Dubravka Topalović

UTICAJ OLOVA NA KONGNITVNI RAZVOJ

• Karakteristike:

• olovo (Pb) je sivkastoplavi mek metal• pripada IV grupi u PSE• u jedinjenjima je dvovalentan, cetvorovalentan i nestabilan• loš provodnik toplote i elektriciteta• na vazduhu oksidiše u olovo oksid

Izvori

• u prirodi retko se nalazi kao čisto.• najvažnije rude su galenit, cerusit i anglezit.• rudnici, livnice, štamparije i akulmulatorska industrija• kontanimirana hrana i voda, prisustvo u vazduhu, predmeti izrađeni od olova

Toksikokinetika

ounos inhalatorno i ingestijom

oapsorbcija je najveća na nivou ileuma

otransportuje se oko 95% vezano za eritrocite

oveći deo se taloži u kostima

oprolazi placentu i može se naći u plodu od 12. do 14. ned.

oeliminacija se odvija putem bubrega

Toksikodinamika

• gradi komplexe sa ligandima koji sadrže S, N i O kao donor elektrona.

• sa sulfihidrilnim grupama enzima gradi merkaptide.

• izraženo inhibitorno delovanje na enzime koji učestvuju u biosintezi hema.

Toksikodinamika 2• Neurotropno delovanje na PNS, CNS i ANS.

(encefalopatija,*dying back*)

• Nefrotoksični efekat ( hronična intersticijalana fibroza, vaskularne promene arterija)

• Hepatotoksični efekat

• Pojava olovnog ruba

Although no blood level of lead is considered safe, the Centers for Disease Control and Prevention (CDC) has established 10 µg/dL as the level of concern. Approximately 9% of children aged 1-5 years have blood levels higher than 10 µg/dL. Because low socioeconomic status is also a risk factor for lead exposure, children in inner cities are at highest risk. In some rural areas of the United States, 20% of children have been reported to have levels higher than 10 µg/dL. [13]

• Lead poisoning occurs in every group, and only the frequency varies; it is not just a disease of black inner-city children. According to the 1997 National Health and Nutrition Examination Survey (NHANES), 16.4% of children living in cities with more than 1 million people and in homes built before 1946 have elevated lead levels.

• Of interest is the remarkable decrease in the prevalence of elevated lead levels in children in the 1999-2004 time frame as compared with the 1988-1991 time frame. According to the NHANES data, the prevalence of children with lead levels over 10 µg/dL was 8.4% in 1988-1991 but only 1.4% in 1999-2004, representing an 84% decline.[14] levels continue to be highest among non-Hispanic black children, Mexican American, and non-Hispanic white children, with the greatest risk being in the non-Hispanic black population.

• Generally, adults develop lead poisoning as the result of an occupational exposure or from exposure through a hobby. Several states cooperate in the SENSOR program, which monitors lead exposure in adults from occupational sources.

• International statistics• Lead poisoning has been reported in almost every country

on earth. Blood lead levels are higher in developing countries because of continued use or later phaseout of leaded gasoline and paint. Occupational exposure in these countries is higher as well. In particular, the old “iron-curtain” countries had less strict guidelines for occupational and environmental exposures than other places in the world; thus, exposures there were common. • A Swedish study by Evans et al, which reported on 926

patients with incident severe CKD and 998 controls with a 7- to 9-year follow-up, suggested that low-level exposure to lead may not cause an increased risk of severe chronic kidney disease (CKD).[16] However, the authors cautioned that because only native Swedes were used in their study, the generalizability of the data may be limited; they also noted that whereas an expert rating method was used to assess lead exposure, BLLs were not measured to confirm the rating method’s validity.[16]

• Age-related demographics• Young children who are independently mobile are at greatest neurologic risk

from chronic exposure to low or moderate levels of lead. From the time children are able to crawl until they enter school, they are at risk of ingesting lead-containing dust. Although this sometimes is associated with pica and intentional ingestion of paint chips, lead poisoning often occurs without such behavior. Children may also be at risk for lead toxicity if folk remedies are used or if their parents, siblings, or caregivers are involved in lead-related occupations. • Children younger than 3 years are at the greatest risk for lead poisoning.

This is because these children are most likely to put things containing lead into their mouths and because their brains are rapidly developing and are most vulnerable to any disorganizing influence. However, physicians and other health care professionals must be aware that lead poisoning can occur in children of any age. • Adults are now believed to be affected at a lower level of exposure than was

once assumed. This has sparked renewed interest in occupational exposure to lead and its consequences. Careful attention must be paid to the occupations of adults who present with uncommon peculiar symptoms and signs.• Sex-related demographics• Because of occupational exposures, men have higher lead levels than

women. No sex difference in incidence is reported in children.

• Racial differences in incidence• Although no compelling evidence exists that any particular race is biologically

predisposed to lead toxicity, covariant conditions such as poor nutrition and lower socioeconomic status clearly are associated with chronic lead poisoning.

• Certain populations, such as African American children and new immigrants living in homes with decaying lead-based paint in low-income urban centers, are at increased risk of lead poisoning. The NHANES III data have shown higher lead levels among non-Hispanic blacks and Mexican Americans. Whether this translates into a higher incidence of lead nephropathy among these persons is not known.

• Overall, black non-Hispanic children appear to have the greatest risk of developing lead poisoning. The NHANES figures for 1997 reveal a prevalence rate of 21.9% among black non-Hispanic children living in homes built before 1946, a rate of 13.7% in those living in homes built in 1946-1973, and a rate of 3.4% in those living in homes built subsequent to 1973.

• This compares to a prevalence of 13%, 2.3%, and 1.6% among Mexican-American children and 5.6%, 1.4%, and 1.5% among white non-Hispanic children living in homes built before 1946, living in homes built in 1946-1973, and living in homes built subsequent to 1973, respectively.

• An analysis of trends in blood lead levels over the past 20 years shows that, although the overall geometric mean blood lead level in children has dropped dramatically, disparities still exist, causing increased risk to certain populations. The factors of living in older housing, poverty, age, and being non-Hispanic black places a child at risk for elevated blood lead levels. [14]

Prognosis

• In the pediatric population, fatalities associated with lead encephalopathy were reported in the 1960s. Today, with aggressive management of ICP, these deaths are preventable. Occasional cases of acute lead encephalopathy still occur, and these often result in severe neurologic damage. Mounting evidence suggests that lead poisoning in childhood produces a long-term problem with learning, intelligence, and earning power. Asymptomatic lead poisoning has a far better prognosis.

• ДЕТЕ ЈЕ ЉУБАВ У ВИДЉИВОМ ОБЛИКУ.Франсис Бејкон

енглески филозоф и државник(1561–1626)

• ПО ДЕТИЊСТВУ СЕ ЧОВЕК ПОЗНАЈЕ КАО ПО ЈУТРУ ДАН.Џон Милтон

енглески песник(1608–1674)

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