Document 2G0kR78dX4z5849K9VO6oB5b

June 20. 19 k 9 Dr* E* Brieger, AssociateBrofessor. and' Director ' Division of Industrial Medicine# [.:22c Jefferson Medical College of B b H a d e l p M a > 1025 Walnut Street, ' ?hi lad eIp Ilia, Pennsylvania. Dear Doctor Eriegcr* I shall undertake to answer your question codcernixig tlie collection bf samples of urine. This is a difficult problem, and, as you have indicated, it has plagued, a number of people, Including Doctor Hamlin and his analyst, since, in my, opinion, they have not taken the trouble to consider carefully the physiological and clinical factors involved. The variability of spot samples of urine, wit h respect to their lead content, is quite high. Certain iaiomi factors enter .into . this, of which the most important is the relative rate of water excretion. Attempts have been made to correct for this variation .by measuring the specific gravity and making a calculation .based thereon. This procedure, we believe to be unsatisfactory for physiological reasons, although the specific gravity can be used very roughly to interpret the significance of the analytical findings. The variability due to spot, sampling, can bo eliminated largely by the collection of large samples of urine. T h u s , 'f o r example, if a reliable person will follow instructions for the collection of a sample of urine at his home, excellent results can be obtained, lie have been doing this for years wi t h certain groups of:-men, and the results are,reliable to a remarkable degree. The workman in a lead trade bathes and changes his clothing bef ore going .h o s e , and then returns to the plant, where he changes into his work clothing, putting his personal clothing in a clean locker.in the . clean part of the lookei^room. S u c h a person, if he is careful, is actually clean,!and if he exercises reasonable caution, can obtain samples free of contamination We have him collect his urine in a. gallon jug which Is. delivered to Iris, home sealed in :a . paper bag,, and which is returned .to the bag after every use, . When he lias- voided* 2 if2 to 3 liters of urine, the sample is ready for delivery t o :the laboratory, and this isdone by having the samples collected by a person responsible to the Laboratory. Under suitable circumstances the employee himself can deliver the sample to the Laboratory before he changes back into his work clothing*. I enclose herewith instructions which we issue to men for the collection of sue]', samples * These written instructions are supplemented b y a verbal discussion in \rliich every effort is made to impress upon the m a n the necessity for care in ills own interest. Tie use such samples taken periodically from a representative group of persons in every occupation in a plant, for the purpose of measuring: the current' c o n t r o l o f 1lead- exposure. " ` . 0019998 Dr* II. Spiegei9 - (2) - dime 20, 1949 A variant of this procedure, when samples of large volume cannot; he obtained, o p when#fop some reason#it is desirable to omit then# consists in collecting spot samples under carefully controlled conditions v respect to cleanliness of the man and surroundings, If -re interested rrinarlly in the general level of lead absorp- tion on the part of a'group of individuals with homogeneous employ*, ment# we obtain one sample fron each of a number of persons. Ihe variability of the results under these conditions will equalize itself# and ve will be able to see the overall order of magnitude of the occupational hazard from a study of the combined results. Actually the mean value of samples of small volume, will bo approximately the same as the mean value of samples of large volume, if a proper number of persons1 is represented in the sampling program.* The only difference that will exist will be that results both higher and lower will be obtained in the series of camples of small volume. That is# the range of values will exceed the r-anse ofp - p i r p - ir - - * h values ** *->* of large samples* Now all of the above relates to the measurement of occupational lead exposure periodically. For this purpose the results are reliable whether obtained from samples of large volume or small.. When, however# one wishes to determine the status of an individual# either for his safety or for diagnostic purposes# it is absolutely necessary to have more than one sample* Also it is desirable# for physiological and pathological reasons ,to sample more than one material* For this reason in diagnostic- work wc always obtain a sample or samples of blood and a sample or samples of urine. The combined results on -these two materials will tell you everything that can be learned# and there is no other way# short of sacrificing the man and analysing his tissues# of determining those facts. For example # the lead concentration in the blood in a given individual m a y be quite high, while at the same- time his urinary excretion of lead maytconsistently low* This is a very unusual situation# but it does occur# and 'therefore in the., individual case one must always be on tljie look-out for it. On the other hand, the effects of slight or moderate lead exposure are-; revealed by the analysis 0 ** the urifte much more clearly and: consistently# than b y analysis of the -^materials, obtained in two totally different ways# one can discern, clearly; discrepancies w h i c h m dy point to; the contamination of one ' or the other of the samples* All! of these considerations are highly ^Important for diagnostic and medico-legal purposes# and a great deal of our medical confusion is based on the fact that an increased number of people are n a M h g analyses on various materials without Ihaving; the foggpLest idea of the physiological considerations on which the interpretation of such analytical results must depend, This is Where Hamlin and his analyst find themselves, for I am' sure from thoj cursory examination of their data that they are confused b y physiological variation;# plus not infrequent contamination of their samples # plus irregular: analytical results obtained by a method which has a rather large error* The combination of these errors and the inevitable variability plus a willingness on their part to ignore what they regard; as aberrant" clinical findings have led K6 0019999 Dj?,. H. Br ie ge a ? (p ) - Ju n e 2 0 - 19^ 9 them to conclude t h at safety,- in terns of lead excretion, can be> defined on a much. higher level than that chicli 're have given. 1 sake this, statement deliberately and on good evidence, since j. studied vi t h coiusudcrahle care the original analytical and clinical dava cf one of their papers * T'beiate is a dangerous viewpoint In terns of: the present hazards in the lead trades since it is an honesv opinion, ubile at the sane tine being a source of inetifi cavi on to a number of people who feel that their efforts in safe guarding their employees1arc adequate. Sincerely yours, BoDeriTXT n elioe