Washington Administrative Code › Title 296 - Labor and Industries, Department of › Chapter 296-155 - Safety standards for construction work › Part B-1 - OCCUPATIONAL HEALTH AND ENVIRONMENTAL CONTROL › Section 296-155-17654 - Appendix C to WAC 296-155-176 - Medical surveillance guidelines

Current through Register Vol. 24-14, July 15, 2024
(1)
Introduction
The primary purpose of the Washington Industrial Safety and
				  Health Act of 1973 is to assure, so far as possible, safe and healthful working
				  conditions for every working person. 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 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.
Subsection (2) 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 DOSH's position
				  on prophylactic chelation therapy are also included in this subsection.
Subsection (3) 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.
Subsection (4) 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 subsection (3).
Subsection (5) 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.
(2)
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 must 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 6 months of
				  exposure and every 6 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 subsection (4) 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 reach 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 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
				  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 8 hour TWA exposure to lead of
				  30 [MICRO]g/m3 when their 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 their job status depends on a
				  worker's blood lead level declining to 40 [MICRO]g/dl.
As part of the 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
				  determinations 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 their 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 eighteen 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, they can make an
				  appointment with a physician of their 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 their 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 must 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, DOSH 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
				  present, 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 nephropa-thies. 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
				  director. 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.
(3)
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 DOSH 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 5 developmental stages: Normal, physiological changes of
				  uncertain significance, patho-physiological 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. DOSH's development of the lead standard focused on
				  pathophysiological changes as well as later stages of disease.
(a)
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-amino-levulinic 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 DOSH'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 reticulocyto-sis
				  along with the presence of basophilic stippling, and ringed sideroblasts,
				  although none of the above are pathognomonic for lead-induced anemia.
(b)
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,
				  electromyo-graphical 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.
(c)
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.
(d)
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 fibro-sis 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.
(e)
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 (terato-spermia),
				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 asthenospermia 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 amen-orrhea. 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, DOSH 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, DOSH recommends a 30
				  [MICRO]g/dl maximum permissible blood lead level in both males and females who
				  wish to bear children.
(f)
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.