California Code of Regulations › Title 8 - Industrial Relations › Division 1 - Department of Industrial Relations › Chapter 4 - Division of Industrial Safety › Subchapter 7 - General Industry Safety Orders › Group 16 - Control of Hazardous Substances › Article 109 - Hazardous Substances and Processes › Appendix C to Section 5198 - Medical Surveillance Requirements

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
This appendix outlines the medical surveillance
						  provisions of the general industry standard for lead and provides further
						  information to the physician or other licensed health care professional (PLHCP)
						  regarding the examination and evaluation of employees exposed to lead.
Introduction
The primary purpose of the Occupational Safety and
						  Health Act of 1970 is to ensure, so far as possible, safe and healthful working
						  conditions for every working person. The occupational health standard for lead
						  is designed to protect employees exposed to inorganic lead including metallic
						  lead, all inorganic lead compounds and organic lead soaps.
Under this standard, occupational exposure to inorganic
						  lead is to be limited to an airborne concentration of 10
						  µg/m3 (micrograms per cubic meter) calculated
						  as an 8-hour time-weighted average (TWA). This permissible exposure limit (PEL)
						  must be achieved through a combination of engineering, work practice, and
						  administrative controls to the extent feasible. Where these controls are in
						  place but are found not to reduce employee exposures to or below the PEL, they
						  must be used nonetheless, and supplemented with respirators to meet the 10
						  µg/m3 exposure limit. Where a separate
						  engineering control air limit (SECAL) has been specified for particular
						  processes in lead acid battery manufacturing or recycling (see section
						  5198, Table 1 in subsection (e)
						  Compliance), the employer shall implement engineering and work practice
						  controls to reduce and maintain employee exposure at or below the SECAL, except
						  to the extent that the employer can demonstrate that such controls are not
						  feasible. Where these controls are in place but are found not to reduce
						  employee exposures to or below the PEL, they must be used nonetheless, and
						  supplemented with respirators to meet the 10
						  µg/m3 PEL.
The standard establishes an action level of 2
						  µg/m3 calculated as an 8-hour TWA. The action
						  level refers to employee exposure, without regard to the use of respirators.
						  The action level triggers several ancillary provisions of the standard such as
						  exposure monitoring, medical surveillance, a training program, and
						  signs.
The standard includes a classification for work with
						  lead that may result in significant employee exposure to airborne lead. In the
						  standard, this work is referred to as presumed significant lead work (PSLW).
						  PSLW includes altering or disturbing material that contains or is likely to
						  contain at least 0.5% lead by weight; and torch cutting any scrap metal. In the
						  standard, "altering or disturbing" means "subjecting to a process that may
						  result in the release of lead dust, lead mist, lead fume, or other lead
						  particles. Such processes include, but are not limited to, welding, torch
						  cutting, brazing, torch soldering, melting, pouring, spraying, cutting,
						  shredding, crushing, baling, grinding, polishing, machining, drilling,
						  scraping, sanding, abrading, sweeping, raking, and shoveling." Examples of
						  materials that are likely to contain at least 0.5% lead include scrap lead,
						  lead solder, lead bullet fragments and dust, lead sheeting, lead cable housing,
						  and lead billets. Because scrap metal is likely to contain lead, and it is not
						  easy to tell if there is lead in a piece of scrap metal, all torch cutting of
						  scrap metal is classified as PSLW.
There is an exception to what counts as PSLW. Altering
						  or disturbing material, or torch cutting any scrap metal, is not PSLW when the
						  total combined duration of lead exposure resulting from altering, disturbing,
						  and torch cutting is less than 8 hours during any 30-day period.
If the employee performs PSLW, the employer must
						  provide the employee with interim protection, until the employer conducts an
						  exposure assessment and determines actual employee exposure, as required under
						  subsection (d) of the lead standard. Interim protections include appropriate
						  respiratory protection, protective clothing and equipment, medical
						  surveillance, training and posted signs. Once an exposure assessment has been
						  completed, the employer must provide the employee with appropriate protections
						  based on their level of exposure to lead, as required by the standard.
The standard also provides for a program of medical
						  surveillance for employees as outlined in section I. This program consists of
						  initial blood lead testing and medical evaluation, along with periodic blood
						  lead testing and medical evaluation, to be performed on a schedule which is
						  defined by previous laboratory results, employee complaints or concerns, and
						  the clinical assessment of the examining PLHCP.
Section I of this appendix provides a detailed
						  description of the medical surveillance procedures including the required
						  frequency of blood lead testing and medical examination and consultation for
						  exposed employees, provisions for medical removal protection (MRP), the right
						  of the employee to a second medical opinion, and notification and recordkeeping
						  requirements of the PLHCP and the employer. Discussions of respirator use,
						  respirator monitoring, and Cal/OSHA's position on prophylactic chelation
						  therapy are also included in this section.
Section II discusses the toxic effects and clinical
						  manifestations of lead poisoning and effects of lead intoxication on the
						  cardiovascular, neurologic, renal, gastrointestinal, and hematologic systems.
						  The adverse effects on both male and female reproductive capacity and on the
						  fetus are also discussed.
Section III outlines the recommended medical evaluation
						  of the employee exposed to inorganic lead including details of the medical
						  history, physical examination, and recommended laboratory tests, which are
						  based on the toxic effects of lead as discussed in section II.
Section IV provides detailed information concerning the
						  laboratory tests available for the monitoring of exposed employees. Also
						  discussed are the relative value of each test and the limitations and
						  precautions which are necessary in the interpretation of laboratory
						  results.
I. Medical surveillance requirements for employees
						  exposed to inorganic lead.
A. Blood Lead Testing
Under the occupational health standard for inorganic
						  lead, blood lead testing is to be made available to employees when they are
						  assigned to work in which they may be exposed to lead at or above the action
						  level, and as interim protection, if they perform PSLW. There are two
						  exceptions to this requirement. The first exception is if the employee is not
						  exposed to lead at or above the action level for 30 or more days in any 12
						  consecutive months, and their exposure is not on any day above 10
						  µg/m3 as an 8-hour TWA, without regard to
						  respirator use, then blood lead testing is not required to be provided. The
						  second exception is if the employee is not exposed to lead at or above the
						  action level for 15 or more days in any 12 consecutive months, and their
						  exposure is not on any day above 20 µg/m3 as
						  an 8-hour TWA, without regard to respirator use, then blood lead testing is not
						  required to be provided.
Unless the employee's exposure to lead falls under one
						  of the exceptions described above, blood lead testing must be made available
						  prior to assignment to lead work, or as soon as possible thereafter. There is
						  an exception to this requirement. Blood lead testing is not required prior to
						  assignment to lead work if an employee had a blood lead test in the preceding
						  two months.
Additional blood lead testing under the standard must
						  be provided on the following schedule: at least every two months for the first
						  6 months after initial placement, and also for the 6 months after any change in
						  task resulting in higher exposure; and at least every 6 months thereafter. If
						  an employee's last blood lead level (BLL) was at or above 10 µg/dl but
						  below 20 µg/dl, the testing frequency must be at least every 2 months and
						  not reduced until two consecutive tests, taken at least 30 days apart, indicate
						  a BLL below 10 µg/dl. Blood lead testing then must be provided as
						  described in the schedule given at the start of this paragraph. For employees
						  whose last BLL was at or above 20 µg/dl or who are removed from exposure
						  to lead due to an elevated blood lead, a new BLL must be measured
						  monthly.
B. Medical Examination and Consultation
A medical examination and consultation performed under
						  the guidelines discussed in section III is to be made available to employees
						  when they are assigned to work in which they may be exposed to lead at or above
						  the action level, or perform PSLW and an exposure assessment has not been
						  completed. There are two exceptions to this requirement. The first exception is
						  if the employee is not exposed to lead at or above the action level for 30 or
						  more days in any 12 consecutive months, and their exposure on any day is not
						  above 10 µg/m3 as an 8-hour TWA, without
						  regard to respirator use, then medical exams and consultations are not required
						  to be provided. The second exception is if the employee is not exposed to lead
						  at or above the action level for 15 or more days in any 12 consecutive months,
						  and their exposure on any day is not above 20
						  µg/m3 as an 8-hour TWA, without regard to
						  respirator use, then medical exams and consultations are not required to be
						  provided.
Medical examinations and consultations must be made
						  available prior to assignment for the first time to an area where the
						  concentration of airborne lead may be at or above the action level. Medical
						  examinations and consultations must also be made on an annual basis if an
						  employee's BLL is 20 µg/dl or greater at any time during the preceding 12
						  months. This medical examination must be made available as soon as possible
						  upon receiving a blood lead test result of 20 µg/dl or greater if the
						  employee has not had a lead-specific medical examination in the last 12 months.
						  In addition, a medical examination must be provided as soon as possible after
						  notification by an employee that the employee has developed signs or symptoms
						  commonly associated with lead intoxication, that the employee desires medical
						  advice regarding lead exposure and the ability to procreate a healthy child, or
						  that the employee has demonstrated difficulty in breathing during a respirator
						  fit test or during respirator use. A medical examination is also to be made
						  available as soon as possible and then as medically appropriate to each
						  employee removed from exposure to lead due to elevated BLLs, as discussed in
						  the next section, or whose exposure to lead is otherwise limited or specially
						  protected pursuant to medical recommendations.
The requirements of section
						  5198 for the medical surveillance
						  of employees who are exposed to lead are summarized in Table 1.Table 1. Minimum
						  Requirements for Medical Surveillance.
A. Blood lead level (BLL) tests
								  required to be made available prior to assignment.
For employees:
Prior to assignment to work
								  where exposure to lead is or reasonably expected to be >= the action level
								  (2 µg/m3 as an 8-hour TWA); and
NOTE: BLL is not required prior
								  to assignment for an employee who:
is not exposed to lead >=
								  the action level for >= 30 days in any 12 consecutive months, and is not
								  exposed on any day above 10 µg/m3 as an 8-hour
								  TWA; or
is not exposed to lead >=
								  the action level for >= 15 days in any 12 consecutive months, and is not
								  exposed on any day above 20 µg/m3 as an 8-hour
								  TWA.
Prior to performing presumed
								  significant lead work (PSLW), and an exposure assessment has not been
								  completed.
Additionally, BLL is not
								  required prior to assignment if an employee had a blood lead test in the
								  preceding two months.
B. Additional BLL tests required to be made
								  available.
For employees:
whose last BLL was >= 10
								  µg/dl; or
who are exposed >=
								  action level; or
NOTE: additional BLLs are not
								  required for an employee who:
is not exposed to lead >=
								  the action level for >= 30 days in any 12 consecutive months, and is not
								  exposed on any day above 10 µg/m3 as an 8-hour
								  TWA; or
is not exposed to lead >=
								  the action level for >= 15 days in any 12 consecutive months, and is not
								  exposed on any day above 20 µg/m3 as an 8-hour
								  TWA.
who perform PSLW and an
								  exposure assessment has not been completed.
C. Schedule of BLL tests required to be made
								  available for employees when their:
Every 2 months for the
								  first 6 months after initial placement, and also for the first 6 months after a
								  change in task resulting in higher exposure, and then every 6 months.
1. Last BLL was < 10 µg/dl, and the
								  employee is included in B above.
Every 2 months. Continue
								  until 2 BLLs, taken at least 30 days apart, are < 10 µg/dl.
2. Last BLL was >= 10 µg/dl but < 20
								  µg/dl.
Every 1 month.
3. Last BLL was >= 20 µg/dl.
D. Medical examinations and consultations
								  required to be made available prior to assignment.
Prior to
								  assignment for employees who will be:
exposed >= action
								  level.
NOTE: medical examination and
								  consultation prior to assignment is not required for an employee who:
is not exposed to lead >=
								  the action level for >= 30 days in any 12 consecutive months, and is not
								  exposed on any day above 10 µg/m3 as an 8-hour
								  TWA; or
is not exposed to lead >=
								  the action level for >= 15 days in any 12 consecutive months, and is not
								  exposed on any day above 20 µg/m3 as an 8-hour
								  TWA.
E. Additional medical examinations and
								  consultations required to be made available.
For employees
								  who are:
exposed >= action level;
								  or
NOTE: medical examination and
								  consultation is not required for an employee who:
is not exposed to lead >=
								  the action level for >= 30 days in any 12 consecutive months, and is not
								  exposed on any day above 10 µg/m3 as an 8-hour
								  TWA; or
is not exposed to lead >=
								  the action level for >= 15 days in any 12 consecutive months, and is not
								  exposed on any day above 20 µg/m3 as an 8-hour
								  TWA.
performing PSLW, and an
								  exposure assessment has not been completed.
F. Schedule of medical examinations and
								  consultations required to be made available, for employees included in E
								  above.
As soon as possible when an employee's BLL is >=
								  20 µg/dl, if no lead-specific medical examination was done in the
								  preceding 12 months; and
annually until the
								  employee's BLL is < 20 µg/dl.
As soon as possible, upon
								  notification by an employee either that the employee has developed signs or
								  symptoms commonly associated with lead intoxication, that the employee desires
								  medical advice concerning the effects of current or past exposure to lead on
								  the employee's ability to procreate a healthy child, that the employee is
								  pregnant, or that the employee has demonstrated difficulty in breathing during
								  a respirator fit test or during use.
Note: Exposure levels in Table 1 are without regard to
						  an employee's use of a respirator.
C. Medical Removal Protection
Results of BLL testing or the recommendations of an
						  examining PLHCP may necessitate removal of an employee from further lead
						  exposure pursuant to the standard's medical removal protection (MRP) program.
						  The objective of the MRP program is to provide temporary medical removal to
						  employees either with substantially elevated BLLs or otherwise at risk of
						  sustaining material health impairment from continued substantial exposure to
						  lead.
Under the standard's employee medical removal criteria,
						  an employee is to be removed from any work having an exposure to lead at or
						  above the action level, altering or disturbing any material containing lead at
						  a concentration equal to or greater than 0.5% by weight, or torch cutting any
						  scrap metal, on each occasion that either:
1. The last blood lead test indicates that the
						  employee's BLL is at or above 30 µg/dl; or
2. Effective January 1, 2026, the last two blood lead
						  test results are at or above 20 µg/dl; or
3. Effective January 1, 2026, the average of the
						  results of all blood lead tests conducted in the last 6 months is at or above
						  20 µg/dl, unless the last blood test indicates a blood lead level below
						  15 µg/dl, in which case the employee need not be removed.
Medical removal is to continue until two consecutive
						  BLLs at least 30 days apart are below 15 µg/dl.
In addition to the above BLL criteria, temporary
						  medical removal for employees may also take place as a result of medical
						  determinations and recommendations. A written medical opinion must be prepared
						  after each examination pursuant to the standard. If the examining PLHCP
						  includes a medical finding, determination or opinion that the employee has a
						  health-related condition which places the employee's health, including the
						  ability to procreate a healthy child, at increased risk of material impairment
						  from exposure to lead, then the employee must be removed from any work having
						  an exposure to lead at or above the action level, altering or disturbing any
						  material containing lead at a concentration equal to or greater than 0.5% by
						  weight or torch cutting any scrap metal. Alternatively, if the examining PLHCP
						  recommends special protective measures for an employee (e.g., use of a powered
						  air-purifying respirator) or recommends limitations on an employee's exposure
						  to lead, then the employer must implement these recommendations.
Monthly BLL tests must be made available during the
						  medical removal period for an employee who is removed from exposure to lead due
						  to an elevated BLL. In addition, a medical examination is to be made available
						  as soon as possible and then as medically appropriate to each employee removed
						  from exposure to lead due to an elevated BLL or due to a risk of sustaining
						  material impairment to health, or otherwise limited or specially protected
						  pursuant to medical recommendations.
Recommendations may be more stringent than the specific
						  provisions of the standard. The examining PLHCP, therefore, is given broad
						  flexibility to tailor special protective procedures to the needs of individual
						  employees. This flexibility extends to the evaluation and management of
						  pregnant employees and employees who are planning to raise children. Based on
						  the history, physical examination, and laboratory studies, the PLHCP might
						  recommend special protective measures or medical removal for an employee who is
						  pregnant or who is planning to conceive a child when, in the PLHCP's judgement,
						  continued exposure to lead at the current job would pose a significant risk.
						  The return of the employee to their former job status, or the removal of
						  special protections or limitations, depends upon the examining PLHCP
						  determining that the employee is no longer at increased risk of material
						  impairment or that special measures are no longer needed.
During the period of any form of special protection or
						  removal, the employer must maintain the employee's earnings, seniority, and
						  other employment rights and benefits (as though the employee had not been
						  removed) for a period of up to 18 months. This economic protection will
						  maximize meaningful employee participation in the medical surveillance program,
						  and is appropriate as part of the employer's overall obligation to provide a
						  safe and healthful workplace. The provisions of MRP benefits during the
						  employee's removal period may, however, be conditioned upon participation in
						  medical surveillance.
On rare occasions, an employee's BLL may not acceptably
						  decline within 18 months of removal. This situation will arise only in unusual
						  circumstances, thus the standard relies on an individual medical examination to
						  determine how to protect such an employee. This medical determination is to be
						  based on both laboratory values, including BLLs, zinc protoporphyrin levels,
						  blood counts, and other tests felt to be warranted, as well as the PLHCP's
						  judgment that any symptoms or findings on physical examination are a result of
						  lead toxicity. The medical determination may be that the employee is incapable
						  of ever safely returning to their former job status. The medical determination
						  may provide additional removal time past 18 months for some employees or
						  specify special protective measures to be implemented.
The requirements of section
						  5198 for the temporary removal of
						  an exposed employee and their subsequent return to work with lead are
						  summarized in Table 2.Table 2. Minimum Requirements During the Medical Removal
						  Protection (MRP) Period.
A. BLL requiring employee medical
								  removal.
one BLL >= 30 µg/dl; or
effective January 1, 2026, the last two
								  BLLs are >= 20 µg/dl; or
effective January 1, 2026, the average
								  of all BLLs over the last 6 months is >= 20 µg/dl, unless the last
								  blood test indicates a blood lead level below 15 µg/dl, in which case the
								  employee need not be removed.
B. MRP due to a final medical
								  determination.
A written medical opinion on the employee's health
								  status by the examining PLHCP results in a medical finding, determination, or
								  opinion that the employee has a detected health-related condition which places
								  the employee's health, including the ability to procreate a healthy child, at
								  increased risk of material impairment from exposure to lead.
C. Frequency of BLL tests required to be made
								  available for an employee removed from exposure to lead because of an elevated
								  BLL.
Every 1 month.
D. Medical examinations and consultations
								  required to be made available.
As soon as possible, then as medically
								  appropriate, for an employee:
removed from exposure to lead due to
								  elevated blood lead levels, or
whose exposure to lead is otherwise
								  limited pursuant to a final medical determination.
E. Permissible working conditions for an employee
								  on MRP.
Employee must be removed from any work:
having an exposure to lead (without
								  regard to respirator use) >= the action level; or
altering or disturbing any material
								  containing lead at a concentration >= 0.5% by weight; or
torch cutting any scrap metal.
F. When an employee has been placed on MRP due to
								  elevated BLL, the BLL at which an employee can return to their former
								  work.
Two consecutive BLLs, taken at least 30 days apart, both indicate
								  a BLL < 15 µg/dl.
G. When an employee has been placed on MRP due to
								  a final medical determination, the conditions under which an employee shall be
								  returned to their former work.
A subsequent final medical determination
								  results in a medical finding, determination, or opinion that the employee no
								  longer has a detected health-related condition that places the employee's
								  health, including the ability to procreate a healthy child, at increased risk
								  of material impairment from exposure to lead.
Note: When a medical opinion indicates that an employee
						  is at risk of material impairment from exposure to lead, the PLHCP can remove
						  an employee from exposures exceeding the action level (or less) or recommend
						  special protective measures as deemed appropriate and necessary. Medical
						  monitoring during the medical removal period can be more stringent than noted
						  in the table above if the PLHCP so specifies. Return to work or removal of
						  limitations and special protection is permitted when the PLHCP indicates that
						  the employee is no longer at risk of material impairment.
The lead standard provides for a multiple PLHCP review
						  in cases where the employee wishes a second opinion concerning potential lead
						  poisoning or toxicity. If an employee wishes a second opinion, they can make an
						  appointment with a PLHCP of their choice. This second PLHCP will review the
						  findings, recommendations or determinations of the first PLHCP and conduct any
						  examinations, consultations or tests deemed necessary in an attempt to make a
						  final medical determination. If the first and second PLHCPs do not agree in
						  their assessment they must try to resolve their differences. If they cannot
						  reach an agreement then they must designate a third PLHCP to resolve the
						  dispute.
D. Requirements for Providing Information to
						  Laboratories, Employees, Employers, and PLHCPs
For Blood Lead Tests:
The employer must instruct the PLHCP who orders blood
						  lead tests to provide the analyzing laboratory with complete employee
						  identification information. This information includes:
1. Employee name, date of birth, address, and phone
						  number; and
2. Employer name, address, and phone number.
The employer must ensure that the ordering PLHCP
						  explains the findings of any blood lead test and notifies the employee of the
						  following:
1. The results of the blood lead test;
2. Any recommended follow-up blood lead testing in
						  accordance with subsection (j)(2)(A) and the timing of that recommended blood
						  lead testing; and
3. If the employee's blood lead level is 20 µg/dl
						  or greater, the recommendation that the employee undergo a medical examination
						  by a PLHCP if the employee has not had a lead-specific medical exam in the
						  preceding 12 months.
In addition, the employer is required to provide a
						  written notification to the employee within five working days after the receipt
						  of the employee's blood lead test results. The employer must notify each
						  employee:
1. Of that employee's BLL;
2. That the standard requires the employer to make
						  medical examinations and consultations available to employees exposed at or
						  above the action level, and as interim protection, to employees performing
						  PSLW, unless an employee's exposure or work is covered by the exception in
						  subsection (j)(1)(A). When they are required, the employer must make medical
						  examinations and consultations available as soon as possible, upon notification
						  by an employee either that the employee has developed signs or symptoms
						  commonly associated with lead intoxication, that the employee desires medical
						  advice concerning the effects of current or past exposure to lead on the
						  employee's ability to procreate a healthy child, or that the employee has
						  demonstrated difficulty breathing during a respirator fit test or during use;
						  and
3. That the standard requires medical removal with MRP
						  benefits when an employee's BLL exceeds any of the limits defined for medical
						  removal.
For Medical Examination and Consultation:
The employer must provide examining and consulting
						  PLHCPs with the following specific information:
1. A copy of the lead standard and all
						  appendices;
2. A description of the employee's duties as related to
						  exposure;
3. The exposure level or anticipated level to lead and
						  any other toxic substances (if applicable);
4. A description of personal protective equipment
						  used;
5. Prior BLLs;
6. All prior written medical opinions regarding the
						  employee in the employer's possession or control; and
7. A copy of the employer's written elevated blood lead
						  level response plan for that employee (required when an employee's BLL is at or
						  above 10 µg/dl).
The employer must ensure that the PLHCP explains to the
						  employee the results of the medical examination and provides each employee with
						  a written medical report within 30 days of each medical examination performed.
						  The written report shall contain:
1. The PLHCP's opinion as to whether the employee has
						  any detected health-related condition that would place the employee's health,
						  including the ability to procreate a healthy child, at increased risk of
						  material impairment from exposure to lead;
2. Any recommended special protective measures to be
						  provided to the employee, or recommended limitations to be placed upon the
						  employee's exposure to lead;
3. Any recommended limitations upon the employee's use
						  of respirators, including a determination of whether the employee should wear a
						  powered air-purifying respirator (PAPR) instead of a non-powered air-purifying
						  respirator;
4. The employee's BLL;
5. Any recommended follow-up blood lead testing and
						  medical examinations and the timing of each; and
6. The PLHCP's opinion as to whether the employee has
						  any health-related condition, occupational or non-occupational, that dictates
						  further medical examination or treatment.
The employer must also obtain a written medical opinion
						  from the examining PLHCP within 30 days of the medical examination. The written
						  opinion shall contain the following information:
1. The PLHCP's opinion as to whether the employee has
						  any detected health-related condition that would place the employee's health,
						  including the ability to procreate a healthy child, at increased risk of
						  material impairment from exposure to lead;
2. Any recommended special protective measures to be
						  provided to the employee, or limitations to be placed upon the employee's
						  exposure to lead;
3. Any recommended limitation upon the employee's use
						  of respirators, including a determination of whether the employee can wear a
						  PAPR if the PLHCP determines that the employee cannot wear a negative pressure
						  respirator; and
4. The employee's BLL.
Employers must instruct each PLHCP not to reveal to the
						  employer in writing or in any other way their findings, laboratory results, or
						  diagnoses which are felt to be unrelated to occupational lead exposure.
E. Additional Requirements
The standard provides for the use of respirators where
						  engineering and other primary controls do not provide adequate protection.
						  However, the use of respiratory protection shall not be used in lieu of
						  temporary medical removal due to elevated BLLs or findings that an employee is
						  at risk of material health impairment. This is based on the numerous
						  inadequacies of respirators including skin rash where the facepiece makes
						  contact with the skin, unacceptable stress to breathing in some employees with
						  underlying cardiopulmonary impairment, difficulty in providing adequate fit,
						  the tendency for respirators to create additional hazards by interfering with
						  vision, hearing, and mobility, and the difficulties of assuring the maximum
						  effectiveness of a complicated work practice program involving respirators.
						  Respirators do, however, serve a useful function where engineering and work
						  practice controls are inadequate by providing supplementary, interim, or
						  short-term protection, provided they are properly selected for the environment
						  in which the employee will be working, properly fitted to the employee,
						  maintained and cleaned periodically, and worn by the employee when required. If
						  the employer selects filtering facepiece respirators for protection against
						  lead, they shall be N100, R100, or P100. Also, a PAPR is much more protective
						  than a typical negative pressure respirator, and may also be more comfortable
						  to wear. The standard provides that an employer must provide a PAPR to an
						  employee upon request.
Prophylactic chelation is prohibited by the lead
						  standard. Diagnostic and therapeutic chelation are permitted only when done by
						  a PLHCP with appropriate medical monitoring in an acceptable clinical setting.
						  The decision to initiate chelation therapy must be made on an individual basis
						  and must take into account the severity of symptoms felt to be a result of lead
						  toxicity along with BLLs, zinc protoporphyrin (ZPP) levels, and other
						  laboratory tests as appropriate. Calcium disodium EDTA
						  (CaNa2EDTA) and succimer, which are the primary
						  chelating agents used in the therapy of occupational lead poisoning, have
						  significant potential side effects and their use must be justified on the basis
						  of expected benefits to the employee. Unless frank and severe symptoms are
						  present, therapeutic chelation is not recommended, given the opportunity to
						  remove an employee from exposure and allow the body to naturally excrete
						  accumulated lead. As a diagnostic aid, the chelation mobilization test has
						  limited applicability. It offers very limited utility as a biomarker of
						  long-term lead exposure, and does not predict the clinical efficacy of
						  chelation.
Employers are required to ensure that accurate records
						  are maintained on exposure monitoring, medical surveillance, and medical
						  removal for each employee. Exposure monitoring and medical surveillance records
						  must be kept for 40 years or the duration of employment plus 20 years,
						  whichever is longer, while medical removal records must be maintained for the
						  duration of employment. All records required under the standard must be
						  available upon request to the Cal/OSHA Chief and the Director of the National
						  Institute for Occupational Safety and Health (NIOSH). Employers must also make
						  environmental and biological monitoring and medical removal records available
						  to affected employees and to former employees or their authorized employee
						  representatives. Employees or their specifically designated representatives
						  have access to their entire medical surveillance records.
In addition, the standard requires that the employer
						  inform all employees who are exposed to lead at or above the action level on
						  any one day; for whom the possibility exists of skin or eye irritation from
						  exposure to lead; or who perform PSLW and an exposure assessment has not been
						  completed, of the provisions of the standard and all its appendices, the
						  purpose and description of medical surveillance, and provisions for medical
						  removal protection if temporary removal is required. An understanding of the
						  potential health effects of lead exposure by all exposed employees along with
						  full understanding of their rights under the lead standard is essential for an
						  effective monitoring program.
II. Adverse health effects of inorganic lead.
Although the toxicity of lead has been known for 2,000
						  years, the knowledge of the complex relationship between lead exposure and
						  human response is still being refined. Significant research into the toxic
						  properties of lead continues throughout the world. Scientific evidence shows
						  multiple health effects at BLLs once thought to be without recognized harm.
						  Prolonged exposure to lead levels below the previous Cal/OSHA BLL threshold of
						  50 µg/dl can result in adverse cumulative effects. Some of these health
						  effects may be reversible and some may be permanent.
The provisions of the lead standard are founded on two
						  prime medical judgments: first, the prevention of adverse health effects from
						  exposure to lead throughout a working lifetime requires that employee BLLs be
						  maintained as low as possible; and second, the BLLs of employees who are trying
						  to conceive should be maintained below 3.5 µg/dl to minimize adverse
						  reproductive health effects. The lead standard is designed to detect BLL
						  increases early and take action to control exposures. The adverse effects of
						  lead on reproduction are being actively researched and the PLHCP is encouraged
						  to remain abreast of recent developments in the area to best advise pregnant
						  employees or employees planning to conceive children.
The spectrum of health effects caused by lead exposure
						  can be subdivided into four developmental stages: physiological changes of
						  uncertain significance, pathophysiological changes, overt symptoms (morbidity),
						  and mortality. Within this process there are no sharp distinctions, but rather
						  a continuum of effects. Boundaries between categories overlap due to the wide
						  variation of individual responses and exposures in the working population. The
						  development of the lead standard focused on pathophysiological changes as well
						  as later stages of disease.
In terms of mechanisms of disease, lead interferes with
						  cellular metabolism in tissues throughout the body. As a divalent cation, lead
						  interferes with calcium metabolism which affects, for example,
						  neurotransmission and vascular tone. Lead has a high affinity for negatively
						  charged sulfhydryl groups, ultimately affecting synthesis of heme required for
						  production of hemoglobin; cytochromes involved in cellular respiration; and
						  microsomal oxidases involved in biotransformation pathways. In addition, lead
						  increases reactive oxygen species, which affects vascular tone. Lead also
						  affects cell membranes and nucleic acids with multi-system effects. In the
						  nervous system, lead alters the permeability of the blood brain barrier and
						  accumulates in astroglia. Other modes of action include cell death,
						  genotoxicity, inflammation, and endocrine disruption.
1. Cardiovascular Effects. Current evidence indicates a
						  causal relationship between lead exposure and hypertension, and between lead
						  exposure and coronary heart disease. Prospective cohort studies have
						  demonstrated an approximate 50% increase in cardiovascular mortality associated
						  with chronic BLLs of 10 µg/dl or greater. Increased cardiovascular
						  mortality has also been associated with BLLs below 10 µg/dl. Various
						  mechanisms of action may mediate the hypertensive effect, including oxidative
						  stress, inflammation, hormonal and blood pressure regulatory system
						  dysfunction, and vasomodulator imbalance. These mechanisms, and possibly
						  subclinical atherosclerosis which has been demonstrated in some studies,
						  likewise contribute to coronary heart disease. Since hypertension is a
						  significant risk factor for heart disease, stroke, and renal insufficiency,
						  lead exposure may exert an important influence on cardiovascular,
						  cerebrovascular, and renovascular mortality. Nonetheless, lead exposure is
						  associated with increased cardiovascular and stroke mortality even after
						  accounting for the effects of hypertension.
2. Heme Synthesis Inhibition. The earliest hematologic
						  effect involves lead's ability to inhibit at least two enzymes of the heme
						  synthesis pathway at very low BLLs. Inhibition of delta aminolevulinic acid
						  dehydratase (ALA-D) which catalyzes the conversion of delta-aminolevulinic acid
						  (ALA) to protoporphyrin is observed at a BLL as low as 10 µg/dl. At a BLL
						  of 40 µg/dl, more than 20% of the population would have 70% inhibition of
						  ALA-D. There is an exponential increase in ALA excretion at BLLs greater than
						  40 µg/dl.
Another enzyme, ferrochelatase, is also inhibited at
						  low BLLs. Inhibition of ferrochelatase leads to increase free erythrocyte
						  protoporphyrin (FEP) in the blood which can then bind to zinc to yield zinc
						  protoporphyrin (ZPP). At a BLL of 50 µg/dl or greater, nearly 100% of the
						  population will have an increase in FEP. There is also an exponential
						  relationship between BLLs greater than 40 µg/dl and the associated ZPP
						  level, which has led to the development of the ZPP screening test for lead
						  exposure.
While the significance of these effects is subject to
						  debate, these enzymatic disturbances are early stages of a disease process
						  which eventually results in the clinical symptoms of lead poisoning. Whether or
						  not the effects do progress to the later stages of clinical disease, disruption
						  of these enzymatic processes over a working lifetime is a material impairment
						  of health.
One of the eventual results of lead-induced inhibition
						  of enzymes in the heme synthesis pathway is anemia which can be asymptomatic if
						  mild, but is associated with a wide array of symptoms including dizziness,
						  fatigue, and tachycardia when more severe. Hematopoietic effects tend to occur
						  at a BLL threshold of 10-20 µg/dl; however, bone lead stores from chronic
						  exposure may continue to exert subclinical effects on hematopoiesis, regardless
						  of current BLL.Once BLLs reach 50 µg/dl, a definite decrease in
						  hemoglobin is evident, although most cases of lead-induced anemia, as well as
						  shortened red-cell survival times, occur at BLLs exceeding 80 µg/dl.
						  Inhibited hemoglobin synthesis is more common in chronic cases, whereas
						  shortened erythrocyte life span is more common in acute cases.
In lead-induced anemias, there is usually a
						  reticulocytosis along with the presence of basophilic stippling, and ringed
						  sideroblasts, although none of the above are pathognomonic for lead-induced
						  anemia.
3. Neurological Effects. Inorganic lead has been found
						  to have toxic effects on both the central and peripheral nervous systems. The
						  earliest stages of lead-induced central nervous system effects are manifested
						  by behavioral disturbances and central nervous system symptoms including
						  irritability, restlessness, insomnia and other sleep disturbances, fatigue,
						  vertigo, headache, poor memory, tremor, depression, and apathy. With more
						  severe exposure, symptoms can progress to drowsiness, stupor, hallucinations,
						  delirium, convulsions, and coma.
The most severe and acute form of lead poisoning which
						  usually follows ingestion or inhalation of large amounts of lead is acute
						  encephalopathy which may arise precipitously with the onset of intractable
						  seizures, coma, cardiopulmonary arrest, and death within 48 hours.
Lead exposure is associated with decrements in
						  neurological function in adults. Effects at BLLs [LESS THAN EQUAL TO]10
						  µg/dl include decreased cognitive function, altered behavior and mood,
						  and altered neuromotor and neurosensory function. At higher BLLs, a variety of
						  decrements in cognitive function and behavior and nerve function can occur.
						  These effects may be irreversible.
The peripheral neuropathy resulting from lead exposure
						  characteristically involves only motor function with minimal sensory damage and
						  has a marked predilection for the extensor muscles of the most active
						  extremity. The peripheral neuropathy can occur with varying degrees of
						  severity. The earliest and mildest form which can be detected in employees with
						  BLLs over 30 µg/dl is manifested by slowing of motor nerve conduction
						  velocity often without clinical symptoms. With progression of the neuropathy
						  there is development of painless extensor muscle weakness usually involving the
						  extensor muscles of the fingers and hand in the most active upper extremity,
						  followed in severe cases by wrist drop or, much less commonly, foot
						  drop.
In addition to slowing of nerve conduction,
						  electromyographical studies in patients with BLLs greater than 50 µg/dl
						  have demonstrated a decrease in the number of acting motor unit potentials, an
						  increase in the duration of motor unit potentials, and spontaneous pathological
						  activity including fibrillations and fasciculations. Essential tremor in some
						  studies has been shown to occur at BLLs less than 10 µg/dl.
While the peripheral neuropathies can occasionally be
						  reversed with therapy, again such recovery is not assured particularly in the
						  more severe neuropathies and often improvement is only partial. The lack of
						  reversibility is felt to be due in part to segmental demyelination.
4. Lead colic may develop at 80 µg/dl, whereas
						  milder, nonspecific gastrointestinal discomfort and constipation occur with
						  levels higher than 60 µg/dl.
5. Renal. Renal toxicity represents one of the most
						  serious health effects of lead poisoning. Kidney dysfunction is thought to
						  occur at chronic BLLs of 5-10 µg/dl or greater but also may arise after
						  acute high-dose lead exposures. In the early stages of disease nuclear
						  inclusion bodies can frequently be identified in proximal renal tubular cells.
						  Renal function remains normal and the changes in this stage are probably
						  reversible. With more advanced disease there is progressive interstitial
						  fibrosis and impaired renal function. Eventually extensive interstitial
						  fibrosis ensues with sclerotic glomeruli and dilated and atrophied proximal
						  tubules; all represent end stage kidney disease. Azotemia can be progressive,
						  eventually resulting in frank uremia necessitating dialysis. There is
						  occasionally associated hypertension and hyperuricemia with or without
						  gout.
Early kidney disease is difficult to detect. The
						  urinalysis is normal in early lead nephropathy and the blood urea nitrogen and
						  serum creatinine increase only when two-thirds of kidney function is lost.
						  Measurement of creatinine clearance can often detect earlier disease as can
						  other methods of measurement of glomerular filtration rate. An abnormal
						  chelation mobilization test has been used to differentiate between lead-induced
						  and other nephropathies, but this procedure is not widely accepted.
6. Reproductive Effects. Exposure to lead can have
						  serious effects on reproductive function in both males and females. In male
						  employees exposed to lead there can be a decrease in sexual drive, impotence,
						  decreased ability to produce healthy sperm, and sterility. Malformed sperm
						  (teratospermia), decreased number of sperm (hypospermia), and sperm with
						  decreased motility (asthenospermia) can all occur. These adverse effects may
						  occur at BLLs of 20 µg/dl or greater. Furthermore, there appears to be a
						  dose-response relationship for teratospermia in lead- exposed employees.
Females exposed to lead may experience menstrual
						  disturbances including dysmenorrhea, menorrhagia, and amenorrhea. Following
						  exposure to lead, females have a higher frequency of sterility, premature
						  births, spontaneous miscarriages, and stillbirths.
Germ cells can be affected by lead and lead can cause
						  genetic damage in the egg or sperm cells before conception and contribute to
						  failure to implant, miscarriage, stillbirth, or birth defects.
Maternal lead exposure during pregnancy is associated
						  with gestational hypertension, spontaneous abortion, low birth weight, and
						  impaired neurodevelopment.
Lead can pass through the placental barrier and lead
						  levels in the birthing parent's blood are comparable to concentrations of lead
						  in the umbilical cord at birth. Transplacental passage becomes detectable at
						  12-14 weeks of gestation and increases until birth.
There is little direct data on damage to the fetus from
						  exposure to lead but it is generally assumed that the fetus and newborn would
						  be at least as susceptible to neurological damage as young children. Current
						  evidence indicates that there is no known lower limit of toxicity at any age.
						  Lead exposure in children can cause significant neurobehavioral impairments
						  including cognitive dysfunction and hyperactivity. Therefore, people planning
						  to conceive should maintain BLLs less than 3.5 µg/dl.
7. Other Toxic Effects. Debate and research continue on
						  the effects of lead on the human body. Lead may impair the immune and endocrine
						  systems, including thyroid function and the pituitary-adrenal axis, but these
						  effects and the corresponding level of exposure have not been well defined.
						  Also, although the epidemiologic data is limited and inconsistent, based on
						  toxicologic data and animal studies, lead is considered a probable human
						  carcinogen by several authoritative sources.
III. Medical Evaluation
The most important principle in evaluating an employee
						  for any occupational disease, including lead poisoning, is a high index of
						  suspicion on the part of the examining PLHCP. As discussed in section II, lead
						  can affect numerous organ systems and produce a wide array of signs and
						  symptoms, most of which are non-specific and subtle in nature at least in the
						  early stages of disease. Unless serious concern for lead toxicity is present,
						  many of the early clues to diagnosis may easily be overlooked.
The crucial initial step in the medical evaluation is
						  recognizing that an employee's employment can result in exposure to lead. The
						  employee will frequently be able to define exposures to lead and
						  lead-containing materials but often will not volunteer this information unless
						  specifically asked. In other situations the employee may not know of any
						  exposures to lead but the suspicion might be raised on the part of the PLHCP
						  because of the industry or occupation of the employee. Potential occupational
						  exposure to lead and its compounds occur in at least 120 occupations, including
						  lead smelting, the manufacture of lead storage batteries, the manufacture of
						  lead pigments and products containing pigments, solder manufacture,
						  shipbuilding and ship repair, auto manufacturing and repair, scrap yard work,
						  construction, painting, and work with firearms and ammunition.
Once the possibility for lead exposure is known, the
						  focus can then be directed toward eliciting information from the medical
						  history, physical examination, and finally from laboratory data to evaluate the
						  employee for potential lead toxicity.
A complete and detailed work history is important in
						  the initial evaluation. A listing of all previous employment with information
						  on work processes, exposure to fumes or dust, known exposures to lead or other
						  toxic substances, respiratory protection used, and previous medical
						  surveillance should all be included in the employee's record. Where exposure to
						  lead is suspected, information concerning on-the-job personal hygiene, smoking
						  or eating habits in work areas, laundry procedures, and use of any protective
						  clothing or respiratory protection equipment should be noted. A complete work
						  history is essential in the medical evaluation of an employee with suspected
						  lead toxicity, especially when long term effects such as neurotoxicity and
						  nephrotoxicity are considered.
The medical history is also of fundamental importance
						  and should include a listing of all past and current health-related conditions,
						  current medications including proprietary drug intake and ethnic remedies,
						  previous surgeries and hospitalizations, allergies, smoking history, alcohol
						  consumption, and also non-occupational lead exposures such as hobbies (hunting,
						  riflery). Also, known childhood exposures should be elicited. Any previous
						  history of cardiovascular, hematological, neurological, gastrointestinal,
						  renal, psychological, gynecological, genetic, or reproductive problems should
						  be specifically noted.
A careful and complete review of systems must be
						  performed to assess both recognized complaints and subtle or slowly acquired
						  symptoms which the employee might not appreciate as being significant. The
						  review of symptoms should include the following:
1. General weight loss, fatigue, decreased
						  appetite.
2. Head, Eyes, Ears, Nose, Throat (HEENT) -- headaches,
						  visual disturbances or decreased visual acuity, hearing deficits or tinnitus,
						  pigmentation of the oral mucosa, or metallic taste in mouth.
3. Cardiopulmonary -- shortness of breath, cough, chest
						  pains, palpitations, or orthopnea.
4. Gastrointestinal -- nausea, vomiting, heartburn,
						  abdominal pain, constipation or diarrhea.
5. Neurologic -- irritability, insomnia, weakness
						  (fatigue), dizziness, loss of memory, confusion, hallucinations,
						  incoordination, ataxia, decreased strength in hands or feet, disturbances in
						  gait, difficulty in climbing stairs, or seizures.
6. Hematologic -- pallor, easily fatigued, abnormal
						  blood loss, melena.
7. Reproductive -- (male and female and spouse where
						  relevant) history of infertility, impotence, loss of libido, abnormal menstrual
						  periods, history of miscarriages, stillbirths, or children with birth
						  defects.
8. Musculo-skeletal -- muscle and joint pains.
The physical examination should emphasize the
						  neurological, gastrointestinal, and cardiovascular systems. The employee's
						  weight and blood pressure should be recorded. Historically, the oral mucosa was
						  checked for pigmentation characteristic of a possible Burtonian or lead line on
						  the gingiva. However, the lead line may not be present even in severe lead
						  poisoning if good oral hygiene is practiced.
The presence of pallor on skin examination may indicate
						  an anemia, which if severe might also be associated with a tachycardia. If an
						  anemia is suspected, an active search for blood loss should be undertaken
						  including potential blood loss through the gastrointestinal tract.
A complete neurological examination should include an
						  adequate mental status evaluation including a search for behavioral and
						  psychological disturbances, memory testing, evaluation for irritability,
						  insomnia, hallucinations, and mental clouding. Gait and coordination should be
						  examined along with close observation for tremor. A detailed evaluation of
						  peripheral nerve function including careful sensory and motor function testing
						  is warranted. Strength testing particularly of extensor muscle groups of all
						  extremities is of fundamental importance.
Cranial nerve evaluation should also be included in the
						  routine examination.
The abdominal examination should include auscultation
						  for bowel sounds and abdominal bruits and palpation for organomegaly, masses,
						  and diffuse abdominal tenderness.
Cardiovascular examination should evaluate possible
						  early signs of ischemic heart disease and congestive heart failure. Pulmonary
						  status should be addressed particularly if respiratory protection is
						  contemplated.
As part of the medical evaluation, the lead standard
						  requires the following laboratory studies:
1. Blood lead level.
2. Hemoglobin and hematocrit determinations, red cell
						  indices, and examination of the peripheral blood smear to evaluate red blood
						  cell morphology.
3. Blood urea nitrogen.
4. Serum creatinine.
5. Routine urinalysis with microscopic
						  examination.
6. A zinc protoporphyrin (ZPP) level for each employee
						  whose last blood lead level was at or above 20 µg/dl.
In addition to the above, the PLHCP is authorized to
						  order any further laboratory or other tests which they deem necessary in
						  accordance with sound medical practice. The evaluation must also include
						  pregnancy testing or laboratory evaluation of male fertility if requested by
						  the employee.
Additional tests which are probably not warranted on a
						  routine basis but may be appropriate when blood lead and ZPP levels are
						  equivocal include delta-aminolevulinic acid and coproporphyrin concentrations
						  in the urine, and dark-field illumination for detection of basophilic stippling
						  in red blood cells.
If an anemia is detected further studies including a
						  careful examination of the peripheral smear, reticulocyte count, stool for
						  occult blood, serum iron, total iron binding capacity, bilirubin, and, if
						  appropriate, vitamin B12 and folate may be of value in attempting to identify
						  the cause of the anemia.
If a peripheral neuropathy is suspected, nerve
						  conduction studies are warranted both for diagnosis and as a basis to monitor
						  any therapy.
If renal disease is questioned, a 24-hour urine
						  collection for creatinine clearance, protein, and electrolytes may be
						  indicated. Elevated uric acid levels may result from lead-induced renal disease
						  and a serum uric acid level might be performed.
An electrocardiogram and chest X-ray may be obtained as
						  deemed appropriate.
Sophisticated and highly specialized testing should not
						  be done routinely and where indicated should be under the direction of a
						  specialist.
IV. Laboratory Evaluation
The BLL at present remains the single most important
						  test to monitor lead exposure and is the test used in the medical surveillance
						  program under the lead standard to guide employee medical removal. The ZPP
						  currently remains an ancillary test due to its lack of sensitivity.
This section will discuss the BLL and ZPP in detail and
						  will outline their relative advantages and disadvantages. Other blood tests
						  currently available to evaluate lead exposure will also be reviewed.
BLL, a measure of the amount of lead currently found in
						  the blood, reflects both recent exogenous exposure as well as endogenous
						  redistribution of lead stored in bone. BLL does not reflect the body burden.
						  One reason for this is that lead has a high affinity for bone and up to 90% of
						  the body's total lead is deposited there. A very important component of the
						  total lead body burden is lead in soft tissue (liver, kidney, and brain). This
						  fraction of the lead body burden, the biologically active lead, is not entirely
						  reflected by BLLs since it is a function of the dynamics of lead absorption,
						  distribution, deposition in bone and excretion. Following discontinuation of
						  exposure to lead, the excess body burden is only slowly mobilized from bone and
						  other relatively stable body stores and excreted.
When interpreting a person's BLL, three key questions
						  to keep in mind are whether the exposure history has been acute or chronic;
						  recent or remote; high or low. For instance, a high BLL may only represent
						  recent heavy exposure to lead without a significant total body excess and
						  likewise a low BLL does not exclude an elevated total body burden of
						  lead.
Also, due to its correlation with recent exposures, the
						  BLL may vary considerably over short time intervals.
To minimize laboratory error and erroneous results due
						  to contamination, blood specimens must be carefully collected (after thorough
						  cleaning of the skin with appropriate methods) using lead-free blood containers
						  and analyzed by a reliable laboratory. Under the standard, samples must be
						  analyzed in laboratories that are CLIA-approved (under the federal Clinical
						  Laboratory Improvement Amendments (CLIA) regulations).
The determination of lead in urine is generally
						  considered a less reliable monitoring technique than analysis of whole blood
						  primarily due to individual variability in urinary excretion capacity as well
						  as the technical difficulty of obtaining accurate 24-hour urine collections. In
						  addition, employees with renal insufficiency, whether due to lead or some other
						  cause, may have decreased lead clearances and consequently urine lead levels
						  may underestimate the true lead burden. Therefore, urine lead levels should not
						  be used as a routine test.
The ZPP test, unlike the blood lead determination, is
						  an indirect and relatively insensitive biomarker of lead absorption. Zinc
						  protoporphyrin results from the inhibition of the enzyme ferrochelatase which
						  catalyzes the insertion of an iron molecule into the protoporphyrin molecule,
						  which then becomes heme. If iron is not inserted into the molecule, then zinc,
						  having a greater affinity for protoporphyrin, takes the place of the iron,
						  forming ZPP.
The level of circulating ZPP may not rise until a BLL
						  of 20 µg/dl in some adults and is not greater than 90% sensitive until
						  the BLL exceeds 50 µg/dl. Increases in BLLs beyond 40 µg/dl are
						  associated with exponential increases in ZPP. The upper limit of normal for ZPP
						  varies some between labs but is usually between 35 and 40 µg/dl.
Whereas BLLs fluctuate over short time spans, ZPP
						  levels remain relatively stable. ZPP is measured directly in red blood cells
						  and is present for the cell's entire 120-day life span. Therefore, the ZPP
						  level in blood reflects the average ZPP production over the previous 3-4 months
						  and consequently the average lead exposure during that time interval. The ZPP
						  requires more time than the blood lead to reach significantly elevated levels;
						  the return to normal after discontinuing lead exposure is also slower, lagging
						  the BLL by about 2-6 weeks. Therefore, the ZPP may be useful to assess
						  chronicity of exposure. For example, an elevated BLL and normal ZPP suggest
						  recent exposure, while an elevated BLL and elevated ZPP suggest chronic/ongoing
						  exposure.
It is recommended that a hematocrit be determined
						  whenever a confirmed ZPP of 50 µg/dl is obtained to rule out a
						  significant underlying iron deficiency anemia. If the ZPP is in excess of 100
						  µg/dl and not associated with abnormal elevations in BLLs, the laboratory
						  should be checked to be sure that blood leads were determined using a
						  laboratory that is CLIA-approved. Repeat periodic blood lead studies should be
						  obtained in all individuals with elevated ZPP levels to be certain that an
						  associated elevated BLL has not been missed due to transient fluctuations in
						  blood leads.
ZPP has a characteristic fluorescence spectrum with a
						  peak at 594 nanometers which is detectable with a hematofluorometer. The
						  hematofluorometer is accurate and portable and can provide on-site,
						  instantaneous results for employees who can be frequently tested via a finger
						  prick.
However, careful attention must be given to calibration
						  and quality control procedures. Limited data on blood lead-ZPP correlations and
						  the ZPP levels which are associated with the adverse health effects discussed
						  in section II are the major limitations of the test. Also it is difficult to
						  correlate ZPP levels with environmental exposure and there is some variation of
						  response with age and sex.
Levels of delta-aminolevulinic acid (ALA) in the urine
						  are also used as a measure of lead exposure. Increasing concentrations of ALA
						  are believed to result from the inhibition of the enzyme delta-aminolevulinic
						  acid dehydratase (ALA-D). Although the test is relatively easy to perform,
						  inexpensive, and rapid, the disadvantages include variability in results, the
						  necessity to collect a complete 24-hour urine sample which has a specific
						  gravity greater than 1.010, and also the fact that ALA decomposes in the
						  presence of light.
The pattern of porphyrin excretion in the urine can
						  also be helpful in identifying lead intoxication. With lead poisoning, the
						  urine concentrations of coproporphyrins I and II, porphobilinogen and
						  uroporphyrin I rise. The most important increase, however, is that of
						  coproporphyrin III, but its correlations with BLLs and ZPP are not as good as
						  those of ALA. Increases in urinary porphyrins are not diagnostic of lead
						  toxicity and may be seen in porphyria, some liver diseases, and in patients
						  with high reticulocyte counts.
V. Summary. The standard for inorganic lead places
						  significant emphasis on the medical surveillance of all employees exposed to
						  levels of inorganic lead at or above the action level of 2
						  µg/m3 TWA for 10 or more days per year, and as
						  interim protection for those who perform PSLW as defined in the standard. The
						  PLHCP has a fundamental role in this surveillance program, and in the operation
						  of the medical removal protection program.
Even with adequate employee education on the adverse
						  health effects of lead and appropriate training in work practices, personal
						  hygiene and other control measures, the PLHCP has a primary responsibility for
						  evaluating potential lead toxicity in the employee. It is only through a
						  careful and detailed medical and work history, a complete physical examination,
						  and appropriate laboratory testing that an accurate assessment can be made.
						  Many of the adverse health effects of lead toxicity are either irreversible or
						  only partially reversible and therefore early detection of disease is very
						  important.
This document outlines the medical monitoring program
						  as defined by the occupational safety and health standard for inorganic lead.
						  It reviews the adverse health effects of lead poisoning and describes the
						  important elements of the history and physical examinations as they relate to
						  these adverse effects. Finally, the appropriate laboratory testing for
						  evaluating lead exposure and toxicity is presented.
It is hoped that this review and discussion will give
						  PLHCPs a better understanding of the Cal/OSHA lead standard, with the ultimate
						  goal of protecting the health and well-being of employees exposed to lead who
						  are under their care.