a description of the preferred embodiments of the present invention will now be presented with reference to fig1 - 10 . a portion of the method of the present invention has been disclosed in a publication of the inventors , &# 34 ; dna uvb dosimeters &# 34 ; ( j . photochem . photobiol . b : biology 31 , 57 - 61 , 1995 ), the enntire disclosure of which is incorporated herein by reference . while the discussion to follow details a uvb dosimeter , it is to be understood that this is not intended to be limiting , as the other types of radiation discussed above are intended to be subsumed within the scope of this invention . the device , a first embodiment of which is shown in fig1 a , is assembled as outlined in fig8 and comprises a dosimeter 10 for measuring an incident dosage of uvb radiation . the dosimeter 10 comprises a first support sheet 12 of aclar ™ uv - transparent plastic film ( allied signal , pottsville , pa . ), which transmits 92 % of light above 250 nm . onto this sheet 12 are placed a plurality of spots 50 of λ dna ( block 601 ) ( new england biolabs , 500 μg / ml ) that has been diluted with te buffer 10 mm tris - hcl ( ph 8 . 0 ) and 1 mm edta ! to a desired concentration , as measured with a spectronic 601 uv spectrophotometer ( milton roy , rochester , n . y .). in a preferred embodiment , a total of 8 spots 50 , each comprising 5 μl ( 50 ng ) of the λ dna , are placed on the support sheet 12 . λ dna is beneficial for this purpose because its sequence is precisely known , which is necessary for the subsequent damage analysis . in addition , there is a diverse selection of lengths available in amplification products , which in turn provides a variety of exposure times : a longer segment , having a higher number of uv - induced lesions ( on average ), can be used for shorter exposure times ; a shorter segment , having a smaller number of uv - induced lesions ( on average ), can be used for longer exposure times . this particular dna is not meant to be limiting , however , and the invention disclosed herein contemplates the use of other radiation - vulnerable nucleic acids as well . the sheet 12 having the dna spots 50 thereon is then placed in a desiccator having preheated silica gel therein and left for 12 - 15 hours ( e . g ., overnight ) at 40 ° c . ( block 602 ). after drying , a second , covering sheet 14 of aclar ™ film is placed in covering relation to the support sheet 12 and rubbed to promote the sheets &# 39 ; 12 , 14 adherence together , the dna spots 50 thereby sandwiched therebetween ( block 603 ). the dosimeter 10 is then assembled by cutting the sheet / dna / sheet 12 / 50 / 14 sandwich into two portions , each containing 4 dna spots 50 ( block 604 ). the dosage - measuring component reference numerals will now be primed to distinguish them from the control components , for example , the detection dna spots 50 &# 39 ; and control dna spots 50 . in a preferred embodiment , a sealing means such as a nonreactive silicone 18 , 18 &# 39 ; is applied to the edges of the control sheet / dna / sheet 12 / 50 / 14 and dosage - measuring 12 &# 39 ;/ 50 &# 39 ;/ 14 &# 39 ; sandwiches to provide protection from fluid intrusion ( block 605 ). the effect of silicone 18 on the pcr product was tested and found not to interfere with the pcr amplification process . the dosimeter 10 additionally comprises a housing 20 having a bottom section 202 and a top section 204 . the bottom section 202 may have means for attaching to an object or living being , such as a clip 205 , for ease of use , as are common in x - ray film badges . the top section 204 has a portion 206 situated above the detection dna spots 50 &# 39 ; that is transparent to wavelengths in the range of interest , here generally 290 - 320 nm , and also to high - energy particles desired to be measured . alternatively , the top section 204 may have an opening sufficiently large to permit the dna spots 50 &# 39 ; exposure to impinging radiation and particles . in exemplary embodiments a radiation badge or a 5 cm × 5 cm slide mount may be used as a housing . an assembly is formed by placing between the control sandwich 12 / 50 / 14 and the detection sandwich 12 &# 39 ;/ 50 &# 39 ;/ 14 &# 39 ; a shielding sheet 16 , for example , comprising black plastic , that is impervious to radiation in the wavelength range of interest ( and to high - energy particles desired to be measured with proper shielding ) ( block 606 ). the dosimeter 10 is assembled by placing the assembly between the housing top 204 and bottom 202 sections ( block 607 ), with the control sandwich 12 / 50 / 14 adjacent the housing bottom section 202 . in an alternate embodiment wherein silicone sealant is not used , the housing 20 is preferably watertight . in a particular embodiment the dosimeter 10 , owing to its design as compared with previously known dosimeters , can be made very small , permitting portability , inconspicuousness , and ease of use . such a small size also permits the dosimeter 10 to be used on animals that might not otherwise tolerate wearing a large , bulky , and / or heavy object . affixed to a corner of the housing top 204 in a particular embodiment is a piece of polysulfone film 209 , which darkens upon exposure to uvb radiation ( block 608 ). the polysulfone film 209 is used as an indicator , whereby a darkened condition indicates that the dosimeter 10 has already been exposed to uvb radiation and should be discarded . in an alternate embodiment , such as for underwater use , the dosimeter 30 ( fig1 b ) comprises a unitary aclar ™ film 32 for two - sided collection , whereto the dna detection and control spots 40 &# 39 ;, 40 are adhered . the control spots 40 are shielded , for example , by a radiation - impervious layer , such as a black tape 302 or black paint placed in covering relation to the control spots 40 on both sides of the film 32 . this arrangement permits collection of dose information incident on the dosimeter 30 over 360 °. the dosimeter 10 is irradiated under controlled conditions in a solar uv simulator for a series of times , the dose rate being measured by a photometer . in particular , a jagger meter is covered with one layer of aclar ™ film and two layers of 0 . 13 - mm - thick kodacel ( eastman kodak , rochester , n . y .). the thus - filtered jagger meter is placed in a solar uvb simulator , comprising two fs40 lamps ( westinghouse , pittsburgh , pa .) in parallel alignment on the top to mimic the uvb region of the solar spectrum . uv irradiance ( j m - 2 sec - 1 ) is converted from current ( μamp ). the solar simulator exhibits a spectrum between 290 and 400 nm , with a maximum at 315 nm . the two layers of kodacel film is replaced every 16 h of uv irradiation , as it is solarized with time . for field testing the dna dosimeter is placed vertically at 1 . 5 m above the ground facing south , and the ground around the site was covered with grass ( low albedo ), and no shadowing or shielding was observed during testing . the dosimeter 10 is also exposed to known dose rates of x rays and 60 co , and then calibration is performed by multiplying the known dose rate by exposure time . for dosages of high - energy particles , an accelerator is used for calibration . for irradiation of aqueous λ dna , solutions ( 5 ng μl - 1 ) are placed into wells ( 3 mm diam .× 2 mm depth ) in a acrylic block ( 10 × 8 × 1 cm ) and irradiated with a germicidal lamp ( primary emission at 254 nm ) and with a solar uvb simulator . aclar ™ film is placed over the entire block for the irradiation with the solar simulator . after the irradiation , 6 μl of irradiated λ dna solution ( 5 ng μl - 1 ) from three individual holes is transferred into pcr tubes for comparison with a 30 - ng dried dna dosimeter . for irradiation of standard dried dna through mylar film , in addition to the two layers of kodacel film , a layer of mylar film is placed over the standard , dried dna ( 30 ng ). the mylar film blocks uv radiation below 315 nm . calibration is then accomplished by placing a layer of aclar ™ film , two layers of kodacel , and a layer of mylar over the jagger meter . the dna spots 50 are then analyzed as will be described below to correlate the known dose rate with dna damage . as shown in the flow chart of fig9 the dosimeter 10 is disassembled ( block 901 ), and the control and irradiated covering sheet / dna / support sheet sandwiches 12 / 50 / 14 and 12 &# 39 ;/ 50 &# 39 ;/ 14 &# 39 ; are separated ( block 902 ) to expose the dna spots 50 , 50 &# 39 ;. the dna is then rehydrated ( block 903 ) in 4 μl of distilled , sterilized water , with the solution resulting from three washes of the two sheets comprising 24 μl volume for each of the irradiated and control samples . the solutions are placed in pcr tubes ( perkin elmer , foster city , calif .) for a polymerase chain reaction ( pcr ) assay ( block 904 ), which has already been described ( j . d . regan and h . yoshida , j . photochem . photobiol . b : biology 31 , 57 - 61 , 1995 ). this technique amplifies specific genomic regions in template dna only if the dna is undamaged , that is , if there are no areas having intrastrand dimers , breakage , or cross - linking . a dose - response curve can then be obtained ( block 905 ) by plotting the average lesion frequency per strand per pcr product as a function of dose . a solution of fluorescent dye that binds to a - t - rich regions of double - stranded dna is used to quantify ( block 906 ) pcr products , which is indicative of dose . the combination of the pcr and fluorescence assays is known to be advantageous over other techniques in its nonreliance on radiolabeled dna , its speed , and its sensitivity . the specific protocol is carried out as follows : mix the pcr reagents in a total volume of 50 μl according to table 1 . table 1______________________________________volumes of pcr reagents used for protocol volume ( μl ) final concentration______________________________________h . sub . 2 o 14 . 1510x buffer . sup . a 5dntp ( datp , dctp , 4 200 μm eachdgtp , dttp ). sup . bprimer a . sup . c 1 . 3 1 μmprimer b . sup . c 1 . 3 1 μmtaq polymerase . sup . d 0 . 25 2 . 5 unitslambda dna . sup . e 24 50 ngtotal 50______________________________________ . sup . a gibcobrl , grand island , ny . . sup . b pharmacia biotech , piscataway , nj . . sup . c biosynthesis , inc ., lewisville , tx . . sup . d promega , madison , wi . . sup . e new england biolabs , inc ., beverly , ma . five primer a / b combinations have been detailed , although this is not meant to be limiting ( see fig1 for primer sequences ). a primer 0 / primer 2 combination produces a 230 - bp product ; primer 1 / primer 2 , a 500 - bp pcr product ; primer 2 / primer 4 , a 1080 - bp product ; primer 2 / primer 3 , a 2240 - bp product ; primer 2 / primer 5 , a 4000 - bp product . the pcr protocol for the primer 0 / primer 2 and primer 1 / primer 2 combinations is : the pcr protocol for the primer 2 / primer 4 , primer 2 / primer 3 , and primer 2 / primer 5 combinations is : after the pcr is completed , a gel 2 % agarose , tae buffer ( tris base , 40 mm ; sodium acetate , 20 mm ; edta , 2 mm ), ph 8 . 3 ! is run to identify the pcr products with comparison to a known marker . next the fluorescence of the pcr products is measured by mixing 30 - 40 μl sample in 2 ml dye solution 10 μl of 0 . 1 μg / ml hoechst 33258 solution , 10 . 0 ml of tne solution ( 0 . 2m nacl , 10 mm tris - hcl , 1 mm edta , ph 7 . 4 ), and 90 . 0 ml distilled water ! and measuring the fluorescence at λ exc = 355 nm and λ em = 450 nm with a spectrophotometer ( perkin elmer ls3 ). the fluorescence intensity before pcr is subtracted from the fluorescence intensity after pcr . calibration is accomplished with the use of calf thymus dna ( 1 mg ml - 1 ; hoefer scientific instruments , san francisco , calif . ), diluted to 100 μg ml - 1 to normalize for percentage of a - t as compared with the lambda dna . the fluorescence at λ exc 355 nm and λ em 450 nm was measured with an ls - 3 fluorescence spectrophotometer ( perkin elmer , wilton , conn .). the fluorescence of the pcr mixture before pcr ( background fluorescence ) was subtracted from the fluorescence of the pcr mixture after pcr . spots of solar irradiated 50 &# 39 ; and calibration dna are treated individually to find the amount a d of amplified segment . the control 50 was used to calculate the average amount ( a 0 ) ave of amplified segment . the ratio , a d /( a 0 ) ave is plotted in fig2 for which the pcr was performed 16 times . each pcr experiment with 3 repeats with different amounts of template dna was repeated at least twice on two different days ( n ≧ 6 ). (⋄) 150 ; (▪) 100 ; ( δ ) 50 ; () 30 ng dna . the ratio of fig2 was subjected to a poisson equation - ln a d /( a 0 ) ave ! to obtain the average lesion frequency per 500 bp per strand for the exposed dosimeters ( fig3 a - c ). the process is repeated for statistical accuracy . in fig3 a the average lesion frequency for a 500 - bp segment is plotted as a function of incident dose applied with a solar uvb simulator for (⋄) 150 ; (▪) 100 ; ( δ ) 50 ; () 30 ng dna amounts . the average lesion frequency - ln a d /( a 0 ) ave ! is calculated based on the results of fig2 . in fig3 b the average lesion frequency for a 1080 - bp segment is plotted as for fig3 a , for (∘) 25 , ( δ ) 50 , (□) 100 , and (⋄) 150 ng dried template dna . also shown is the average lesion frequency (∇) for 50 ng dna irradiated with a mylar covering film . in fig3 c the average lesion frequency for a 2240 - bp segment is plotted as for fig3 a , for () 25 , (▴) 50 , (▪) 100 , and (♦) 150 ng dried template dna . also shown is the average lesion frequency (▾) for 50 ng dna irradiated with a mylar covering film . the amount of amplified product in dried dna has been found to be substantially identical to that in aqueous dna for the same amount of unirradiated dna . this indicates that manipulation of the dna , such as rehydration of dried dna and transfer of the rehydrated dna solution from the film to the pcr tubes , does not have any effect on the amplification efficiency . as long as the concentration of primers , mg 2 + ions in the pcr buffer , dntp and the pcr cycles and the ph of the buffer were controlled and fixed , the pcr assay was reproducible . since the effect of self - shielding on dried dna has not been known in the art , four different concentrations of dna were prepared before drying the dna . the same volume ( 5 μl ) was applied onto the films to obtain 30 , 50 , 100 , and 150 ng of dna . although the concentrations of the solution were different , the diameter of the dna solution spotted onto a film was essentially the same (˜ 2 . 5 mm ) irrespective of the concentration . the ratio a d /( a 0 ) ave of amplified product was plotted as a function of dose for the four different initial amounts of template dna applied onto the film ( fig2 ). since any lesion induced by uv irradiation blocks the polymerase from synthesizing the new amplification segment , the amount of amplified product decreases with increasing dose . all four dosimeters with the four different amounts of dna exhibited a single exponential decay over the range of doses investigated . the amount of amplified product was reduced by ˜ 70 % for 30 ng of template dna , whereas the amount was reduced by ˜ 40 % for 150 ng of template dna at 60 kj m - 2 . the average lesion frequency induced by the solar uvb simulator in the 500 -, 1080 -, and 2240 - bp segments per strand was plotted as a function of dose for four different amounts of dna ( fig3 a - c , respectively ) . the average lesion frequency increases linearly with increasing dose . however , the slope with the smaller amount of dried dna was greater than that with the larger amount of dna , showing that the average lesion frequencies decrease as the amount of dna increases per dose ( table 2 ). the effect of the initial amount of dna on the lesion frequency was further investigated by plotting the inverse of the slopes of fig3 a - c , shown in fig4 . the slopes in fig4 in kj m - 2 , represent the incident doses to induce one lesion in a 500 -, 1080 -, or 2240 - bp segment for each amount of dna . this result indicates that this quantity increases linearly as a function of the initial amount of template dna in the range studied . the lesion frequency in the 500 - bp segment with dried dna was compared with that for aqueous dna , both of which were irradiated with the solar uvb simulator . in fig5 is plotted the average lesion frequency for dried dna (), aqueous dna (♦), and dried dna covered with mylar film (▴) irradiated as a function of incident dose applied with the solar uvb simulator . the amount of dried dna was 30 ng at 16 pcr cycles . the concentration of aqueous dna was 5 ng μl - 1 . the inset indicates an average lesion frequency for aqueous dna solution irradiated with a germicidal lamp (□). the slope ( absorption cross section ) for dried dna is corrected by multiplying by a factor of 0 . 94 to correct for shielding (- - -). that for aqueous dna is corrected by multiplying by a factor of 0 . 6 (-- - --) . the concentration of aqueous dna was 5 ng μl - 1 and the amount to dna analyzed by pcr was 30 ng , as was the dried dna . table 2__________________________________________________________________________summary of standard dosimetry curves for 500 bp , 1080 bpand 2240 bp with four different amounts of dried λ dnanumber of absorption cross - dose / one lesionsamountlesions * section ( m . sup . 2 kj . sup .- 1 ) ( kj m . sup .- 2 ) of λdna500bp * 1080bp ** 2240bp *** 500bp # 1080bp + 2240bp § 500bp # 1080bp + 2240bp § __________________________________________________________________________25 ng1 . 33 1 . 90 3 . 30 2 . 20 × 10 . sup .- 2 4 . 9 × 10 . sup .- 2 16 . 5 × 10 . sup .- 2 45 . 0 20 . 4 6 . 150 ng1 . 00 1 . 39 2 . 37 1 . 67 × 10 . sup .- 2 3 . 5 × 10 . sup .- 2 11 . 9 × 10 . sup .- 2 60 . 0 28 . 8 8 . 4100 ng0 . 70 1 . 05 1 . 80 1 . 20 × 10 . sup .- 2 2 . 6 × 10 . sup .- 2 9 . 0 × 10 . sup .- 2 83 . 3 38 . 1 11 . 1150 ng0 . 50 0 . 82 1 . 40 0 . 88 × 10 . sup .- 2 2 . 1 × 10 . sup .- 2 7 . 0 × 10 . sup .- 2 114 . 0 48 . 8 14 . 3__________________________________________________________________________ * the average number of lesions at 60 kj m . sup .- 2 . ** the average number of lesions at 40 kj m . sup .- 2 . *** the average number of lesions at 20 kj m . sup .- 2 . # from fig3 a . + from fig3 b . § from fig3 c . this indicates that all the lesions that block the polymerase from synthesizing a new strand in a target segment were about twice as frequent in dried dna as in the aqueous dna , assuming that the doses absorbed by dna through dried and aqueous dna are the same . the effect of the germicidal lamp has been compared with that of the solar uvb simulator in producing the uv - induced lesions . the solar uvb simulator was about 200 times less effective in producing lesions than the germicidal lamp ( fig5 ). uv irradiation at 315 nm is known to be about 10 4 times less effective in producing the dna damage and killing e . coli than at 254 nm . the average lesion frequency induced by uv above 315 nm was investigated by filtering out the uv radiation below 315 nm using a layer of mylar film . the amount of amplified product in irradiated dna for 60 kj m - 2 was the same as that in unirradiated dna . thus the average lesion frequency per 500 - bp strand was nil at 60 kj m - 2 , as shown in fig5 . any photoinduced damage in dna induced by uva ( 320 - 400 nm ) apparently does not affect the amplification of the 500 - bp segment in the doses tested . thus the dosimeter of the present invention appears to truly represent a uvb dosimeter . the uv dosimeters encased in their housings were placed outdoors for 4 continuous days . the first set ( two dosimeters , a and b , each containing 50 ng of λ dna ) was placed outdoors in the fall in melbourne , fla . ( table 3 ). during this time interval there was sunlight with some patches of clouds each day , but there was rain in the evening ( 17 : 30 - 19 : 00 ) on the second day ( t high = 35 ° c ., t low = 20 ° c .). the total 4 - day day - dose was 39 . 5 - 41 . 6 kj m - 2 , with the average daily dose of 9 . 9 - 10 . 4 kj m - 2 . the second set ( two dosimeters , each containing 50 ng λ dna , a and b ; and two dosimeters , each containing 150 ng λ dna , c and d ) was placed in the same location as the first set , over four days in the winter . the weather at that time was clear and sunny ( t high = 10 ° c ., t low = 0 ° c . ), but it rained in the morning and became cloudy in the afternoon of the fourth day . the total 4 - day dose for that period was 19 . 9 - 22 . 2 kj m - 2 , with the average daily dose of 5 . 0 - 5 . 5 kj m - 2 with the 50 - ng dosimeter . the total 4 - day dose for that period was 20 . 4 - 21 . 3 kj m - 2 , with the average daily dose of 5 . 1 - 5 . 3 kj m - 2 with the 150 - ng dosimeter . both dosimeters recorded essentially the same dose , although the lesion frequencies were very different ( table 3 and fig6 ). thus the average daily dose was found to be ˜ 10 . 2 ± 0 . 4 kj m - 2 for the fall test and ˜ 5 . 2 ± 0 . 3 kj m - 2 for the winter test . table 3______________________________________summary of four - day dosimetryex - type of number of total 4 - day average dailyposed * dosimeter lesions ** dose ( kj m . sup .- 2 ) dose ( kj m . sup .- 2 ) ______________________________________fall a . ( 50 ng ) 0 . 694 ± 0 . 015 41 . 6 ± 0 . 9 10 . 4 ± 0 . 2 b . ( 50 ng ) 0 . 659 ± 0 . 041 39 . 5 ± 2 . 5 9 . 9 ± 0 . 6 a . ( 50 ng ) 0 . 369 ± 0 . 007 22 . 2 ± 0 . 4 5 . 5 ± 0 . 1 b . ( 50 ng ) 0 . 332 ± 0 . 014 19 . 9 ± 0 . 8 5 . 0 ± 0 . 2 c . ( 150 ng ) 0 . 179 ± 0 . 015 20 . 4 ± 1 . 8 5 . 1 ± 0 . 4 d . ( 150 ng ) 0 . 186 ± 0 . 018 21 . 3 ± 2 . 1 5 . 3 ± 0 . 5______________________________________ * started and ended at 5 pm of the day . ** the average lesion frequency per 500 bp per strand . a and b dosimeters for the fall and the winter tests , both of which contained 50 ng of dna , were prepared from the same dna solutions and dried at the same time . the amount of amplified product for the control used in the fall and winter was 0 . 72 ± 0 . 002 and 0 . 78 ± 0 . 04 mg , respectively , after 16 cycles . a year - old dosimeter also produced the same amount of the amplified segment within experimental error ( 0 . 77 ± 0 . 04 mg ). considering the different batches of pcr reagents used on two different assays , these numbers are well within experimental error , indicating the stability of the dosimeter of the present invention over at least a one - year shelf time . two different dosimeters were also positioned for time spans of 1 , 2 , and 4 days , one having 50 ng and the other having 100 ng λ dna per spot . the pcr analysis was then carried out with 2240 bp for the 1 - day exposure , 1080 bp for the 2 - day exposure , and 500 bp for the 4 - day exposure , the results of which are given in table 4 . the 4 - day doses of uvb based on the 1080 - and 2240 - bp amplification were within experimental error and agreed with the total 4 - day dose obtained with the 500 - bp amplification . it is believed that the principal mechanism of the pcr with irradiated dna is that photoinduced lesions block the new synthesis of amplified segments . the average lesion frequency per strand for each amount of initial template dna increases approximately linearly with increasing dose and decreases with the amount of initial template dna applied to the film . the surface area of spots is ˜ 5 × 10 - 6 m 2 and is independent of the initial amount of template dna applied . the only difference among these dosimeters is the concentration of solution before being dried ; therefore , the important parameter appears to be the number of molecules present after being dried ( table 2 ). in dried dna , the dna molecules stack upon each other as the amount the dna increases , which causes a shielding of the molecules below the top few layers ; therefore , the probability of a molecule below the top few layers interacting with a photon is very small . the average lesion frequency with a 150 - ng dosimeter was approximately half that with a 25 - ng dosimeter per dose , since the undamaged molecules protected by the top molecules contributed more to the formation of amplified segment . this effect is also plotted in fig7 a and 7b , wherein the average lesion frequency for 500 -, 1080 -, and 2240 - bp segments is plotted against dose for ( fig7 a ) 50 ng and ( fig7 b ) 100 ng of template dna . table 4__________________________________________________________________________summary of four - day dosimetry50 ng λdna 100 ng λdna total dose dose / day total dose dose / daydatesaverage lesions * ( kj m . sup .- 2 ) ( kj m . sup .- 2 ) average lesions * ( kj m . sup .- 2 ) ( kj m . sup .- 2 ) __________________________________________________________________________a . 2240 bp amplification for one - day dosimetryday 1 - 20 . 629 ± 0 . 072 5 . 3 ± 0 . 6 5 . 3 0 . 513 ± 0 . 071 5 . 5 ± 0 . 9 5 . 5day 2 - 30 . 577 ± 0 . 082 5 . 0 ± 0 . 6 5 . 0 0 . 536 ± 0 . 065 6 . 0 ± 0 . 7 6 . 0day 3 - 40 . 636 ± 0 . 017 5 . 4 ± 0 . 1 5 . 4 0 . 483 ± 0 . 066 5 . 4 ± 0 . 7 5 . 4day 4 - 50 . 435 ± 0 . 025 3 . 7 ± 0 . 2 3 . 7 0 . 343 ± 0 . 022 3 . 8 ± 0 . 3 3 . 8b . 1080 bp amplification for two - day dosimetryday 1 - 30 . 374 ± 0 . 075 10 . 8 ± 2 . 2 5 . 4 0 . 282 ± 0 . 035 10 . 8 ± 1 . 3 5 . 4day 3 - 50 . 309 ± 0 . 049 8 . 9 ± 1 . 4 4 . 5 0 . 262 ± 0 . 027 10 . 0 ± 1 . 0 5 . 0c . 500 bp amplification for four - day dosimetryday 1 - 50 . 350 ± 0 . 02 21 . 0 ± 1 . 4 5 . 3 0 . 254 ± 0 . 04 20 . 9 ± 3 . 3 5 . 2__________________________________________________________________________ * average number of lesions per 2240 bp , 1080 bp , and 500 bp per strand fo a , b , and c , respectively . a calculation of an amount of dna at which shielding begins has been performed . since this dna is ˜ 200 nm long and ˜ 50 nm wide ( icosahedral head plus tail ), a single molecule takes up ˜ 0 . 01 μm 2 . this implies that there are ˜ 100 molecules in a 1 μm 2 area . thus there are ˜ 5 × 10 8 molecules of dna , corresponding to an amount of ˜ 25 ng in a spot of 5 × 10 - 6 m 2 . by extrapolating the slope of fig4 at 25 ng , the average lesion frequency was found to be ˜ 1 . 33 . this is believed to represent the maximum number of lesions obtainable for the 500 - bp segment with a dose of 60 kj m - 2 . it is known that a percent survival of organisms subjected to radiation depends upon the material irradiated and the thickness of the material . a correction factor was found based upon the standard single - hit target theory . by multiplying the light intensities incident upon the surface by a correction factor , one can calculate the dose necessary to find the same inactivation if the organism were spread in a single layer on a surface . the correction factor for the efficiency of amplification of the specific segment of dried λ dna was found using the same analogy ( table 2 ). correction factors for the average dose through dried dna were found to be ˜ 0 . 94 , 0 . 76 , 0 . 55 , and 0 . 40 for 30 , 50 , 100 , and 150 ng dna for amplification of the 150 - ng segment , respectively . dried dna on a film such as that disclosed herein is easier to control than aqueous dna , although both in principle are usable as uvb dosimeters . an advantage of the dna dosimeter of the present invention comprises an inherent dynamic versatility for short - and long - term measurements . some biological dosimeters that are known in the art are so sensitive that they can be used for only a 1 - min exposure , or are so insensitive that they can be used for a month . an important feature of the present invention is the use of a nucleic acid molecule , in the preferred embodiment λ dna , the entire sequence of which is known . certain portions of the dna of different sizes can be created by choosing specific primers , which in turn provides a dosimetry for different exposure times . by also factoring in an initial amount of template dna present in each spot , a virtually continuous range of dosimeters can be constructed and analyzed . as an example , the three segment sizes discussed herein ( 500 , 1080 , and 2240 bp ) in combination with four different amounts of dna ( e . g ., 25 , 50 , 100 , and 150 ng ), provides twelve different dosimeters , from which it can be seen that a dosimeter could be tailored for specific exposure times . that is , a shorter - base - pair product would be preferable for longer exposure times , as the slope in fig2 is shallower ; and conversely for longer - base - pair products . exemplary base - pair products for desired exposure times are listed in table 5 . table 5______________________________________exposure time ranges for various sizes of base - pair productsbase - pair product size ( bp ) exposure time______________________________________ 230 2 weeks - 1 month 500 4 days - 2 weeks1080 2 - 8 days2240 1 - 4 days4000 1 - 6 hours______________________________________ the dosimeter and method of the present invention are seen to accomplish the stated goals of providing an inexpensive , small , portable device suitable for personal use . the device can be constructed so as to be impervious to extremes of environmental conditions and to be usable underwater . additionally , the invention provides an accurate measure of radiation dosage within a specific , predetermined wavelength range that has a builtin control sample and can be used for a wide range of times ( typically over a number of days , although this is not meant to be limiting ). as the dosimeter is biomolecular , only biologically effective doses are measured , which are considered valuable under a wide array of conditions . it may be appreciated by one skilled in the art that additional embodiments may be contemplated , including other dosimeter structures for alternative applications and the use of analogous biological macromolecules as radiation dosimeters for other ranges of incident wavelengths . in the foregoing description , certain terms have been used for brevity , clarity , and understanding , but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art , because such words are used for description purposes herein and are intended to be broadly construed . moreover , the embodiments of the device and method illustrated and described herein are by way of example , and the scope of the invention is not limited to the exact details of construction and analysis . having now described the invention , the construction , the operation and use of preferred embodiment thereof , and the advantageous new and useful results obtained thereby , the new and useful constructions , and reasonable mechanical equivalents thereof obvious to those skilled in the art , are set forth in the appended claims . __________________________________________________________________________sequence listing & lt ; 160 & gt ; 10 & lt ; 210 & gt ; 1 & lt ; 211 & gt ; 26 & lt ; 212 & gt ; dna & lt ; 213 & gt ; artificial sequence & lt ; 220 & gt ;& lt ; 223 & gt ; description of artificial sequence : 230 bp ( 7401 - 7630 ) primer 2 & lt ; 400 & gt ; 1ggttatcgaaatcagccacagcgcct26 & lt ; 210 & gt ; 2 & lt ; 211 & gt ; 25 & lt ; 212 & gt ; dna & lt ; 213 & gt ; artificial sequence & lt ; 220 & gt ;& lt ; 223 & gt ; description of artificial sequence : 230 bp ( 7401 - 7630 ) primer 0 & lt ; 400 & gt ; 2tgggatcagcgcagccggataccgt25 & lt ; 210 & gt ; 3 & lt ; 211 & gt ; 25 & lt ; 212 & gt ; dna & lt ; 213 & gt ; artificial sequence & lt ; 220 & gt ;& lt ; 223 & gt ; description of artificial sequence : 500 bp ( 7131 - 7630 ) primer 2 & lt ; 400 & gt ; 3ggttatcgaaatcagccacagcgcc25 & lt ; 210 & gt ; 4 & lt ; 211 & gt ; 25 & lt ; 212 & gt ; dna & lt ; 213 & gt ; artificial sequence & lt ; 220 & gt ;& lt ; 223 & gt ; description of artificial sequence : 500 bp ( 7131 - 7630 ) primer 1 & lt ; 400 & gt ; 4gatgagttcgtgtccgtacaactgg25 & lt ; 210 & gt ; 5 & lt ; 211 & gt ; 25 & lt ; 212 & gt ; dna & lt ; 213 & gt ; artificial sequence & lt ; 220 & gt ;& lt ; 223 & gt ; description of artificial sequence : 1080 bp ( 6551 - 7630 ) primer 2 & lt ; 400 & gt ; 5ggttatcgaaatcagccacagcgcc25 & lt ; 210 & gt ; 6 & lt ; 211 & gt ; 25 & lt ; 212 & gt ; dna & lt ; 213 & gt ; artificial sequence & lt ; 220 & gt ;& lt ; 223 & gt ; description of artificial sequence : 1080 bp ( 6551 - 7630 ) primer 4 & lt ; 400 & gt ; 6atacaccatgaccggtgaagccttc25 & lt ; 210 & gt ; 7 & lt ; 211 & gt ; 25 & lt ; 212 & gt ; dna & lt ; 213 & gt ; artificial sequence & lt ; 220 & gt ;& lt ; 223 & gt ; description of artificial sequence : 2240 bp ( 5391 - 7630 ) primer 2 & lt ; 400 & gt ; 7ggttatcgaaatcagccacagcgcc25 & lt ; 210 & gt ; 8 & lt ; 211 & gt ; 25 & lt ; 212 & gt ; dna & lt ; 213 & gt ; artificial sequence & lt ; 220 & gt ;& lt ; 223 & gt ; description of artificial sequence : 2240 bp ( 5391 - 7630 ) primer 3 & lt ; 400 & gt ; 8ctgacgttactgacgtggtgccagc25 & lt ; 210 & gt ; 9 & lt ; 211 & gt ; 26 & lt ; 212 & gt ; dna & lt ; 213 & gt ; artificial sequence & lt ; 220 & gt ;& lt ; 223 & gt ; description of artificial sequence : 4000 bp ( 3631 - 7630 ) primer 2 & lt ; 400 & gt ; 9ggttatcgaaatcagccacagcgcct26 & lt ; 210 & gt ; 10 & lt ; 211 & gt ; 25 & lt ; 212 & gt ; dna & lt ; 213 & gt ; artificial sequence & lt ; 220 & gt ;& lt ; 223 & gt ; description of artificial sequence : 4000 bp ( 3631 - 7630 ) primer 5 & lt ; 400 & gt ; 10aacacgcagctgcagagcgccattg25__________________________________________________________________________