Not in excess of 0.5 mg/m3 Any dust and mist respirator, except single-use, Not in excess of 1 mg/m3 Any dust and mist respirator, except single-use respirator or quarter mask. Any fume respirator or high efficiency particulate filter respirator. Not in excess of 5 mg/m^A ny supplied-air respirator. Any self-contained breathing apparatus. A high efficiency particulate filter respirator with a full facepiece. Any supplied-air respirator with a full facepiece. Any self-contained breathing apparatus with a full facepiece. Not in excess of 100 mg/m^ A powered air-purifying respirator with a high efficiency particulate filter.standard, enviromental levels shall be monitored every 3 months. This increased frequency of monitoring shall be continued at least 6 months (i.e. two more quarterly monitoring periods) after the last sampling that demonstrated levels at or above the environmental limit. Periodic environmental sampling shall be performed to coincide with periodic biologic sampling, i.e. shall be performed within 2 weeks of biologic sampling.Breathing zone samples shall be collected to permit construction of a timeweighted average exposure for every operation.- (b) Records shall be maintained for all sampling schedules to include the sampling methods, analytical methods, type of respiratory protection in use (if applicable), and the concentrations of inorganic lead in each work area. Records shall be maintained so that they can be classified by employee. Each employee shall be able to obtain information on his own environmental exposure. (c) Medical records shall include information on all biologic determinations and of all required medical examinations. These records shall be kept for at least 30 years following the last occupational exposure to inorganic l e a d . *Guidance for establishing worker exposure measurements are given in DHEW(NIOSH) Publication No 77-173, Occupational Exposure Sampling Strategy Manual, available from the Division of Technical Services# I. REVISED RECOMMENDATION FOR AN INORGANIC LEAD STANDARD
The
Procedures for sampling and analysis of blood for lead shall be as described in Appendix II, or by any method shown to be equivalent in precision and accuracy.
All workers subject to "exposure to inorganic lead" shall be offered biologic monitoring at least every 6 months. The schedule of biologic monitoring may be made more frequent if indicated by a professional industrial hygiene survey.
If environmental sampling and analysis show that environmental levels are at or greater than the recommended environmental levels, the Interval of biologic monitoring shall be halved, I.e. blood analysis shall be conducted quarterly. This increased frequency shall be continued for at least 6 months after the high environmental level has been shown.
If a blood lead level of 0.060 mg Pb/100 g or greater is found, and confirmed by a second sample to be taken within two weeks, steps to reduce absorption of lead shall be taken as soon as the high levels are confirmed.
Steps to be considered should include improvement of environmental controls, of personal protection or personal hygiene, and use of administrative controls.
A medical examination for possible lead poisoning shall be made available to workers with unacceptable blood lead levels. Engineering controls shall be used wherever feasible to maintain inorganic lead concentrations at or below the prescribed limits.
Compliance with the prescribed limits by the use of respirators is allowed only when inorganic lead concentrations are in excess of the workplace environmental limit because required engineering controls are being installed or tested, when nonroutine maintenance or repair is being accomplished, or during emergencies. Appropriate respirators as described in Table 1-1 shall only be selected and used pursuant to the following requirements:
(1) For the purpose of determining the class of respirator to be used, the employer shall measure the atmospheric concentration of inorganic lead in the workplace initially and thereafter whenever process, worksite, climate, or control changes occur which are likely to increase the inorganic lead concentration.
(2) The employer shall ensure that no employee is exposed to inorganic lead above the recommended limit because of improper respirator selection, fit, use, or maintenance.
(3) Employees experiencing breathing difficulty while using respirators shall be referred to a physician for evaluation. This evaluation should investigate if the employee has adequate ventilatory capacity, any evidence of obstructive lung disease, and the employees ability to use negative or positive pressure respirators. (5) The employer shall provide respirators in accordance with the Table 1-1, below and shall assure that the employee uses the respirator provided at all times when the concentration of inorganic lead exceeds the permissible limit.
(6) If both fume and dust are present, the recommended usage is that for fume. (7) The employer shall provide respirators in accordance with  (2) Respirators shall be available for wearing during evacuation procedures if long distances need to be traversed; supplied air respirators shall be available for employee use where equipment or operations cannot be abandoned.

# (b) Exhaust Systems
Where a local exhaust ventilation and collection system is used, it shall be designed and maintained to prevent the accumulation of lead dust and fume.
(1) Hazardous types of exposure should not be scattered throughout a plant but, rather, concentrated in a single area where special control procedures can be utilized.
(2) Air from the exhaust ventilation systems shall not be recirculated into the workroom, and should not be discharged outside the plant so as to create an air pollution problem.

# (c) General Housekeeping
(1) Vacuuming shall be used wherever practicable and no dry sw ^eping or blowing shall be performed. The refining and processing necessary to form these products include heating, grinding, and volatilization and therefore produce potentially hazardous industrial atmospheres. The impression should not be left that all workers in these industries are jeopardized, but rather that such uses of lead places them at risk of lead absorption. The prevalence of lead poisoning in ancient times is speculated upon, and it has been suggested that Rome fell because of the prevalence of lead III-2 poisoning (plumbism) in its citizens.
It seems likely that, with the ignorance that existed on the hazards of lead and on methods of limiting exposure, there was a significant incidence of plumbism until Its recognition in recent times generated preventive procedures. There was a non-significant increase in chest disease among older retired workers, attributed to other causes, since most of these pensioners lived in an urban area with a higher rate of death from chest disease than that in the country as a whole.

# Effects on Humans

# Concentrations of lead
In blood are expressed as weight units (such as mg) per 100 ml or 100 g of whole blood.
European workers more commonly express blood lead as weight units per 100 ml of blood, while American workers more commonly express blood lead as weight units per 100 g of blood.
This document will follow the American custom except In referring to studies reporting blood lead in weight units per 100 ml.
The difference between the two expressions Is small, about 5% or less.
Thus, a blood lead concentration of 0.080 mg/100 g would be equivalent to about 0.084 mg/100 ml.

# III-8
Unlike the findings of earlier investigators (Dingwall-Fordyce and Lane,    APPENDIX II.
and

# DITHIZONE METHOD OF ANALYSIS OF LEAD IN AIR AND BIOLOGIC SAMPLES*
The Phenol Red -0.1% aqueous solution.
Ashing Aid Acid -Dissolve 25 g potassium sulfate in sufficient redistilled concentrated nitric acid to make 1 0 0 ml.

# VIII-6
White Petrolatum -Supplied in a glass jar, for greasing stopcocks.
To check on the purity, put a pinch of this petrolatum in a beaker, add a few milliliters of the standard dithizone and swirl. If the dithizone is no longer green after a few minutes, the material is unsatisfactory for greasing stopcocks.

# APPARATUS
Set the instrument at zero absorbance using the zero lead standard solution.
Read the absorbances of the samples and of the reagent blank.
V III-11                        (3) 0.5 ml of blood plus 4.5 ml of 2% Triton X (4) 0.5 ml blood plus 1.0 ml of Unisol. Let the mixture stand overnight, then add 3.5 ml of doubly distilled water              It is unlikely that we will soon be able to fully evaluate the contribution of the many factors involved in lead poisoning. Thus far, it is known that dietary sources, physiological state, age, sex, and parameters of exposure conditions (e.g., solubility, particle size) are all involved in the production of lead intoxication.

# and finishing machines such as saws, bevelers, planers and routers

# Adapted from reference ^ REPRESENTATIVE LEAD EXPOSURE IN PRINTING OPERATIONS

# Subacute and Chronic Toxicity of Inorganic Lead (Cont'd)
Animal
Properly designed studies may be able to more fully characterize these relationships, while also identifying situations where individuals may be at increased risk of poisoning.

# VIII. RESEARCH NEEDS X I -68
The literature search strategy employed in preparing this update consisted of both computerized and manual techniques. Major reliance for bibliographic information was placed on a computer-generated NIOSHTIC search.
In order to supplement this citation source, several steps were taken to insure that:
(1 ) all relevant articles would be retrieved, and (2 ) very recent articles of relevance to the literature review would not be overlooked.
An on-line search using lead and related keywords (e.g., plumbism, pica, ALAD, protoporphyrin) was undertaken using the following data bases:

# V-10

# VI. REFERENCES
Westerman and coworkers  were not able to correlate lead absorption with the development of multiple sclerosis in humans.

# Renal Damage
Occupational lead nephropathy in adults is a relatively uncommon occurrence in the United States and, thus far, has been poorly characterized in its pathogenesis. However, recent studies have suggested that chronic lead nephropathy may be going unrecognized due to a lack of correlation with blood lead concentrations. An excessive incidence of kidney dysfunction (elevated blood urea nitrogen and creatinine) was found among lead plant workers [1 1

# Intratracheal injection

# Se i z u r e s ob s e r v e d in lead-treated adu l t s a l o n g w i t h g e n eralized 172 c e rebral edema of the wh i t e matt e r and focal cortical necroses, p r o b a b l y d u e to epi leptic convulsions.
In the infant, generalized edema of the wh i t e mat t e r w a s observed; the animal died on day 117.

# 09-IX

# ppm lead a s lead a c e t a t e f r o m a g e 6 to 18 w e e k s fed wi t h a c a lciuma n d -p h o s p h o r u s -l o w purified diet

# Cyclic response m a n i fested as an initial anorexic phase (first 4 weeks) followed by an accI i m a t i z a t i o n phase (weeks 4 to 7) and a terminal debil i t a t l v e cachectic stage (after c o n s u m i ng 191 mg lead/kg body weight). S ignificant anemia, leukopenia, and n ormoblastocytosis w i t h i n 6 weeks. A l s o present w e r e nonspecific serum en z y m e alterations, hydropic d e g e n e r a t i o n of s p e r m a t o gonia, and h i s t o p a t h ologic c h a n g e s in

# Increased blood and ur i n e lead levels. Increased urinary A L A excretion, a n d d e c reased eryth r o c y t e A L A D a c t i v i t y in all groups.
No effect on   d e c r e a s e d AT P a s e a c

# Harked r ed u c t i o n in e r y t h r o cyte A L A D activ i t y but no changes in l evels of exc r e t e d h eme precursors. No c h a nges detected in se r u m che m i s t r y or hematology; no h i s t o p athologic damage.

# Ibb

# Signs of hema t o l o g i c a l t e r a t i o n not evident before 8 weeks. Effects included dep r e s s e d o x i d a t i v e a c t i v i t y in reticulocytes and

# XII-20 D E P A R T M E N T OF HEALTH, EDUCATION, A N D W E L F A R E PUBLIC HEALTH SERVICE C E N T E R F O R D I S E A S E C O N T R O L N A T I O N A L I N S T I T U T E F O R O C C U P A T I O N A L S A F E T Y A N D H E A L T H R O B E R T A. T A F T L A B O R