Agency for Toxic Substances and Disease Registry
Case Studies in Environmental Medicine (CSEM) 

Lead Toxicity
What Are the U.S. Standards for Lead Levels?

Learning Objectives

Upon completion of this section, you will be able to

• identify the CDC’s level of concern for lead in children’s blood
• identify the OSHA blood lead level for first intervention from occupational exposure to lead
• describe the types of environmental standards in the U.S.

Introduction

Because of lead’s importance as a cause of public health problems, a number of federal agencies have issued advisory standards or enforceable regulations that set lead levels in different media. The table below summarizes these standards and regulations for 2006; see subsequent sections for further explanation.

Biologic Guidelines

As new information has emerged about the neurological, reproductive, and possible hypertensive toxicity of lead, and as parameters that are more sensitive are developed, the BLLs of concern for lead exposure have been progressively lowered by CDC. (See Figure 1 below).

Figure 1. Lowering of CDC-recommended action level for blood lead in children over time.

Ten µg/dL (micrograms /deciliter) was adopted by CDC in 1991 as an action level for children, an advisory level for environmental and educational intervention.

• CDC case management guidelines are designed to keep children’s BLLs below 10 µg/dL (CDC, 2002).
• There are also requirements that children receiving Medicaid be screened.
• Studies have found neurobehavioral impairment in children with BLLs below 10 µg/dL. (Canfield, 2003; Lanphear et al. 2000)
• No blood lead threshold has been identified in children.

The Biological Exposure Index (BEI) is a guidance value for assessing biological monitoring results.

The BEI for blood lead is 30 µg/dL. (ACGIH 2005)

The BEI indicates exposure at the Threshold Limit Value (TLV) (See “Workplace Air” below).

Physician Reporting Requirements

Most states ask or require primary care physicians and persons in charge of screening programs to report both presumptive and confirmed cases of lead toxicity to the appropriate health agency. This is to ensure

• abatement of the lead source
• education of the patient
• remediation steps are undertaken

In some states, the clinical laboratories performing blood lead testing are required to report cases of lead toxicity.

Even if not required, a physician should strongly consider consulting a health agency in the case of lead toxicity, as health agencies are important sources of resources and information.

In some states, laboratories performing BLL or EP (ZPP) tests are also required to report abnormal results to the appropriate health agency.

Workplace Air

The OSHA Lead Standard specifies the permissible exposure limit (PEL) of lead in the workplace, the frequency and extent of medical monitoring, and other responsibilities of the employer.

OSHA has set a PEL (enforceable) of lead in workplace air at 50 µg/m³ averaged over an 8-hour workday for workers in general industry.

• For those exposed to air concentrations at or above the action level of 30 µg/m³ for more than 30 days per year, OSHA mandates periodic determination of BLLs.
• If a BLL is found to be greater than 40 µg/dL, the worker must be notified in writing and provided with a medical examination.
• If a worker's one-time BLL reaches 60 µg/dL (or averages 50 µg/dL or more on three or more tests), the employer is obligated to remove the employee from excessive exposure, with maintenance of seniority and pay, until the employee's BLL falls below 40 µg/dL.

A copy of the lead standard can be obtained by calling your regional office of OSHA or from the CFR website (www.gpoaccess.gov/cfr/index.html).

NIOSH at CDC has set a Recommended Exposure Limit (REL) of 50 µg/m³ to be maintained so that worker blood lead remains < 60 µg/dL of whole blood. http://www.cdc.gov/niosh/npg/npgd0368.html.

The ACGIH has set a threshold limit value for a time-weighted average (TLV/TWA) of 50 µg/m³ for lead in workplace air (except for lead arsenate). http://www.acgih.org/home.htm.

Soil

Lead contaminated soil can pose a risk through direct ingestion, uptake in vegetable gardens, or tracking into homes.

• Uncontaminated soil contains lead concentrations less than 50 ppm but soil lead levels in many urban areas exceed 200 ppm. (AAP 1993)
• The EPA’s standard for lead in bare soil in play areas is 400 ppm by weight and 1200 ppm for non-play areas. This regulation applies to cleanup projects using federal funds.

The soil screening level (SSL) for lead represents a conservative estimate for a level that would be protective of public health in residential soils based on an analysis of the direct ingestion pathway for children. This value is for guidance only and is not enforceable.

Drinking Water

EPA has set drinking water standards with two levels of protection.

• The maximum contaminant level goal (MCLG) is zero. This is the levels determined to be safe by toxicological and biomedical considerations, independent of feasibility.
• EPA’s final rule establishes an action level is set at 15 µg/L.

For further information, call the EPA Safe Drinking Water Hotline toll-free at 1-800-426-4791. http://www.epa.gov/safewater/

The use of lead solder and other lead-containing materials in connecting household plumbing to public water supplies was banned by EPA as of June 1988.

• Many older structures, however, still have lead pipe or lead-soldered plumbing internally, which may substantially increase the lead content of water at the tap.
• Regulations controlling the lead content of drinking-water coolers in schools went into effect in 1989.
• Residents can buy inexpensive drinking water lead screening kits (see www.afhh.org) or hire professionals to test their water.

Food

FDA has set a number of action levels (enforceable) and levels of concern for lead in various food items. These levels are based on FDA calculations of the amount of lead a person can consume without ill affect.

• For example, FDA has set an action level of 0.5 µg/mL for lead in products intended for use by infants and children and has banned the use of lead-soldered food cans. (FDA 1994 and FDA 1995 as cited in ATSDR 1999)

Paint

White house paint contained up to 50% lead before 1955. Federal law lowered the amount of lead allowable in paint to 1% in 1971. The CPSC has limited since 1977 the lead in most paints to 0.06% (600 ppm by dry weight). Paint for bridges and marine use may contain greater amounts of lead.

Advisory; level for individual management

Regulation; cause for written notification and medical exam
Regulation; cause for medical removal from exposure

Advisory; indicates exposure at the threshold limit value (TLV)

Regulation; PEL (8-hr average.) (general industry)
Action level

REL (non-enforceable)

TLV/TWA guideline for lead arsenate
TLV/TWA guideline for other forms of lead

Regulation; NAAQS; 3-month average

Soil screening guidance level; requirement for federally funded projects only (40 CFR Part 745, 2001)

Action level for public supplies
Non-enforceable goal; MCLG

Action levels for various foods; example: lead-soldered food cans now banned

Regulation; by dry weight. There is a new standard for lead in children’s jewelry.

Key Points

• CDC lowered the recommended blood lead action level for lead exposure in children to10 µg/dL in 1991.
• States may have their own levels of concern for adults and children.
• Most states have reporting systems for lead poisoning.
• OSHA has set required standards for the amount of lead allowed in workroom air at 50 µg/m³ averaged over an 8-hour workday.
• EPA has set a standard for lead in the ambient air of 1.5 µg/m³ averaged over a calendar quarter.
• EPA has established 400 ppm for lead in bare soils in play areas and 1200 ppm for non-play areas for federally funded projects. This may be used as a guidance level elsewhere.
• EPA's action level for lead in water delivered to users of public drinking water systems is 15 µg/L. Its goal for lead is zero.
• FDA has set various action levels regarding lead in food items. Use of lead-soldered food cans is now banned.
• Today, paint intended for residential use is limited to 0.06% lead content.

Progress Check

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