California Code of Regulations › Title 8 - Industrial Relations › Division 1 - Department of Industrial Relations › Chapter 4 - Division of Industrial Safety › Subchapter 4 - Construction Safety Orders › Article 4 - Dusts, Fumes, Mists, Vapors, and Gases › Appendix C to Section 1532.1 - Medical Surveillance Guidelines

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
Introduction
The primary purpose of the Occupational Safety and Health
						Act of 1970 is to assure, so far as possible, safe and healthful working
						conditions for every working man and woman. The occupational health standard
						for lead in construction is designed to protect workers 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 50 [MICRO]g/m3 (micrograms
						per cubic meter) based on 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 50 [MICRO]g/m3 exposure
						limit.
The standard also provides for a program of biological
						monitoring for employees exposed to lead above the action level at any time,
						and additional medical surveillance for all employees exposed to levels of
						inorganic lead above 30 [MICRO]g/m3 (TWA) for more
						than 30 days per year and whose BLL exceeds 40 [MICRO]g/dl.
The purpose of this document is to outline the medical
						surveillance provisions of the interim standard for inorganic lead in
						construction, and to provide further information to the physician regarding the
						examination and evaluation of workers exposed to inorganic lead.
Section
						1 provides a detailed description
						of the monitoring procedure including the required frequency of blood testing
						for exposed workers, provisions for medical removal protection (MRP), the
						recommended right of the employee to a second medical opinion, and notification
						and recordkeeping requirements of the employer. A discussion of the
						requirements for respirator use and respirator monitoring and OSHA's position
						on prophylactic chelation therapy are also included in this section.
Section
						2 discusses the toxic effects and
						clinical manifestations of lead poisoning and effects of lead intoxication on
						enzymatic pathways in heme synthesis. The adverse effects on both male and
						female reproductive capacity and on the fetus are also discussed.
Section
						3 outlines the recommended medical
						evaluation of the worker 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
						2.
Section
						4 provides detailed information
						concerning the laboratory tests available for the monitoring of exposed
						workers. Included also is a discussion of the relative value of each test and
						the limitations and precautions which are necessary in the interpretation of
						the laboratory results.
I. Medical Surveillance and Monitoring Requirements for
						Workers Exposed to Inorganic Lead
Under the standard for inorganic lead in the construction
						industry, initial medical surveillance consisting of biological monitoring to
						include blood lead and ZPP level determination shall be provided to employees
						exposed to lead at or above the action level on any one day. In addition, a
						program of biological monitoring is to be made available to all employees
						exposed above the action level at any time and additional medical surveillance
						is to be made available to all employees exposed to lead above 30
						[MICRO]g/m3 TWA for more than 30 days each year and
						whose BLL exceeds 40 [MICRO]g/dl. This program consists of periodic blood
						sampling and medical evaluation to be performed on a schedule which is defined
						by previous laboratory results, worker complaints or concerns, and the clinical
						assessment of the examining physician.
Under this program, the blood lead level (BLL) of all
						employees who are exposed to lead above 30
						[MICRO]g/m3 for more than 30 days per year or whose
						blood lead is above 40 [MICRO]g/dl but exposed for no more than 30 days per
						year is to be determined at least every two months for the first six months of
						exposure and every six months thereafter. The frequency is increased to every
						two months for employees whose last blood lead level was 40 [MICRO]g/dl or
						above. For employees who are removed from exposure to lead due to an elevated
						blood lead, a new blood lead level must be measured monthly. A zinc
						protoporphyrin (ZPP) measurement is strongly recommended on each occasion that
						a blood lead level measurement is made.
An annual medical examination and consultation performed
						under the guidelines discussed in Section
						3 is to be made available to each
						employee exposed above 30 [MICRO]g/m3 for more than
						30 days per year for whom a blood test conducted at any time during the
						preceding 12 months indicated a blood lead level at or above 40 [MICRO]g/dl.
						Also, an examination is to be given to all employees prior to their assignment
						to an area in which airborne lead concentrations each or exceed the 30
						[MICRO]g/m3 for more than 30 days per year. In addition, a medical examination
						must be provided as soon as possible after notification by an employee that the
						employee has developed signs and 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 fitting test or during
						respirator use. An examination is also to be made available to each employee
						removed from exposure to lead due to a risk of sustaining material impairment
						to health, or otherwise limited or specially protected pursuant to medical
						recommendations.
Results of biological monitoring or the recommendations
						of an examining physician may necessitate removal of an employee from further
						lead exposure pursuant to the standard's medical removal protection (MRP)
						program. The object of the MRP program is to provide temporary medical removal
						to workers either with substantially elevated blood lead levels or otherwise at
						risk of sustaining material health impairment from continued substantial
						exposure to lead.
Under the standard's ultimate worker removal criteria, a
						worker is to be removed from any work having an eight hour TWA exposure to lead
						of 30 [MICRO]g/m3 when his or her blood lead level
						reaches 50 [MICRO]g/dl and is confirmed by a second follow-up blood lead level
						performed within two weeks after the employer receives the results of the first
						blood sampling test. Return of the employee to his or her job status depends on
						a worker's blood lead level declining to 40 [MICRO]g/dl.
As part of the interim standard, the employer is required
						to notify in writing each employee whose blood lead level exceeds 40
						[MICRO]g/dl. In addition each such employee is to be informed that the standard
						requires medical removal with MRP benefits, discussed below, when an employee's
						blood lead level exceeds the above defined limit.
In addition to the above blood lead level criterion,
						temporary worker removal may also take place as a result of medical
						terminations and recommendations. Written medical opinions must be prepared
						after each examination pursuant to the standard. If the examining physician
						includes a medical finding, determination or opinion that the employee has a
						medical condition which places the employee at increased risk of material
						health impairment from exposure to lead, then the employee must be removed from
						exposure to lead at or above 30 [MICRO]g/m3.
						Alternatively, if the examining physician 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.
Recommendations may be more stringent than the specific
						provisions of the standard. The examining physician, 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 workers and male and female workers who are planning to raise
						children. Based on the history, physical examination, and laboratory studies,
						the physician 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 physician's judgment, continued exposure to lead at the current job would
						pose a significant risk. The return of the employee to his or her former job
						status, or the removal of special protections or limitations, depends upon the
						examining physician 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 worker's earnings, seniority, and other
						employment rights and benefits (as though the worker had not been removed) for
						a period of up to 18 months or for as long as the job the employee was removed
						from lasts if less than 18 months. This economic protection will maximize
						meaningful worker 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.
The lead standard provides for a multiple physician
						review in cases where the employee wishes a second opinion concerning potential
						lead poisoning or toxicity. If an employee wishes a second opinion, he or she
						can make an appointment with a physician of his or her choice. This second
						physician will review the findings, recommendations or determinations of the
						first physician and conduct any examinations, consultations or tests deemed
						necessary in an attempt to make a final medical determination. If the first and
						second physicians 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 physician to resolve the dispute.
The employer must provide examining and consulting
						physicians with the following specific information: A copy of the lead
						regulations and all appendices, a description of the employee's duties as
						related to exposure, the exposure level or anticipated level to lead and any
						other toxic substances (if applicable), a description of personal protective
						equipment used, blood lead levels, and all prior written medical opinions
						regarding the employee in the employer's possession or control. The employer
						must also obtain from the physician and provide the employee with a written
						medical opinion containing blood lead levels, the physician's opinion as to
						whether the employee is at risk of material impairment to health, any
						recommended protective measures for the employee if further exposure is
						permitted, as well as any recommended limitations upon an employee's use of
						respirators.
Employers must instruct each physician not to reveal to
						the employer in writing or in any other way his or her findings, laboratory
						results, or diagnoses which are felt to be unrelated to occupational lead
						exposure. They must also instruct each physician to advise the employee of any
						occupationally or non-occupationally related medical condition requiring
						further treatment or evaluation.
The standard provides for the use of respirators where
						engineering and other primary controls are not effective. However, the use of
						respirator protection shall not be used in lieu of temporary medical removal
						due to elevated blood lead levels 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 workers 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.
In its standard on occupational exposure to inorganic
						lead in the construction industry, OSHA has prohibited prophylactic chelation.
						Diagnostic and therapeutic chelation are permitted only under the supervision
						of a licensed physician with appropriate medical monitoring in an acceptable
						clinical setting. The decision to initiate chelation therapy must be made on an
						individual basis and take into account the severity of symptoms felt to be a
						result of lead toxicity along with blood lead levels, ZPP levels, and other
						laboratory tests as appropriate. EDTA and penicillamine 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 worker. Unless frank and severe symptoms are
						prevent, therapeutic chelation is not recommended, given the opportunity to
						remove a worker from exposure and allow the body to naturally excrete
						accumulated lead. As a diagnostic aid, the chelation mobilization test using
						CA-EDTA has limited applicability. According to some investigators, the test
						can differentiate between lead-induced and other nephropathies. The test may
						also provide an estimation of the mobile fraction of the total body lead
						burden.
Employers are required to assure that accurate records
						are maintained on exposure assessment, including environmental monitoring,
						medical surveillance, and medical removal for each employee. Exposure
						assessment records must be kept for at least 30 years. Medical surveillance
						records must be kept for the duration of employment plus 30 years except in
						cases where the employment was less than one year. If duration of employment is
						less than one year, the employer need not retain this record beyond the term of
						employment if the record is provided to the employee upon termination of
						employment. Medical removal records also must be maintained for the duration of
						employment. All records required under the standard must be made available upon
						request to the Chief and the National Institute for Occupational Safety and
						Health. 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 workers exposed to lead at or above 30
						[MICRO]g/m3 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, and it should be anticipated
						that our understanding of thresholds of effects and margins of safety will be
						improved in future years. 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 worker blood
						lead levels be maintained at or below 40 [MICRO]g/dl and second, the blood lead
						levels of workers, male or female, who intend to parent in the near future
						should be maintained below 30 [MICRO]g/dl to minimize adverse reproductive
						health effects to the parents and developing fetus. The adverse effects of lead
						on reproduction are being actively researched and Cal/OSHA encourages the
						physician to remain abreast of recent developments in the area to best advise
						pregnant workers or workers planning to conceive children.
The spectrum of health effects caused by lead exposure
						can be subdivided into five developmental stages: Normal, 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. OSHA's development of the lead standard focused on
						pathophysiological changes as well as later stages of disease.
1. Heme Synthesis Inhibition. The earliest demonstrated
						effect of lead involves its ability to inhibit at least two enzymes of the heme
						synthesis pathway at very low blood levels. Inhibition of delta aminolevulinic
						acid dehydrase (ALA-D) which catalyzes the conversion of delta-aminolevulinic
						acid (ALA) to protoporphyrin is observed at a blood lead level below 20
						[MICRO]g/dl. At a blood lead level of 40 [MICRO]g/dl, more than 20% of the
						population would have 70% inhibition of ALA-D. There is an exponential increase
						in ALA excretion at blood lead levels greater than 40 [MICRO]g/dl.
Another enzyme, ferrochelatase, is also inhibited at low
						blood lead levels. Inhibition of ferrochelatase leads to increased free
						erythrocyte protoporphyrin (FEP) in the blood which can then bind to zinc to
						yield zinc protoporphyrin. At a blood lead level of 50 [MICRO]g/dl or greater,
						nearly 100% of the population will have an increase in FEP. There is also an
						exponential relationship between blood lead levels greater than 40 [MICRO]g/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, it is Cal/OSHA's position that these enzyme disturbances are early
						stages of a disease process which may eventually result in the clinical
						symptoms of lead poisoning. Whether or not the effects do progress to the later
						stages of clinical disease, disruption of these enzyme processes over a working
						lifetime is considered to be 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 associated with a wide array of symptoms including dizziness, fatigue,
						and tachycardia when more severe. Studies have indicated that lead levels as
						low as 50 [MICRO]g/dl can be associated with a definite decreased hemoglobin,
						although most cases of lead-induced anemia, as well as shortened red-cell
						survival times, occur at lead levels exceeding 80 [MICRO]g/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.
2. 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 first manifest
						themselves in the form of 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, cardiorespiratory arrest, and death within 48 hours.
While there is disagreement about what exposure levels
						are needed to produce the earliest symptoms, most experts agree that symptoms
						definitely can occur at blood lead levels of 60 [MICRO]g/dl whole blood and
						therefore recommend a 40 [MICRO]g/dl maximum. The central nervous system
						effects frequently are not reversible following discontinued exposure or
						chelation therapy and when improvement does occur, it is almost always only
						partial.
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 workers with
						blood lead levels as low as 50 [MICRO]g/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 blood lead levels greater than 50
						[MICRO]g/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.
						Whether these effects occur at levels of 40 [MICRO]g/dl is undetermined.
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.
3. Gastrointestinal. Lead may also affect the
						gastrointestinal system producing abdominal colic or diffuse abdominal pain,
						constipation, obstipation, diarrhea, anorexia, nausea and vomiting. Lead colic
						rarely develops at blood lead levels below 80 [MICRO]g/dl.
4. Renal. Renal toxicity represents one of the most
						serious health effects of lead poisoning. 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 Ca-EDTA
						mobilization test has been used to differentiate between lead-induced and other
						nephropathies, but this procedure is not widely accepted. A form of Fanconi
						syndrome with aminoaciduria, glycosuria, and hyperphosphaturia indicating
						severe injury to the proximal renal tubules is occasionally seen in
						children.
5. Reproductive effects. Exposure to lead can have
						serious effects on reproductive function in both males and females. In male
						workers 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. Teratospermia has been noted
						at mean blood lead levels of 53 [MICRO]g/dl and hypospermia and athenospermia
						at 41 [MICRO]g/dl. Furthermore, there appears to be a dose-response
						relationship for teratospermia in lead exposed workers.
Women exposed to lead may experience menstrual
						disturbances including dysmenorrhea, menorrhagia and amenorrhea. Following
						exposure to lead, women have a higher frequency of sterility, premature births,
						spontaneous miscarriages, and stillbirths.
Germ cells can be affected by lead and cause genetic
						damage in the egg or sperm cells before conception and result in failure to
						implant, miscarriage, stillbirth, or birth defects.
Infants of mothers with lead poisoning have a higher
						mortality during the first year and suffer from lowered birth weights, slower
						growth, and nervous system disorders.
Lead can pass through the placental barrier and lead
						levels in the mother'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. Blood lead
						levels of 50-60 [MICRO]g/dl in children can cause significant neurobehavioral
						impairments and there is evidence of hyperactivity at blood levels as low as 25
						[MICRO]g/dl. Given the overall body of literature concerning the adverse health
						effects of lead in children, Cal/OSHA feels that the blood lead level in
						children should be maintained below 30 [MICRO]g/dl with a population mean of 15
						[MICRO]g/dl. Blood lead levels in the fetus and newborn likewise should not
						exceed 30 [MICRO]g/dl.
Because of lead's ability to pass through the placental
						barrier and also because of the demonstrated adverse effects of lead on
						reproductive function in both the male and female as well as the risk of
						genetic damage of lead on both the ovum and sperm, Cal/OSHA recommends a 30
						[MICRO]g/dl maximum permissible blood lead level in both males and females who
						wish to bear children.
6. Other toxic effects. Debate and research continue on
						the effects of lead on the human body. Hypertension has frequently been noted
						in occupationally exposed individuals although it is difficult to assess
						whether this is due to lead's adverse effects on the kidney or if some other
						mechanism is involved. Vascular and electrocardiographic changes have been
						detected but have not been well characterized. Lead is thought to impair
						thyroid function and interfere with the pituitary-adrenal axis, but again these
						effects have not been well defined.
III. Medical Evaluation
The most important principle in evaluating a worker for
						any occupational disease including lead poisoning is a high index of suspicion
						on the part of the examining physician. As discussed in Section
						2, 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 a worker's employment can result in exposure to lead. The
						worker 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 worker may not know of any exposures to lead but
						the suspicion might be raised on the part of the physician because of the
						industry or occupation of the worker. Potential occupational exposure to lead
						and its compounds occur in many occupations in the construction industry,
						including demolition and salvaging operations, removal or encapsulation of
						materials containing lead, construction, alteration, repair or renovation of
						structures containing lead, transportation, disposal, storage or containment of
						lead or lead-containing materials on construction sites, and maintenance
						operations associated with construction activities.
Once the possibility for lead exposure is raised, the
						focus can then be directed toward eliciting information from the medical
						history, physical exam, and finally from laboratory data to evaluate the worker
						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
						job description, exposure to fumes or dust, known exposures to lead or other
						toxic substances, a description of any personal protective equipment used, and
						previous medical surveillance should all be included in the worker'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 a worker 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 medical conditions, current
						medications including proprietary drug intake, 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 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 worker 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. Cardio-pulmonary - 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, easy fatigability, 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 worker's weight
						and blood pressure should be recorded and the oral mucosa checked for
						pigmentation characteristic of a possible Burtonian or lead line on the
						gingiva. It should be noted, however, that 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 congestive heart failure. Pulmonary status should be addressed
						particularly if respirator protection is contemplated.
As part of the medical evaluation, the interim 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 level.
In additional to the above, the physician is authorized
						to order any further laboratory or other tests which he or she deems 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 blood lead level 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 has several advantages over the blood lead level. Because of its
						relatively recent development and the lack of extensive data concerning its
						interpretation, the ZPP currently remains an ancillary test.
This section will discuss the blood lead level 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.
The blood lead level is a good index of current or recent
						lead absorption when there is no anemia present and when the worker has not
						taken any chelating agents. However, blood lead levels along with urinary lead
						levels do not necessarily indicate the total body burden of lead and are not
						adequate measures of past exposure. 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 blood lead levels 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. Consequently, a high blood lead level may only
						represent recent heavy exposure to lead without a significant total body excess
						and likewise a low blood lead level does not exclude an elevated total body
						burden of lead.
Also due to its correlation with recent exposures, the
						blood lead level 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 which are approved by OSHA. Analysis is to be made
						using atomic absorption spectrophotometry, anodic stripping voltammetry or any
						method which meets the accuracy requirements set forth by the standard.
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, workers with renal insufficiency, whether due to lead or some other
						cause, may have decreased lead clearance and consequently urine lead levels may
						underestimate the true lead burden. Therefore, urine lead levels should not be
						used as a routine test.
The zinc protoporphyrin test, unlike the blood lead
						determination, measures an adverse metabolic effect of lead and as such is a
						better indicator of lead toxicity than the level of blood lead itself. The
						level of ZPP reflects lead absorption over the preceding 3 to 4 months, and
						therefore is a better indicator of lead body burden. The ZPP requires more time
						than the blood lead to read significantly elevated levels; the return to normal
						after discontinuing lead exposure is also slower. Furthermore, the ZPP test is
						simpler, faster, and less expensive to perform and no contamination is
						possible. Many investigators believe it is the most reliable means of
						monitoring chronic 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.
An elevation in the level of circulating ZPP may occur at
						blood lead levels as low as 20-30 [MICRO]g/dl in some workers. Once the blood
						lead level has reached 40 [MICRO]g/dl there is more marked rise in the ZPP
						value from its normal range of less than 100 [MICRO]g/dl100 ml. Increases in
						blood lead levels beyond 40 [MICRO]g/100 g are associated with exponential
						increases in ZPP.
Whereas blood lead levels 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.
It is recommended that a hematocrit be determined
						whenever a confirmed ZPP of 50 [MICRO]g/100 ml whole blood is obtained to rule
						out a significant underlying anemia. If the ZPP is in excess of 100
						[MICRO]g/100 ml and not associated with abnormal elevations in blood lead
						levels, the laboratory should be checked to be sure that blood leads were
						determined using atomic absorption spectrophotometry anodic stripping
						voltammetry, or any method which meets the accuracy requirements set forth by
						the standard by an OSHA approved laboratory which is experienced in lead level
						determinations. Repeat periodic blood lead studies should be obtained in all
						individuals with elevated ZPP levels to be certain that an associated elevated
						blood lead level has not been missed due to transient fluctuations in blood
						leads.
ZPP has a characteristic fluorescence spectrum with a
						peak at 594 nm which is detectable with a hematofluorimeter. The
						hematofluorimeter is accurate and portable and can provide on-site,
						instantaneous results for workers 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 2 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. Nevertheless, the ZPP
						promises to be an important diagnostic test for the early detection of lead
						toxicity and its value will increase as more data is collected regarding its
						relationship to other manifestations of lead poisoning.
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 dehydrase (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;
						levels may exceed 5,000 [MICRO]g/1 in the urine in lead poisoned individuals,
						but its correlation with blood lead levels 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.
Summary. The standard for inorganic lead in the
						construction industry places significant emphasis on the medical surveillance
						of all workers exposed to levels of inorganic lead above 30
						[MICRO]g/m3 TWA. The physician has a fundamental
						role in this surveillance program, and in the operation of the medical removal
						protection program.
Even with adequate worker education on the adverse health
						effects of lead and appropriate training in work practices, personal hygiene
						and other control measures, the physician has a primary responsibility for
						evaluating potential lead toxicity in the worker. 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 the
						physician a better understanding of the OSHA standard with the ultimate goal of
						protecting the health and well-being of the worker exposed to lead under his or
						her care.