CAPÍTULO 2: MARCO TEÓRICO
2.3 SISTEMAS DE GESTIÓN AMBIENTAL Y SISTEMAS DE GESTIÓN DE
2.3.8 ANÁLISIS Y RELACIÓN ENTRE LA NORMA ISO 14001 Y OHSAS
Figure 4.10 shows the average death rate in each age group. Only infant mortality from choking on food is high. All other age groups have a low average death rate.
o 12
u n d e r 1 1-4 y e a r s 5 -1 4 y e a r 1 5 - 4 9 y e a r s A g e g r o u p
a m a le p e r 1 0 0 0 0 0 □ f e m a le p e r 1 0 0 0 0 0
5 0 +
Figure 4.10 The average age sp ecific death rates for those choking on Food (1894-1993).
Se x R at io s
The average sex ratio for each age group shows that more males than females die from choking on food (Fig. 4.11). However, for all age groups there are times when more females die than males. Ratios below one indicate a higher number o f female deaths than male deaths. The range o f sex ratios for choking on food is narrow. All age groups range from no male deaths, that is a ratio o f zero to a maximum o f 5:1 male/female deaths, in the over 50 year olds. In only a few years do the sex ratios exceed the range; in no group does the sex ratio exceed the range more than five times. Table 4.4 shows the range o f variation in the sex ratios for choking to death on food.
Table 4.4 The sex ratios for choking to death on food for each age group RANGE Ag e c o u p U n d e r I y e a r 1-4 YEARS 5 -1 4 YEARS 1 5-49 YEARS 50 TE4Æ&' 0-2 0-4 0-4 0-4 0-5 Ou t l i e r s 2 ,4 5 ,9 5 .8 5 .9 6 , 7 , 1 3 157
o
I -<
cr X LU œ 1 4i 12- 10' 8- 6- 4 - 2 i 0. -2. N= i * o * t0
o o 100 100 100 100 100 u n d e r l y r 1 -4 y rs 5 -1 4 y rs 1 5 -4 9 y rs 5 0 y rs+ AGE GROUPFigure 4.11 The sex ratio o f choking to death on food by agegroup for the 100 years from 1894-1993
D
is c u s s io nIf the hypothesis that a low larynx confers a functional disadvantage on modem humans were correct then one would expect that deaths from choking on food would be high. Comparisons o f choking death rates with those for cancer and infectious diseases show that the death rate for choking on food has been low for the whole period
investigated in this study (Fig. 4.1). The total death rate in the population o f England and Wales has been approximately 1,200 per 100,000 for most o f the 20^ century (Fig. 4.2). In contrast, death rates for choking on food average 0.6 per 100,000 across the entire group.
One would also expect to see an increase in the death rate from choking on food at the ages when the larynx was descending. In children the first descent o f the larynx occurs at about two years old (Westhorpe, 1987; Maguipes & Laitman, 1986). There is also a further descent particularly in boys at puberty. Furthermore, one would expect to see the death rate remain high in adults, particularly men who have a very low laryngeal position. However, the data do not support these assumptions. The lowest death rates from choking on food occur in those groups where a high rate would be expected. Children and younger teenagers seem remarkably adept at coping with the sudden changes occurring in laryngeal position. Not only are their deaths from choking on food at a low level but they do not seem to follow the secular increase evident in other age groups. Numbers o f deaths from choking on food in very young children have remained constant both in this study and in other studies that have looked at all causes o f child mortality, (for example, Byand et al.
1996). There is little variation in either the number or rate o f deaths in young children.
Deaths from choking on food are low in prime aged adults during the whole period investigated in this study. There is a comparative increase during the 1950’s although it never rises above one per 100,000 in either sex. Incidence o f choking on food in the USA also shows the same rate as in England and Wales (Mittleman et a l 1982). The number o f deaths, around 3,000 a year in the USA, is more often quoted (Kitty et a l 1987). This seems a large number o f deaths, but is proportionately small.
Most adult deaths from choking on food are related to the consumption o f alcohol (Ekberg & Feinberg, 1992; Maul, 1982; Mittleman & Welti, 1982). Men tend to drink more heavily and more regularly than women do and this contributes to the widening in
death rates between the sexes (Johnson & Hoskins, 1991). In this study, the average male to female ratio o f death is 3:1. This is similar to the rates found in Germany : i the USA. The German study found a 3:1 ratio o f males to females in the fatal incidence they
investigated (Bonte & Jacob 1990). In the majority o f deaths, the victim was very drunk. In the USA the male to female ratio is about 2:1 (Baker 1980).
Psychiatric patients are the next largest group to choke to death on food after drunken adult men (Hsieh, Bhatia, Anderson and Cheng 1986; Fioritti et al. 1997). This group probably accounts for the rise in adult deaths after 1950. During the 1950’s, new drugs have been introduced to treat psychiatric illnesses. Many o f these drugs, for example Chlorpromazine, have known side effects which affect muscle co-ordination (Strange,
1992). The loss o f muscle co-ordination from the drug regime implemented in hospital increases the risk from choking on food as swallowing co-ordination is affected. Furthermore, the type o f food offered to these patients may also increase the risk of choking. Much uSe is made o f snack foods such as crisps to encourage the patients to eat (Fioritti et a l 1997). The use o f this friable food together with the lack o f swallowing co ordination may increase the deathrate among psychiatric patients (Asieh et al. 1986).
Before 1950’s the elderly (here taken as the over 50’s) show very low numbers of deaths from choking on food. Similar factors to those for prime aged adults probably account for some o f the increase after 1950. The middle o f the 20th century has seen many changes in the life o f the elderly. Life expectancy increase means that there are many more elderly in the population. The likelihood o f surviving illness and disease that would have killed earlier populations has increased. However, it has meant that many individuals survive with reduced capabilities leaving them less equipped to deal with daily life including eating.
Increased survival has led to a rise in the number o f individuals in nursing and residential homes. The type and texture o f the food offered in such institutions is often different to that which the elderly person is used to, being softer and requiring less chewing. This can cause swallowing difficulties, which may lead to choking, particularly during the initial transition from home to institutional Hfe (Hogstel & Robinson 1989). More recently the numbers o f deaths from choking on food has begun to decline in the elderly as better information and feeding practices are introduced.
The most surprising finding from the data was the high level o f deaths from choking on food during the first year o f life. Infants comprise the major proportion o f all
deaths from choking on food (Fig 4.15). Infant deaths must be considered in two separate groups. The groups can be designated high mortality (1936-■ 979) and low mortality (1894-1935). During the low mortality years congenital abnormalities, such as cleft palate may be responsible for some deaths as oral and pharyngeal abnormalities are still
responsible for infant choking deaths today (Tawfik, Dickson, Clarke & Thomas, 1997). There is also some re-organisation in the movement o f vocal tract structures such as the soft palate occurring. These are respiratory changes that relate to the move from obligate nose breathing (Saski et a l 1977). These changes have been associated with prolonged apnoea and food (milk) inhalation (Steinschneider & Tabnzzi 1976). This change in respiration may be linked to sudden infant death syndrome (Grelin, 1987; Maguipes & Laitman, 1986). The change in respiratory pattern is regarded as a prerequisite for human speech (Laitman et a l 1977). If this is, so then perhaps it is not surprising that the rate is higher than expected in the low mortality years. Therefore during the period under
investigation congenital abnormalities and respiratory changes may explain the higher than expected death rate in these infants in whom the larynx is yet to descend. There is
however, some evidence that infants can easily breathe through their mouth if the nose is blocked, by raising the soft palate and expanding the nasopharynx (Rodenstein, Perknutter, & Stanescu, 1985). Babies do not suffocate if they have a cold.
However, the upward trend cannot wholly be explained by these factors. The increase in deaths occurred when surgery for abnormalities was being established and it is unlikely that there are major differences between the two groups in respiratory pattern. It seems more likely that environmental changes are responsible for the increase in the death rate from choking on food in the under 1 year olds. Four factors, which relate neither to the descent o f the larynx nor to the change in respiratory pattern directly, can be proposed as possible explanations o f the sudden increase in infant deaths from choking on food. These factors relate to either changes in the feeding method or changes in the consistency o f the food offered, or change in the type o f food given or finally additives within the food, which give an allergic response.
During the late 19‘^ century and early 20^ century, most infants were breast-fed (Fildes, 1986, 1992). Since the 1930’s there has been a decline in the percentage o f infants who are breastfed (Department o f Health, 1988). The increase in infant deaths also begins at about this time.
T 100 300 T -- 90 250 - -- 80 -- 70 m 2 0 0 -
I
Q O 150 -- S E =3 ^ 1 0 0 - - 60 - 50 OqO -- 40 - 30 - 20 50 - 10 1910 1930 1970 1990 1890 1950 Yearso female o maie % breastfed
F igu re 4 .1 2 C o m p a riso n o f th e d e c lin e in b r ea stfee d in g w ith th e nu m b er o f d e a th s from c h o k in g on food in u n der 1 year o ld s (1 8 9 4 - 1 9 9 3 ) .
The widespread introduction o f formulae feeding resulted in advice on infant feeding being given to mothers. Much o f the advice was from companies actually selling infant formulae rather than independent advice. Even today surveys o f doctors show that much o f the advice they give to new mothers comes from formula company literature (Howard et a l , 1997; Valaitis et a i , 1997). Current research in the developing world shows that breast-feeding is often at low levels (Chye et a l , 1997). A comparison o f death rates in the under one year olds would provide support for arguments made in this study. However, the data are not readily available. The comparatively low death rates compared to other causes o f infant mortality in many countries mean that choking on food as a cause o f death is not listed separately ft om other causes o f choking or sometimes even all accidental deaths.
The introduction o f formula milks, particularly after the founding o f the NHS, brought about infant feeding regimes. Rather than feeding when the baby was hungry, the infant is fed to a timetable, and this increases the likelihood that the infant will become hungry ‘between’ feeds (Linnenberg, Artola, & Estrada, 1990). In these peak mortality years only 9% o f infants are breastfed at six months old but 40% had cereal added to their diet at six weeks old (Department o f Health 1988). As extra milk feeds were discouraged.
supplementary foods was introduced at an early age. Unfortunately, the swallowing mechanism of babies has not yet matured enough to cope with solid foods. The infant is still adapted to a milk diet and still has some way to go before the adult swallow needed for solid foods is in place. The adult swallowing mechanism develops at approximately 1 year old (Stevenson & Allaire, 1991). This leads to a widening gap in feeding practices with bottle-fed infants receiving solid food much earlier than breast fed infants (Brogan & Fox 1984). Infants who are bottle-fed are also at risk from bottle propping. During this activity, the infant is left unattended to bottle-feed. This will probably increase the risk that a choking episode will be undetected until too late. In addition, parents who bottle-prop are more likely to add cereal to the milk, increasing the chance o f choking (Linnenberg et a l 1990).
Baby boys are more likely to be bottle-fed, and therefore to be introduced to soHd foods earlier than girls (Brogan & Fox 1984). Medical advice, even quite recently, on infant feeding recommends introducing solids to boys earlier than girls based on their larger size (Department o f Health 1988). This is particularly unfortunate as boys develop more slowly than girls do. This slower rate o f development in boys was recognised in much earlier advice to mothers which recommended longer breastfeeding as boys were ‘harder to rear’ (Fildes 1986). Therefore, we have encouraged earlier weaning in the infants least capable o f coping with solid foods. The sex difference in infant deaths from choking on food found in this study might reflect the impact that this differential feeding has on survival.
The form o f the foods also plays a part; the advice from health professionals was to give ‘finger’ food to older infants (Dept o f Health, 1988). This was supposed to get the infant ready for a full adult diet. However, they are mostly unable to chew and swallow this food and suck it instead. Large portions are thus likely to break off and lodge in the pharynx and larynx. From the 1950’s foods have become more processed and snack and fast foods play an increasing part in our diet. These foods are often fed to older infants, who although they have teeth are unable to chew and swallow in a fully adult manner. Documentation o f the types o f foods infants choke on show that snack and fast foods, particularly peanuts, become an increasing cause of death (Harris et a l, 1984; Baker & Fisher 1980). An increase in the number o f mothers breast-feeding has recently been observed and this has had an impact on the timing o f the introduction o f solid food (Wharton 1982). Furthermore, changes in advice on feeding given to mothers in recent
years, regarding snack foods and the introduction o f solids at an early age (Department of Health 1988), has probably caused deaths from choking on food to have fallen to and drop below those levels seen in the early part o f the 20^ century. There is, however, always a delay between medical advice changing and near universal adoption o f the changes. Many mothers still introduce solids earlier than the current recommendations (Skinner et a l
1997). The information on infant food packets still suggests the introduction o f solids at 3- 4 months old despite the advice o f the Department o f Health (Howard et a l 1997)
This trend o f a rise and then fall in infants choking on food has also been observed in other European countries. An analysis o f mortality data in Spain (ViUalbi et a l, 1992) has also shown an increase from 5.7 children per 100,000 in 1970 to 34.47 per 100,000 in
1977. The authors comment on the more recent decline in death rates. Similar factors are proposed for this increase as are proposed in this study (ViUalbi, 1992).
There is Uttle direct evidence for choking on food to be associated with food additives, dust mites, or environmental poUution. However, some food additives do cause breathing difficulties in young chUdren (Walker, 1999). Environmental poUution has been proposed as the cause o f a large increase in the number o f chUdren with asthma (Marzin, Le MouUec, AnceUe, Juhel, Festy & Pretet, 1993) as has dust mites (Duhme, WeUand & KeU, 1998). AU these factors could be impUcated in choking on food if they have altered the swaUowmg co-ordination in some way. The increase in adult deaths may be related to these two factors. The adult rate begins to increase at about the time when the chUdren bom at the time o f the first rise in infant deaths occurred would be reaching adulthood. It may be that increased sensitivity to aUergens or poUutants may have affected these individuals making them more susceptible to choking on food. More recently many
additives associated with aUergies have been removed from our food in Great Britain. This may be related to the return to lower mortaUty levels in the 1990’s.
There may be a future rise in death rates in young infants. Studies are beginning to show that mothers who are employed are more Ukely to bottle feed (Lindenberg et
a l 1990). Their chUdren are also more likely to be cared for by others who may have different ideas on chUdcare than the mother. The greater the participation o f women in the work force the more likely this becomes. Society needs to recognise the needs o f the infant and ensure that the mother has the time and the money with which to care for the chUd.
Co n c l u s i o n s
The results of this study offer no support for the hypothesis that a low laryngeal position confers a functional disadvantage on modem humans. Deaths from choking on food are rare. In England and Wales during the 100 years to 1993, the average death rate from choking on food was 0.6 per 100,000. No increase in deaths was seen at times o f laryngeal descent. The majority o f deaths from choking on food appear to be culturally mediated. They relate to changes in infant feeding practices and to the consumption o f alcohol.