Introduction

Because lead causes significant public health problems, a number of federal agencies have issued advisory standards or enforceable regulations that set lead levels in different media. Table 4: Standards and Regulations for Lead, below summarizes these standards and regulations [ACCLPP 2012]; see subsequent sections for further explanation.

Although reductions in lead exposure for the U.S. population have resulted in lower blood lead levels (BLLs) over time, epidemiological studies continue to provide evidence of health effects at increasingly lower BLLs [AAP 2016, NTP 2012].

Figure 2. Lowering of BLLs Considered Elevated by CDC Over Time

The National Toxicology Program [2012] concludes that there is sufficient evidence for adverse health effects in children and adults at BLL <5 µg/dL [CDC 2012].

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, BLLs previously thought to be "safe" have been demonstrated to cause adverse health outcomes.

Five micrograms per deciliter (μg/dL) was adopted by CDC in 2012 as the upper reference range value for BLLs in children as an advisory level for environmental and educational intervention [ACCLPP 2012].

• Primary prevention strategies should be designed to keep children's BLLs below 5 (μg/dL [ACCLPP 2012].
• Children receiving Medicaid are required to be screened.
• No blood lead threshold for adverse health effects has been identified in children, and no BLL above zero is free of all risk.
• At lower concentrations of lead in the blood - below 10 μg/dL -children tested for IQ at ages three and five, showed a greater decline in IQ for a rise in blood lead from 1 to 10 μg/dL, than those whose blood lead level went from 10 to 20 μg/dL [Canfield et al. 2003].

Experts now use an upper reference level value of 97.5% of the population distribution for children's blood lead, based on the National Health and Nutrition Examination Survey (NHANES) estimate of the distribution of BLLs in children ages 1-5 years. In 2012-2015, the value to identify children with blood lead levels that are much higher than most children have, is 5 micrograms per deciliter (5 μg/dL) [ACCLPP 2012].

The National Toxicology Program [2012] concludes that there is sufficient evidence for adverse health effects in children and adults at BLL <5 μg/dL [CDC 2012].

The American Conference of Industrial Hygienists (ACGIH) develops Biological Exposure Indices (BEI) as guidance values for assessing biological monitoring results in occupational settings by individuals trained in the discipline of industrial hygiene to assist in the control of potential workplace health hazards and for no other use. These values are not fine lines between safe and dangerous concentrations and should not be used by individuals without training in the discipline of industrial hygiene.

Physician Reporting Requirements

Most states ask or require primary care physicians and/or laboratories to report all BLLs to the appropriate health agency. This is to ensure

• Abatement (removal) of the lead source,
• Education of the patient, parent/family,
• Remediation (corrective) steps are taken, and
• Targeting public health activities to areas with highest risk.

Physicians should strongly consider consulting a health agency, such as the local health department, or poison control center, in cases of lead toxicity.

Workplace Air

The OSHA Lead Standard applies to all workers in general industries, shipyards, and in construction industries where an employee may be occupationally exposed to lead [OSHA 2012a OSHA 2012b OSHA 2012c].

Action level means employee exposure, without regard to the use of respirators, to an airborne concentration of lead of 30 micrograms per cubic meter of air (30 µg/m³) calculated as an 8-hour time-weighted average (TWA).

• OSHA set a Permissible Exposure Limit (PEL) for lead in workplace air of 50 µg/m³ (8-hour time weighted average).
• OSHA mandates periodic determination of BLL for those exposed to air concentrations at or above the action level of 30 µg/m³ for more than 30 days per year.
• The worker must be notified in writing within 15 days after the receipt of the results or any monitoring performed, and provided with a medical examination if a BLL is found to be greater than 40 µg/dL.
• 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 if a worker's one-time BLL reaches 60 µg/dL (or averages 50 µg/dL or more on three or more tests) in general industries or shipyards, or 50 µg/dL in construction.

The current Code of Federal Regulations standards for lead may be accessed at:
https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10030.
https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10641.
https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10318.

States can have more protective standards than federal OSHA, e.g., California.

The National Institute of Occupational Safety and Health (NIOSH) at CDC has set a Recommended Exposure Limit (REL) of 50 µg/m³ for a Time Weighted Average (TWA) of 8 hours to be maintained so that worker blood lead remains <60 µg/dL of whole blood. The REL can be accessed at:
https://www.cdc.gov/niosh/npg/npgd0368.html.

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). This can be accessed at: http://www.acgih.org/

ACGIH has set a Biological Exposure Indices (BEI) for blood lead at 30 µg/dL.

As previously mentioned, ACGIH's BEI and TLV values are intended for use in the practice of industrial hygiene as guidelines or recommendations to assist in the control of potential workplace health hazards and for no other use. These values are not fine lines between safe and dangerous concentrations and should not be used by individuals without training in the discipline of industrial hygiene.

CDC [2010] recommends a precautionary approach, noting that a BLL ≥5 µg/dL in a pregnant woman indicates that she has or has had exposure to lead well above that for most women of child bearing age in the United States. For occupationally exposed pregnant women, the recommendation is to keep BLLs as low as possible and to remove pregnant women from lead-exposed work areas if BLLs are ≥10 µg/dL [CDC 2010].

CDC/NIOSH reference BLL for adults is 5 µg/dL [CDC 2013h].

Soil

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

• Soil contains lead concentrations less than 50 parts per million (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 [EPA 2000a]. 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

The Lead and Copper Rule (also referred to as the LCR) is an EPA regulation to control lead and copper in drinking water. Lead and copper enter drinking water primarily through plumbing materials. Exposure to lead and copper may cause health problems ranging from stomach distress to brain damage.

The LCR was established in 1991, and has undergone various revisions. It has four basic requirements:

1. Require water suppliers to optimize their treatment system to control corrosion in customer's plumbing;
2. Determine tap water levels of lead and copper for customers who have lead service lines or lead-based solder in their plumbing system;
3. Rule out the source water as a source of significant lead levels; and,
4. If lead action levels are exceeded, require the suppliers to educate their customers about lead and suggest actions they can take to reduce their exposure to lead through public notices and public education programs.

The EPA Lead and Copper Rule has set drinking water standards with two levels of protection [EPA 1991; EPA 2000b].

• Action levels for lead of 15 ppb and copper of 1.3 ppm in more than 10% of customer taps sampled. An action level is the level for enforcement.
• The maximum contaminant level goal (MCLG) is zero. This is the level determined to be safe according to toxicological and biomedical considerations, independent of feasibility.

"If a water system, after installing and optimizing corrosion control treatment, continues to fail to meet the lead action level, it must begin replacing the lead service lines under its ownership" [EPA 2007].

Exceeding the action level alone is not a violation of the regulation. Public water systems are assigned a violation when they fail to perform actions required by the regulations. This happens after the action level is exceeded [EPA 2000b; EPA 2016b].

The use of lead solder and other lead-containing materials in connecting household plumbing to public water supplies was banned by EPA in June of 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 or hire professionals to test their water. For further information, call the EPA Safe Drinking Water Hotline toll-free at 1-800-426-4791 or visit https://www.epa.gov/safewater/.

The U.S. Food and Drug Administration (FDA) level for bottled water is 5 ppb [FDA 2009].

Food

The 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 [FDA 2014, 1995, and 1994].

For example, FDA has set an action level of 0.5 μg/dL for lead in in food products intended for use by infants and children and has banned the use of lead-soldered food cans [FDA 1994].

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. In 1977, the Consumer Products Safety Commission limited the lead in most paints to 0.06% (600 ppm by dry weight). Since 2009, the lead allowable in most paints is now 0.009%. Paint for bridges and marine use may contain greater amounts of lead.

Summary Table

Table 4: Standards and Regulations for Lead [ACCLPP 2012]

ACGIH - American Council of Government and Industrial Hygienists
CDC - Centers for Disease Control and Prevention
CPSC - Consumer Products Safety Commission
EPA - Environmental Protection Agency
NIOSH - National Institute of Occupational Safety and Health
OSHA - Occupational Safety and Health Administration
BLL - Blood Lead Levels
MCLG - Maximum Contaminant Level Goal
NAAQS - National Ambient Air Quality Standards
PEL - Permissible Exposure Level
ppm - parts per million
REL - Recommended Exposure Limit
TLV/TWA - Threshold Limit Value/Time Weighted Average
µg/dL - micrograms per deciliter

^* Note: BEI and TLV values are intended for use in the practice of industrial hygiene as guidelines or recommendations to assist in the control of potential workplace health hazards and for no other use. These values are not fine lines between safe and dangerous concentrations and should not be used by anyone untrained in the discipline of industrial hygiene.

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