Failure Knowledge Database / 100 Selected Cases

Contamination of rice bran oil with PCB used as the heating
medium by leakage through penetration holes
at the heating coil tube in deodorization chamber
Feb. 1968, Kitakyushu, Fukuoka-pref.
SUZUKI, Tsuguo (Former Ajinomoto Co., Inc.)KOBAYASHI, Hideo (Tokyo Institute of Technology)(Summary)
From February to March, 1968, a mysterious sickness causing difficulty in breathing occurred in poultry
farms in a w ide area of western Japan, resulting in the death of o ver 400 t housand birds. These chickens
had been fe d the d ark o il p roduced a t K anemi Co, m ainly composed of fa tty a cids, w hich is one of t hebyproducts of the deodorization process in the rice bran oil refining processes. From June to August, 1968,
effects on human began to appear successively in western Japan as symptoms of skin rash and the internalorgan diseases. These effects were generically called "Yusho". In October, 1968, one of the patients gave asample to the local government health center of the rice bran oil made by Kanemi Co. that the patient had
been us ing a t th at time. Fro m the res ults of researc hes and i nvestigations by sci entists at t he f aculty ofmedicine, K yushu U niversity, a nd a t the de partment of h ealth, Fu kuoka Prefect ure, the cause of t hediseases was determined to be the rice oil that was found to be contaminated with PCB. When an abnormal
decrease in amount of the circulating PCB occurred in the deodorization process of the K anemi Co., fromthe end of January to t he beginning of February, 1968, the operation staff replenished the PCB d esultorily
without investigating the reason. This action resulted in the contamination of th e rice oi l product with asmuch as 280 kg of PCB. To make matters worth, even after the facts were clarified, they did not dispose thethree dr ums o f co ntaminated re covered oil but ins tead reuse d it by mixing t he c ontaminated oil t o t henormal product after only by re-deodorizing the mixture. The re corded number of pat ients rea ched t o 14
thousands. The ac tual reason for the heath diseases has recently been postulated to be the dioxins that are
produced through the deterioration of the PCB, rather than PCB itself.
1. EventThe leakage occurred thr ough two routes that happened at the almost same ti me. One was a pin-holethat had been formed by inter-granular corrosion. The other was a hole that had been made accidentally bya mistake during a welding operation.
[ Route 1: the pin-hole formed by corrosion ]In th e N o.6 c hamber out o f a tot al of si x ch ambers,inter-granular corrosion occurred atthe hea taffected zone of the seam w eld line on the h eating c oil m ade of T ype 3 16 sta inless w eld tube (4 0mmdiameter, 2 mm thickn ess), w hich c aused a pi n-hole to o pen. The pi n-hole h ad be en p lugged by apolymerized oil product until the time of the leakage, but a shock during the repair works made an open pit.
The heating coil tubes in the other five chambers, which had been used for a l onger period, were made of1

Failure Knowledge Database / 100 Selected Cases

Type 316L stainless weld tube. Therefore, inter-granular corrosion did not occur in the other heating coiltubes.
[ Route 2: the hole formed by welding mistake ]In the No.1 chamber, a welding worker made an open hole in the adjacent heating coil tube by a mistake
during welding, during a small welding operation for a sheath pipe of a thermometer.
2. Course
In the fac tory, the deodorizing pro cess was con ducted by usin g si x vac uum cham bers in a bat chconfiguration (Figure 1). This configuration is different from the co ntinuous l ongitudinal multi-tray
vacuum column that is usually used at most large scale edible oil producing factories.
[ Route 1 ]The seam welded tube used for the No. 6 deodorization chamber was made of a hi gh carbon containing
Type 3 16 st ainless stee l. Solution h eat treatm ent ha d eit her b een insuf ficient, e.g. under t oo l ow atemperature, or not provided at all in the tubing process at the steel maker's shop. Therefore, the sensitizedzone a long t he we ld li ne suf fered from the i nter-granular c orrosion ca used by th e c ombination ofhydrochloric acid form ed by dec omposition of PCB with acoexisting tr ace amount of wa ter. Theinter-granular corrosion, which propagated after fi ve or more y ears of opera tion, formed defects and pits
along the grain boundary. The pits had been plugged by some polymerized oil until the time of the leakage,
but a sh ock during t he re pair w ork an d re-i nstallation co nducted o n J anuary 1, 1968, caused to breakthrough t he open p it. The lea kage of PCB oc curred t hrough t he p its af ter re-startin g operation,
contaminating the edible oil.
[ Route 2 ]On Ja nuary 29, 1968, one of t he m aintenance w orkers of K anemi Co., c onducted a sm all w elding
operation to expand a hole at the top of a thermometer sheath in the No.1 deodorization chamber. At thattime, the w orker m ade a n open hole at t he adjacent heating c oil tube by a m istake during the w elding.
Through the hole, a large amount of PCB leaked into the part of the facility that contained the edible oil,causing the contamination. The amount of leakage of PCB via route 2 was estimated to be much larger thanthat via route 1.
However, eve n after the le akage and contamination was foun d, th e m anagers i n t he fa ctory did n ot
recognize t he seri ousness of t he pr oblem, so t hey did not isolate or a bandon t he c ontaminated oil, butinstead they sold it to consumers.
In legalistic standpoint, the main cause of the contamination was determined by judicial decision to be
the leakage via route 2, because the amount of PCB leakage was larger than that via route 1.
3. CauseRoute 1: Pin-hole formed by inter-granular corrosion in a high carbon containing stainless steel tube.
Route 2: A hole created by a mistake during a welding operation.

2

Failure Knowledge Database / 100 Selected Cases

4. Countermeasure(1) Dangerous su bstances m ust not b e use d in foo d pro cesses even as m aterials on ly inindirectly

contact w ith food pr oducts, su ch as h eat transfer fl uids. At t hat tim e, n on-chlorine c ontaining
chemicals such as diphenyl or diphenyl ether (e.g. Dowtherm, etc.) were adopted as the heating fluids
in various plants manufacturing edible oil. Recently, high temperature w ater or pressurized steam ismainly used as the heating fluid for food processes.
(2) In the construction of food refining plants construction, the equipment materials must be exhaustively
checked and confirmed in ord er t o a void i ntroduction of ina ppropriate materials, e.g . Type 316
stainless steel in place of Type 316L. Measures to increase corrosion resistance and reliability must be
considered, for example adopting seamless tubes in stead of weld tubes.
(3) In the construction of new plants or the repair of existing equipments, supervision of ac tivities in thefield must be strictly enforced and skilled workers should be employed.
(4) Above all, maintenance of c omplete quality control and observation of good manufacturing practicemust take highest priority in manufacturing foods for human consumption.
5. Knowledge
In manufacturing foods for human consumption, the following items should be noted;(1) When new chemicals, substances, or materials are introduced to the processes, safety for human healthmust be e valuated an d co nfirmed, reg ardless of w hether th e s ubstances are i ndirect or in directcontact with the food products. Unconfirmed materials must never be introduced to the processes.
(2) Leakage in heat e xchangers will h appen sooner or la ter. Therefore, the fo llowing measures must be
conducted comprehensively selec t saf e heat tr ansfer fluids, se lect highly res istant m aterials for t heequipment, strictly enforce supervision of construction and repairing field work, and keep equipment
completely maintained.
(3) Foods are t aken by the mouth into human bodies freely without the control of medical doctors. Thequality of fo ods, th erefore, m ust be c ontrolled a nd guaranteed e ven m ore rigo rously t han t hat ofmedicines.
6. Background
PCB is a colorless, oily liquid, with superior electric insulation property and thermal stability. PCB isused as an insulator for high-voltage transformers, condensers, and stabilizers for fluorescent lamp. PCB isalso used as an additive for paints, a heat transfer fluid, and so on. However PCB is thought to have effects
as an endocrine disruptor, in addition to causing direct health effects such as skin rush. In Japan, PCB wasnoted for its toxicity with the Kanemi Yusho incident in 1968, as a turning point. In 1972, the use of PCB in
open systems was prohibited, and in 1974, the manufacture and the use of PCB were banned completely.
The recovery of PCB from users has been conducted in earnest, but there is still a large amount of PCB inuse, particularly in closed systems.
Manufacture of PCB was started in 1929 at Swan Co., USA. Immediately after that, the toxicity of PCB
began to c ause problems such as the chlorine pimple disease in laborers, which was confirmed by anim al3

Failure Knowledge Database / 100 Selected Cases

experiments. However, because of the excellent properties of PCB, the production was expanded especiallyfor military uses and we apon industries. The production of PCB i n Japan was start ed in 1954. Soon after
that, the pollution pr oblems fro m PCB were fou nd a ll over t he w orld, such as cont aminated fee d forchickens in USA and environmental co ntamination i n Sw eden. T he K anemi Y usho i ncident i n Ja pan
happened in 1968.
7. Sequel
Taking this PCB problem as an opportunity, in 1973 the Law Concerning the Evaluation of Chemical
Substances and Regulation of the ir Manufacture, etc. (Chemical Substances Control Law) was enac ted inJapan. The L aw requir es prior evaluat ion of c ertain hazardous pr operties of new chem ical substances
before manufacturing a nd/or im porting those su bstances. T he Law reg ulates (1) persis tent and h ighlybioaccumulative chem ical substa nces with lo ng-term toxicity o r ec otoxiticy (Spec ified ChemicalSubstances), (2)persistent but no t bi oaccumulative chem ical subst ances wi th certain ec otoxiticy(Monitored C hemical Substances), and (3) New C hemical Substa nces. R ecently, t he Law i ntroduced
regulations fo r ev aluation not o nly of d amage t o human health by environmental p ollution, b ut a lso ofdamage to flora and fauna.
8. Discussion
The patients of "Yusho" had been recognized based only on the evaluated PCB concentrations that havepersisted in t heir bodies. However, r ecently t he concentration of dioxin w as a dded to t he b ase (2 004),
because high concentrations of PCD F (poly-chlorinated di-benzofurane), a kind of dioxins that is formedby the thermal decomposition of PCB, were detected in their blood.
Another w ell-known case of food co ntamination i n Japa n w as the contamination of pow der m ilk forbabies with arsenic by Morinaga Co. The relief measures by Morinaga were more generous than those ofKanemi, in part because of the larger size of the Morinaga enterprise.
9. Information Source(1) Y. Tokunaga; Netsushori, vol.19, No.4 (frontispiece) (1979).
(2) T. Sugimoto;"Considering PL in Japan", p.48, Chijin-shokan (2000).
(3) H. Kawana; "Verification of Kanemi Yusho incident", Ryokufu-shuppan (2005).
(4) h ttp:www.safe.go.jp/kasin.html.
(5) Asahi-shinbun, Morning Ed., December 18 (2003).
10. Primary Scenario(1) Route 1 (pin-hole by corrosion)
01. Misjudgment
02. Narrow Outlook
03. Oversight of Intermixing Wrong Material (Type 316 stainless steel)4

Failure Knowledge Database / 100 Selected Cases

04. Lacked Research in Corrosivity of PCB
05. Production
06. Hardware Production
07. Production of Machine/Equipment
08. Heating Coil for Deodorant Column
09. High-C Stainless Steel (Type 316)
10. Lacked Inspection in Receiving Materials
11. Purchase of Sensitized Material
12. Failure
13. Fracture/Damage
14. Intergranular Corrosion
15. Contamination of PCB to Food Product16. Bodily Harm
17. Sickness
18. Poisoning(2) Route 2 (hole by welding miss)
01. Carelessness
02. Insufficient Precaution
03. Lacked Precaution in Worker
0 4. Welding Work
05. Usage
06. Maintenance/Repair
07. Make Hole by Welding to Adjacent Part
08. Failure
09. Fracture/Damage
10. Heating Coil for Deodorant Column
11. Make Hole by Welding
12. Lacked Inspection in Finishing Work
13. Contamination of PCB to Food Product14. Bodily Harm
15. Sickness
16. Poisoning

5

Failure Knowledge Database / 100 Selected Cases

Vacuum s ource

Rice bran oil

BaffleLooking glass
Coil
Insulator
PCB
PCB
Steam

Rice bran oil

Mist of rice bran oil
Fig. 1

Schematic diagram of deodorant vessel.

6