ingestion of particles
Many hobbies involve lead use such as:
- making or handling lead buckshot/bullets
- fishing weights/sinkers
- toy soldiers
- stained glass solder
- ceramic glazing
Heating and melting lead is particularly dangerous because of the formation of lead vapor, so respirator use and proper ventilation are required to prevent exposure.
Other hobbies that carry a potential for exposure to lead include:
- furniture refinishing
- auto or boat repair
- home remodeling
- target shooting at firing ranges
Hobbyists can protect their families by keeping the hobby activity away from living areas and by showering or changing clothes before entering the home.
Lead may be found in the following dishes, glasses, and pottery:
- poorly glazed ceramic dishes and pottery (in particular chipped, Imported, old, or handmade)
- leaded crystal
In these pieces, acid substances may interact chemically with the glaze and accelerate the lead release. Therefore, acidic foods (such as orange, tomato and other fruit juices, tomato sauces, wines, and vinegar) stored in improperly glazed containers are potentially the most dangerous.
If it is not known whether or not a particular tableware item contains lead, the item should not be used to store, cook or serve food or beverages.
Most well or city water does not naturally contain lead although some old well pumps still in operation may have the potential for contaminating the well with lead.
In homes where older plumbing has not been updated, lead pipes can be a source of water contamination. Lead leaches into drinking water from these lead pipes as well as brass faucets and lead solder that connects the pipes.
Hot water is particularly corrosive and should not be used for drinking, cooking, or preparing infant formula.
The cold-water tap should be flushed for several minutes each morning or after sitting until there is a noticeable change in temperature of the water before any water is consumed.
Lead solder is no longer used in the processing of canned foods in the United States dramatically reducing lead in food. However, imported food products may still contain lead as some foreign manufacturers use lead solder in cans. Some imported food products that are sold in ethnic markets, at swap meets, and by door-to-door vendors may contain high levels of lead.
Food may also be contaminated with lead from the soil or use of lead-based pesticides in the growing process.
In recent years, lead has been found in candy imported from countries such as Mexico. The lead ink from the paper wrapper contaminates the candy, especially if these products are acidic tamarind and tejocote fruit.
There continues to be an ever-increasing array of household products that contain lead, especially imported products.
In recent years, lead has been found in:
- vinyl miniblinds
- curtain weights
- calcium supplements
- hair dyes
- children's jewelry and toys
- Christmas tree lights
Ingestion of any object that may contain lead should be treated as a medical emergency and treatment should include a blood lead test and abdominal x-ray.
Go To >> Part II: Screening Guidelines