Subpart Z
Inhalation of 1,3-butadiene (BD) primarily increases the risk of blood cancers (like leukemia and lymphoma) and may damage reproductive organs and the fetus. This is stated in 1910.1051 App C, which explains BD’s toxicology and epidemiology showing links to lymphohematopoietic cancers and reproductive toxicity.
Acute inhalation of BD can irritate the eyes, nose, throat and lungs and at very high concentrations can cause narcosis, breathing paralysis, unconsciousness, or death. The guidance in 1910.1051 App C lists those acute effects and notes that severe acute exposures may require hospitalization and focused exams of the respiratory system, eyes, skin and nervous system.
BD exposure is associated with potential reproductive toxicity, including effects on sperm and ovarian/testicular atrophy in animal studies, so workers with high exposure who have trouble conceiving, miscarriages, or stillbirths should receive medical and laboratory fertility evaluation. See 1910.1051 App C for guidance that physicians should identify and provide appropriate reproductive consultations and exams.
The health questionnaire for workers exposed to BD must be updated at least once every year. 1910.1051 App C states that after the initial administration the questionnaire should be repeated annually to elicit new signs, symptoms, or history related to lymphohematopoietic disorders or reproductive problems.
An annual complete blood count (CBC) with differential and platelet count is required for each employee with BD exposure. 1910.1051 App C specifies that the CBC should be analyzed by an accredited laboratory and may be drawn from venous phlebotomy or, if technically feasible, a fingerstick capillary sample.
Yes — 1910.1051 App C allows CBC samples to be obtained by venous phlebotomy or, if technically feasible, from a fingerstick capillary blood sample; either must be analyzed by an accredited laboratory.
The examining physician or other licensed health care professional (or medical specialist) is responsible for deciding whether a CBC abnormality is clinically significant, and a clinically significant abnormal CBC should lead to removal of the employee from further BD exposure. This process is described in 1910.1051 App C. Employers should follow the clinician’s recommendation, which may include temporary transfer to BD‑free duties.
Small CBC changes only slightly outside population-based normal ranges may not require immediate concern; clinicians should use clinical judgment, compare with prior CBCs for trends, and when appropriate repeat the CBC within about 6 weeks to see if values return to normal. This guidance comes from 1910.1051 App C.
After a severe acute BD exposure, a CBC should be obtained within 48 hours and then repeated at one, two, and three months. 1910.1051 App C specifies this timeline because acute exposures can increase the risk of blood abnormalities.
An initial physical examination is required and then repeated every three years for workers exposed to BD. 1910.1051 App C also states that additional exams should be done as needed for questionnaire responses, abnormal CBCs, reproductive concerns, or after acute exposures.
The physical exam should establish baseline general health and look for signs of lymphohematopoietic disorders (for example, enlarged lymph nodes, splenomegaly, or hepatomegaly) and update those findings on repeat exams. This is described in 1910.1051 App C.
Workers who will no longer be working in BD-exposed jobs should receive a physical examination to rule out lymphohematopoietic disorders before or soon after leaving BD exposure. 1910.1051 App C recommends this to document health status and identify any disorders that could be related to BD.
The health questionnaire's main role is to identify symptoms and personal or family histories (such as immune deficiency, blood disorders, prior exposures to hematopoietic toxins, or reproductive difficulties) that raise a worker’s risk for leukemia, lymphoma or reproductive effects. 1910.1051 App C emphasizes annual updates and referral for appropriate medical follow-up based on responses.
Yes — 1910.1051 App C suggests including a flowsheet of laboratory values in each employee’s medical record so trends and substantial changes over time can be easily identified by clinicians.
Yes — CBC abnormalities can result from many causes (viral illness, recent blood donation, menstruation, lab error, etc.), so clinicians should consider these possibilities, compare to prior CBCs, repeat testing within about 6 weeks if appropriate, and use clinical judgment to decide on removal from exposure. This is explained in 1910.1051 App C.
Physical exams and consultations for reproductive concerns should be offered when the physician identifies a need—particularly for workers with high BD exposures or those reporting infertility, miscarriages, stillbirths, or other reproductive problems. 1910.1051 App C advises healthcare professionals to provide reproductive-focused assessments when indicated.
The appendix titled "Medical Screening and Surveillance for 1,3-Butadiene" is non-mandatory guidance that supports compliance with the BD standard; it provides recommended medical program elements rather than binding regulatory text. See 1910.1051 App C and the main BD rule at 1910.1051 for the regulatory requirements.
If an individual shows a substantial change in their own CBC compared with prior personal measurements — even if still within population norms — clinicians should treat it as potentially abnormal, document and trend it (for example with a flowsheet), and consider further evaluation or removal from BD exposure if clinically indicated. 1910.1051 App C recommends comparing to the employee’s prior CBCs to detect meaningful changes.
Physicians or other licensed health care professionals should perform and interpret the medical screening, and they are responsible for evaluating symptoms of lymphohematopoietic disorders and determining clinical significance of test results. 1910.1051 App C specifies that these licensed professionals handle diagnosis, follow-up and referrals.
Workers who suffer severe acute BD exposures and are hospitalized should receive focused medical management and a CBC within 48 hours, followed by repeat CBCs at one, two, and three months, as recommended in 1910.1051 App C because acute exposures increase the risk of blood abnormalities.