Document gDE8YQKd4yKZVpOXzBy6onjxN

June SO. 1949 Dr. H* Briefer? Associate Professor and Director# Division of Indiirrcria'i Medicine# file Jefferson Medical College of Philadelphia1, 1025 Valnut Street# PMladelpMa# Pennsylvania. Dear Doctor Bidegers I shall undertake to answer your question concerning:the collection of samples of urine. 5his is a difficult problem, and# as you have indicated# it has olagued a number of people# including Doctor Hamlin and his analyst, since# in my,opinion# they have not taken tin trouble to consider carefully the physiological and clinical factors involved. The variability of spot samples of urine# with respect to their lead content# is quite high Certain known 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. Tills 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. Thus# for example# if a reliable person will follow instructions for the collection of a sample of urine at his home# excellent results can. be obtained, he have been doing this for years with certain groups of-men# and the results are ..reliable to a remarkable degree. The workman in a lead trade bathes and changes his clothing before going . home# and then returns to the plant# where he changes into his work clothing, putting iris personal clothing in a clean locker.in the clean part of the lockei^roosw Such a person# if he is careful# is actually clean#!and if.he exercises reasonable caution# can obtain samples free of contamination* e have him collect Ms urine in a. gallon jug which is. delivered to Ms, home, sealed in . a . paper bag#, and which, is returned .to the bag after every use. h.en he lias voided-2 1/2 to 5 liters of urine# the sample is ready for delivery to 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 Ms work clothing. I enclose herewith instructions which'we. issue, to. men for the collection of such samples* These written instructions are supplemented by- a Verbal idiscussion in which every effort is made to impress upon the man the necessity for care in Ms own interest. e use such samples taken periodically from a representative group of persons in every occupation in a plant# for the purpose of measuring the current control of lead exposure. DrV II. Brieger - (2) - dime 20, 1949 A variant of this procedure, when samples of large volume cannot he obtained, or when#for some reason#it is desirable to omit them,# consists in collecting .spot ,*smaplos under carefully controlled conditions with respect to cleanliness of the man and surroundings. If ~ic arc interested primarily in the general level of lead abs orca tion on the part of a group of individuals with homogeneous employ ment j, we obtain one sample from each of a number of persons. I lie 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 persons' 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 range of 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. hen# 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 we 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 may be-guite -high# while at the same time his urinary excretion of lead mayyconsistently low* This is a very unusual situation# but it does occur# and therefore in the individual case one must always be on, the look-out for it. On the other hand# the effects of slight or moderate lead exposure are-revealed by the analysis o-f the Uribe much more clearly and; consistently# than by analysis cf the (-^materials# obtained in two totally different ways, one can discern. \ clearly# discrepancies which mby point to the contamination of one j or the other of the samples. Ail of these considerations are highly ^important for diagnostic and medico-legal purposes# and a great ideal of our medical confusion is based on the fact that an increased number of people are making analyses on various materials without having the foggiest idea of the physiological considerations on willed the interpretation of such analytical results must depend. This is Where Hamlin and his analyst find themselves # for I am' sure from tfcaji cursory examination of their data that they are confused by physiolojgical 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 oh.their part to ignore wjhat they regard; as aberrant' clinical f'iMihgl have led KE- 0019999 Dp, H. Brieger - (p) - Jime 20. 1949 them to conclude, that safety , in terms of lead excretion, can be-, defined on a much higher level than that vhich T.re have given.__ I make this statement deliberately and on good evidence, since j . studied with oc-iioudorable care the original analytical and clinical daoa ci or:e of their papers * Thei% is a dangerous viewpoint in terms of the present hazards in the lead trades since it is an honesv opinion, while at the sane tine being a source of justifi cation to a number of people who feel that their efforts in safe guarding their employees arc adequate. Sincerely yours. Bm. ef xuXXO.* Ro!DertJ,"St iCeHoe 7"irr UT vr 0020000